从 AngularJS 升级

Angular这个名字专指现在和未来的Angular版本，而AngularJS专指Angular的所有v1.x版本。

Angular is the name for the Angular of today and tomorrow. AngularJS is the name for all v1.x versions of Angular.

有很多大型AngularJS应用。 在决定迁移到Angular之前，首先要深入思考业务案例。 在这些案例中，最重要的部分之一是时间和需要付出的努力。 本章描述用于把AngularJS应用高效迁移到Angular平台的内置工具，每次讲一点点。

AngularJS apps are great. Always consider the business case before moving to Angular. An important part of that case is the time and effort to get there. This guide describes the built-in tools for efficiently migrating AngularJS projects over to the Angular platform, a piece at a time.

有些应用可能比其它的升级起来简单，还有一些方法能让把这项工作变得更简单。 即使在正式开始升级过程之前，我们可以准备AngularJS的程序，让它向Angular看齐。 这些准备步骤几乎都是关于如何让代码更加松耦合、更有可维护性，以及用现代开发工具提高速度的。 这意味着，这种准备工作不仅能让最终的升级变得更简单，而且还能提升AngularJS程序的质量。

Some applications will be easier to upgrade than others, and there are ways in which we can make it easier for ourselves. It is possible to prepare and align AngularJS applications with Angular even before beginning the upgrade process. These preparation steps are all about making the code more decoupled, more maintainable, and up to speed with modern development tools. That means the preparation work will not only make the eventual upgrade easier, but will also generally improve our AngularJS applications.

成功升级的关键之一是增量式的实现它，通过在同一个应用中一起运行这两个框架，并且逐个把AngularJS的组件迁移到Angular中。 这意味着可以在不必打断其它业务的前提下，升级更大、更复杂的应用程序，因为这项工作可以多人协作完成，在一段时间内逐渐铺开。 Angular upgrade模块的设计目标就是让你渐进、无缝的完成升级。

One of the keys to a successful upgrade is to do it incrementally, by running the two frameworks side by side in the same application, and porting AngularJS components to Angular one by one. This makes it possible to upgrade even large and complex applications without disrupting other business, because the work can be done collaboratively and spread over a period of time. The upgrade module in Angular has been designed to make incremental upgrading seamless.

1. 准备工作

   Preparation

   1. 遵循Angular风格指南

      Follow the Angular Style Guide

   2. 使用模块加载器

      Using a Module Loader

   3. 迁移到TypeScript

      Migrating to TypeScript

   4. 使用组件型指令

      Using Component Directives

2. 通过升级模块进行升级

   Upgrading with The Upgrade Module

   1. 升级模块是如何工作的

      How The Upgrade Module Works

   2. 引导混合(hybrid)应用

      Bootstrapping hybrid

   3. 从AngularJS的代码中使用Angular的组件

      Using Angular Components from AngularJS Code

   4. 从Angular的代码中使用AngularJS的组件

      Using AngularJS Component Directives from Angular Code

   5. 把AngularJS的内容投影(project)进Angular组件中

      Projecting AngularJS Content into Angular Components

   6. 把Angular的内容透传(transclude)到AngularJS的组件型指令中

      Transcluding Angular Content into AngularJS Component Directives

   7. 让AngularJS提供的依赖可以被注入到Angular

      Making AngularJS Dependencies Injectable to Angular

   8. 让Angular提供的依赖可以被注入到AngularJS

      Making Angular Dependencies Injectable to AngularJS

   9. 在混合式应用中使用预编译

      Using Ahead-of-time compilation with hybrid apps

   10. 在Angular和AngularJS之间进行路由

       Dividing routes between Angular and AngularJS

3. PhoneCat准备工作教程

   PhoneCat Upgrade Tutorial

   1. 切换到TypeScript

      Switching to TypeScript

   2. 安装Angular

      Installing Angular

   3. 引导混合版PhoneCat

      Bootstrapping a hybrid PhoneCat

   4. 升级Phone服务

      Upgrading the Phone service

   5. 升级组件

      Upgrading Components

   6. 对混合式应用进行AoT预编译

      AoT compile the hybrid app

   7. 添加Angular路由器并引导

      Adding The Angular Router And Bootstrap

   8. 和AngularJS说再见

      Say Goodbye to AngularJS

4. 附录：升级PhoneCat测试

   Appendix: Upgrading PhoneCat Tests

准备工作

Preparation

AngularJS应用程序的组织方式有很多种。当我们想把它们升级到Angular的时候， 有些做起来会比其它的更容易些。即使在我们开始升级之前，也有一些关键的技术和模式可以让我们将来升级时更轻松。

There are many ways to structure AngularJS applications. When we begin to upgrade these applications to Angular, some will turn out to be much more easy to work with than others. There are a few key techniques and patterns that we can apply to future proof our apps even before we begin the migration.

遵循Angular风格指南

Follow the Angular Style Guide

Angular风格指南收集了一些已证明能写出干净且可维护的AngularJS程序的模式与实践。 它包含了很多关于如何书写和组织Angular代码的有价值信息，同样重要的是，不应该采用的书写和组织Angular代码的方式。

The AngularJS Style Guide collects patterns and practices that have been proven to result in cleaner and more maintainable AngularJS applications. It contains a wealth of information about how to write and organize Angular code - and equally importantly - how not to write and organize Angular code.

Angular是一个基于AngularJS中最好的部分构思出来的版本。在这种意义上，它的目标和Angular风格指南是一样的： 保留AngularJS中好的部分，去掉坏的部分。当然，Angular还做了更多。 说这些的意思是：遵循这个风格指南可以让你写出更接近Angular程序的AngularJS程序。

Angular is a reimagined version of the best parts of AngularJS. In that sense, its goals are the same as the Angular Style Guide's: To preserve the good parts of AngularJS, and to avoid the bad parts. There's a lot more to Angular than just that of course, but this does mean that following the style guide helps make your AngularJS app more closely aligned with Angular.

有一些特别的规则可以让使用Angular的upgrade模块进行增量升级变得更简单：

There are a few rules in particular that will make it much easier to do an incremental upgrade using the Angular upgrade module:

• 单一规则 规定每个文件应该只放一个组件。这不仅让组件更容易浏览和查找，而且还将允许我们逐个迁移它们的语言和框架。 在这个范例程序中，每个控制器、工厂和过滤器都在它自己的源文件中。

  The Rule of 1 states that there should be one component per file. This not only makes components easy to navigate and find, but will also allow us to migrate them between languages and frameworks one at a time. In this example application, each controller, component, service, and filter is in its own source file.

• 按特性分目录的结构和模块化规则在较高的抽象层定义了一些相似的原则：应用程序中的不同部分应该被分到不同的目录和Angular模块中。

  The Folders-by-Feature Structure and Modularity rules define similar principles on a higher level of abstraction: Different parts of the application should reside in different directories and Angular modules.

如果应用程序能用这种方式把每个特性分到一个独立目录中，它也就能每次迁移一个特性。 对于那些还没有这么做的程序，强烈建议把应用这条规则作为准备步骤。而且这也不仅仅对升级有价值， 它还是一个通用的规则，可以让你的程序更“坚实”。

When an application is laid out feature per feature in this way, it can also be migrated one feature at a time. For applications that don't already look like this, applying the rules in the Angular style guide is a highly recommended preparation step. And this is not just for the sake of the upgrade - it is just solid advice in general!

使用模块加载器

Using a Module Loader

当我们把应用代码分解成每个文件中放一个组件之后，我们通常会得到一个由大量相对较小的文件组成的项目结构。 这比组织成少量大文件要整洁得多，但如果你不得不通过<script>标签在HTML页面中加载所有这些文件，那就不好玩了。 尤其是当你不得不按正确的顺序维护这些标签时更是如此。 这就是为什么开始使用模块加载器是一个好主意了。

When we break application code down into one component per file, we often end up with a project structure with a large number of relatively small files. This is a much neater way to organize things than a small number of large files, but it doesn't work that well if you have to load all those files to the HTML page with <script> tags. Especially when you also have to maintain those tags in the correct order. That's why it's a good idea to start using a module loader.

使用模块加载器，比如SystemJS、 Webpack或Browserify， 可以让我们在程序中使用TypeScript或ES2015语言内置的模块系统。 我们可以使用import和export特性来明确指定哪些代码应该以及将会被在程序的不同部分之间共享。 对于ES5程序来说，我们可以改用CommonJS风格的require和module.exports特性代替。 无是论哪种情况，模块加载器都会按正确的顺序加载程序中用到的所有代码。

Using a module loader such as SystemJS, Webpack, or Browserify allows us to use the built-in module systems of the TypeScript or ES2015 languages in our apps. We can use the import and export features that explicitly specify what code can and will be shared between different parts of the application. For ES5 applications we can use CommonJS style require and module.exports features. In both cases, the module loader will then take care of loading all the code the application needs in the correct order.

当我们的应用程序投入生产环境时，模块加载器也会让把所有这些文件打成完整的产品包变得更容易。

When we then take our applications into production, module loaders also make it easier to package them all up into production bundles with batteries included.

迁移到TypeScript

Migrating to TypeScript

Angular升级计划的一部分是引入TypeScript，即使在开始升级之前，引入TypeScript编译器也是有意义的。 这意味着等真正升级的时候需要学习和思考的东西更少。 它还意味着我们可以在AngularJS代码中开始使用TypeScript的特性。

If part of our Angular upgrade plan is to also take TypeScript into use, it makes sense to bring in the TypeScript compiler even before the upgrade itself begins. This means there's one less thing to learn and think about during the actual upgrade. It also means we can start using TypeScript features in our AngularJS code.

因为TypeScript是ECMAScript 2015的一个超集，而ES2015又是ECMAScript 5的一个超集。 这意味着除了安装一个TypeScript编译器，并把文件名都从*.js改成*.ts之外，其实什么都不用做。 当然，如果仅仅这样做也没什么大用，也没什么令人兴奋之处。 下面这些额外步骤可以让我们精神抖擞起来：

Since TypeScript is a superset of ECMAScript 2015, which in turn is a superset of ECMAScript 5, "switching" to TypeScript doesn't necessarily require anything more than installing the TypeScript compiler and switching renaming files from *.js to *.ts. But just doing that is not hugely useful or exciting, of course. Additional steps like the following can give us much more bang for the buck:

• 对那些使用了模块加载器的程序，TypeScript的导入和导出(这实际上是ECMAScript 2015导入和导出)可以把代码组织到模块中。

  For applications that use a module loader, TypeScript imports and exports (which are really ECMAScript 2015 imports and exports) can be used to organize code into modules.

• 类型注解可以逐步添加到已存在的函数和变量上，以固定它们的类型，并获得其优点：比如编译期错误检查、更好的支持自动完成，以及内联式文档等。

  Type annotations can be gradually added to existing functions and variables to pin down their types and get benefits like build-time error checking, great autocompletion support and inline documentation.

• 那些ES2015中新增的特性，比如箭头函数、let、const、默认函数参数、解构赋值等也能逐渐添加进来，让代码更有表现力。

  JavaScript features new to ES2015, like arrow functions, lets and consts, default function parameters, and destructuring assignments can also be gradually added to make the code more expressive.

• 服务和控制器可以转成类。这样我们就能一步步接近Angular的服务和组件类了，这样等到我们开始升级时，也会更简单。

  Services and controllers can be turned into classes. That way they'll be a step closer to becoming Angular service and component classes, which will make our life easier once we do the upgrade.

使用组件型指令

Using Component Directives

在Angular中，组件是用来构建用户界面的主要元素。我们把UI中的不同部分定义成组件，然后通过在模板中使用这些组件最终合成为UI。

In Angular, components are the main primitive from which user interfaces are built. We define the different parts of our UIs as components, and then compose the UI by using components in our templates.

我们在AngularJS中也能这么做。那就是一种定义了自己的模板、控制器和输入/输出绑定的指令 —— 跟Angular中对组件的定义是一样的。 要迁移到Angular，通过组件型指令构建的应用程序会比直接用ng-controller、ng-include和作用域继承等底层特性构建的要容易得多。

You can also do this in AngularJS, using component directives. These are directives that define their own templates, controllers, and input/output bindings - the same things that Angular components define. Applications built with component directives are much easier to migrate to Angular than applications built with lower-level features like ng-controller, ng-include, and scope inheritance.

要与Angular兼容，AngularJS的组件型指令应该配置下列属性：

To be Angular compatible, an AngularJS component directive should configure these attributes:

• restrict: 'E'。组件通常会以元素的方式使用。

  restrict: 'E'. Components are usually used as elements.

• scope: {} - 一个独立作用域。在Angular中，组件永远是从它们的环境中被隔离出来的，在AngularJS中，我们也应该这么做。

  scope: {} - an isolate scope. In Angular, components are always isolated from their surroundings, and we should do this in AngularJS too.

• bindToController: {}。组件的输入和输出应该绑定到控制器，而不是$scope。

  bindToController: {}. Component inputs and outputs should be bound to the controller instead of using the $scope.

• controller和controllerAs。组件有它们自己的控制器。

  controller and controllerAs. Components have their own controllers.

• template或templateUrl。组件有它们自己的模板。

  template or templateUrl. Components have their own templates.

组件型指令还可能使用下列属性：

Component directives may also use the following attributes:

• transclude: true：如果组件需要从其它地方透传内容，就设置它。

  transclude: true, if the component needs to transclude content from elsewhere.

• require：如果组件需要和父组件的控制器通讯，就设置它。

  require, if the component needs to communicate with some parent component's controller.

组件型指令不能使用下列属性：

Component directives may not use the following attributes:

• compile。它在Angular中将不再被支持。

  compile. This will not be supported in Angular.

• replace: true。Angular永远不会用组件模板替换一个组件元素。这个特性在AngularJS中也同样不建议使用了。

  replace: true. Angular never replaces a component element with the component template. This attribute is also deprecated in AngularJS.

• priority和terminal。虽然AngularJS的组件可能使用这些，但它们在Angular中已经没用了，并且最好不要再写依赖它们的代码。

  priority and terminal. While AngularJS components may use these, they are not used in Angular and it is better not to write code that relies on them.

AngularJS中一个完全向Angular架构对齐过的组件型指令是这样的：

An AngularJS component directive that is fully aligned with the Angular architecture may look something like this:

export function heroDetailDirective() {
  return {
    restrict: 'E',
    scope: {},
    bindToController: {
      hero: '=',
      deleted: '&'
    },
    template: `
      <h2>{{ctrl.hero.name}} details!</h2>
      <div><label>id: </label>{{ctrl.hero.id}}</div>
      <button ng-click="ctrl.onDelete()">Delete</button>
    `,
    controller: function() {
      this.onDelete = () => {
        this.deleted({hero: this.hero});
      };
    },
    controllerAs: 'ctrl'
  };
}

AngularJS.5引入了组件API，它让像这样定义指令变得更简单了。 为组件型指令使用这个API是一个好主意，因为：

AngularJS 1.5 introduces the component API that makes it easier to define directives like these. It is a good idea to use this API for component directives for several reasons:

• 它需要更少的样板代码。

  It requires less boilerplate code.

• 它强制使用组件的最佳实践，比如controllerAs。

  It enforces the use of component best practices like controllerAs.

• 对于指令中像scope和restrict这样的属性，它有良好的默认值。

  It has good default values for directive attributes like scope and restrict.

如果使用这个组件API进行快捷定义，那么上面看到的组件型指令就变成了这样：

The component directive example from above looks like this when expressed using the component API:

export const heroDetail = {
  bindings: {
    hero: '<',
    deleted: '&'
  },
  template: `
    <h2>{{$ctrl.hero.name}} details!</h2>
    <div><label>id: </label>{{$ctrl.hero.id}}</div>
    <button ng-click="$ctrl.onDelete()">Delete</button>
  `,
  controller: function() {
    this.onDelete = () => {
      this.deleted(this.hero);
    };
  }
};
import { Directive, ElementRef, Injector, Input, Output, EventEmitter } from '@angular/core';
import { UpgradeComponent } from '@angular/upgrade/static';
import { Hero } from '../hero';
@Directive({
  selector: 'hero-detail'
})
export class HeroDetailDirective extends UpgradeComponent {
  @Input() hero: Hero;
  @Output() deleted: EventEmitter<Hero>;
  constructor(elementRef: ElementRef, injector: Injector) {
    super('heroDetail', elementRef, injector);
  }
}

控制器的生命周期钩子$onInit()、$onDestroy()和$onChanges()是AngularJS.5引入的另一些便利特性。 它们都很接近于Angular中的等价物，所以，围绕它们组织组件生命周期的逻辑会更容易升级。

Controller lifecycle hook methods $onInit(), $onDestroy(), and $onChanges() are another convenient feature that AngularJS 1.5 introduces. They all have nearly exact equivalents in Angular, so organizing component lifecycle logic around them will ease the eventual Angular upgrade process.

使用升级适配器进行升级

Upgrading with The Upgrade Module

不管要升级什么，Angular中的upgrade模块都会是一个非常有用的工具 —— 除非是小到没功能的应用。 借助它，我们可以在同一个应用程序中混用并匹配AngularJS和2的组件，并让它们实现无缝的互操作。 这意味着我们不用必须一次性做完所有升级工作，因为在整个演进过程中，这两个框架可以很自然的和睦相处。

The upgrade module in Angular is a very useful tool for upgrading anything but the smallest of applications. With it we can mix and match AngularJS and Angular components in the same application and have them interoperate seamlessly. That means we don't have to do the upgrade work all at once, since there's a natural coexistence between the two frameworks during the transition period.

升级模块如何工作

How The Upgrade Module Works

upgrade模块提供的主要工具叫做UpgradeModule。这是一个服务，它可以引导并管理同时支持Angular和AngularJS的混合式应用程序。

The primary tool provided by the upgrade module is called the UpgradeModule. This is a service that can bootstrap and manage hybrid applications that support both Angular and AngularJS code.

当使用UpgradeModule时，我们实际做的是同时运行两个版本的Angular。所有Angular的代码运行在Angular框架中， 而AngularJS的代码运行在AngularJS框架中。所有这些都是真实的、全功能的框架版本。 没有进行任何仿真，所以我们可以期待同时存在这两个框架的所有特性和天生的行为。

When we use UpgradeModule, what we're really doing is running both versions of Angular at the same time. All Angular code is running in the Angular framework, and AngularJS code in the AngularJS framework. Both of these are the actual, fully featured versions of the frameworks. There is no emulation going on, so we can expect to have all the features and natural behavior of both frameworks.

所有这些事情的背后，本质上是一个框架中管理的组件和服务能和来自另一个中的进行互操作。 这发生在三个主要的领域：依赖注入、DOM和变更检测。

What happens on top of this is that components and services managed by one framework can interoperate with those from the other framework. This happens in three main areas: Dependency injection, the DOM, and change detection.

依赖注入

Dependency Injection

无论是在AngularJS中还是在Angular中，依赖注入都处于前沿和中心的位置，但在两个框架的工作原理上，却存在着一些关键的不同之处。

Dependency injection is front and center in both AngularJS and Angular, but there are some key differences between the two frameworks in how it actually works.

就算有这么多不同点，也并不妨碍我们在依赖注入时进行互操作。UpgradeModule解决了这些差异，并让它们无缝的对接：

Even accounting for these differences we can still have dependency injection interoperability. The UpgradeModule resolves the differences and makes everything work seamlessly:

• 通过升级它们，我们就能让那些在AngularJS中能被注入的服务在Angular的代码中可用。 在框架之间共享的是服务的同一个单例对象。在Angular中，这些外来服务总是被放在根注入器中，并可用于所有组件。 它们总是具有字符串令牌 —— 跟它们在AngularJS中的令牌相同。

  You can make AngularJS services available for injection to Angular code by upgrading them. The same singleton instance of each service is shared between the frameworks. In Angular these services will always be in the root injector and available to all components.

• 通过降级它们，我们也能让那些在Angular中能被注入的服务在AngularJS的代码中可用。 只有那些来自Angular根注入器的服务才能被降级。同样的，在框架之间共享的是同一个单例对象。 当我们注册一个要降级的服务时，要明确指定一个打算在AngularJS中使用的字符串令牌。

  You can also make Angular services available for injection to AngularJS code by downgrading them. Only services from the Angular root injector can be downgraded. Again, the same singleton instances are shared between the frameworks. When we register a downgrade, we explicitly specify a string token that we want to use in AngularJS.

组件与DOM

Components and the DOM

在混合式应用中，我们能同时发现那些来自AngularJS和Angular中组件和指令的DOM。 这些组件通过它们各自框架中的输入和输出绑定来互相通讯，它们由UpgradeModule桥接在一起。 它们也能通过共享被注入的依赖彼此通讯，就像前面所说的那样。

What we'll find in the DOM of a hybrid application are components and directives from both AngularJS and Angular. These components communicate with each other by using the input and output bindings of their respective frameworks, which the UpgradeModule bridges together. They may also communicate through shared injected dependencies, as described above.

要弄明白在一个混合式应用的DOM中发生了什么，有两点很关键：

There are two key things to understand about what happens in the DOM of a hybrid application:

1. DOM中的每个元素都只能被两个框架之一拥有。另一个框架会忽略它。 如果一个元素被AngularJS拥有，Angular就会当它不存在。反之亦然。

   Every element in the DOM is owned by exactly one of the two frameworks. The other framework ignores it. If an element is owned by AngularJS, Angular treats it as if it didn't exist, and vice versa.

2. 应用的根节点总是来自AngularJS中的模板。

   The root of the application is always an AngularJS template.

所以，混合式应用总是像AngularJS程序那样启动，处理根模板的也是AngularJS. 然后，当这个应用的模板中使用到了Angular的组件时，Angular才开始参与。 这个组件的视图由Angular进行管理，而且它还可以使用一系列的Angular组件和指令。

So a hybrid application begins life as an AngularJS application, and it is AngularJS that processes its root template. Angular then steps into the picture when an Angular component is used somewhere in the application templates. That component's view will then be managed by Angular, and it may use any number of Angular components and directives.

更进一步说，我们可以按照需要，任意穿插使用这两个框架。 使用下面的两种方式之一，我们可以自由穿梭于这两个框架的边界：

Beyond that, we may interleave the two frameworks as much as we need to. We always cross the boundary between the two frameworks by one of two ways:

1. 通过使用来自另一个框架的组件：AngularJS的模板中用到了Angular的组件，或者Angular的模板中使用了AngularJS的组件。

   By using a component from the other framework: An AngularJS template using an Angular component, or an Angular template using an AngularJS component.

2. 通过透传(transclude)或投影(project)来自另一个框架的内容。UpgradeModule牵线搭桥，把AngularJS的透传概念和Angular的内容投影概念关联起来。

   By transcluding or projecting content from the other framework. The UpgradeModule bridges the related concepts of AngularJS transclusion and Angular content projection together.

当我们使用一个属于另一个框架的组件时，就会发生一个跨框架边界的切换。不过，这种切换只发生在该组件元素的子节点上。 考虑一个场景，我们从AngularJS中使用一个Angular组件，就像这样：

Whenever we use a component that belongs to the other framework, a switch between framework boundaries occurs. However, that switch only happens to the children of the component element. Consider a situation where we use an Angular component from AngularJS like this:

<a-component></a-component>

此时，<a-component>这个DOM元素仍然由AngularJS管理，因为它是在AngularJS的模板中定义的。 这也意味着你可以往它上面添加别的AngularJS指令，却不能添加Angular的指令。 只有在<a-component>组件的模板中才是Angular的天下。同样的规则也适用于在Angular中使用AngularJS组件型指令的情况。

The DOM element <a-component> will remain to be an AngularJS managed element, because it's defined in an AngularJS template. That also means you can apply additional AngularJS directives to it, but not Angular directives. It is only in the template of the <a-component> where Angular steps in. This same rule also applies when you use AngularJS component directives from Angular.

变更检测

Change Detection

AngularJS中的变更检测全是关于scope.$apply()的。在每个事件发生之后，scope.$apply()就会被调用。 这或者由框架自动调用，或者在某些情况下由我们自己的代码手动调用。它是发生变更检测以及更新数据绑定的时间点。

Change detection in AngularJS is all about scope.$apply(). After every event that occurs, scope.$apply() gets called. This is done either automatically by the framework, or in some cases manually by our own code. It is the point in time when change detection occurs and data bindings get updated.

在Angular中，事情有点不一样。虽然变更检测仍然会在每一个事件之后发生，却不再需要每次调用scope.$apply()了。 这是因为所有Angular代码都运行在一个叫做Angular zone的地方。 Angular总是知道什么时候代码执行完了，也就知道了它什么时候应该触发变更检测。代码本身并不需要调用scope.$apply()或其它类似的东西。

In Angular things are different. While change detection still occurs after every event, no one needs to call scope.$apply() for that to happen. This is because all Angular code runs inside something called the Angular zone. Angular always knows when the code finishes, so it also knows when it should kick off change detection. The code itself doesn't have to call scope.$apply() or anything like it.

在这种混合式应用的案例中，UpgradeModule在AngularJS的方法和Angular的方法之间建立了桥梁。发生了什么呢？

In the case of hybrid applications, the UpgradeModule bridges the AngularJS and Angular approaches. Here's what happens:

• 应用中发生的每件事都运行在Angular的zone里。 无论事件发生在AngularJS还是Angular的代码中，都是如此。

  Everything that happens in the application runs inside the Angular zone. This is true whether the event originated in AngularJS or Angular code. The zone triggers Angular change detection after every event.

• UpgradeModule将在每一次离开Angular zone时调用AngularJS的$rootScope.$apply()。这样也就同样会在每个事件之后触发AngularJS的变更检测。

  The UpgradeModule will invoke the AngularJS $rootScope.$apply() after every turn of the Angular zone. This also triggers AngularJS change detection after every event.

在实践中，这意味着我们不用在自己的代码中调用$apply()，而不用管这段代码是在AngularJS还是Angular中。 UpgradeModule都替我们做了。我们仍然可以调用$apply()，也就是说我们不必从现有代码中移除此调用。 但是在混合式应用中，那些调用没有任何效果。

What this means in practice is that we do not need to call $apply() in our code, regardless of whether it is in AngularJS on Angular. The UpgradeModule does it for us. We can still call $apply() so there is no need to remove such calls from existing code. Those calls just don't have any effect in a hybrid application.

当我们降级一个Angular组件，然后把它用于AngularJS中时，组件的输入属性就会被AngularJS的变更检测体系监视起来。 当那些输入属性发生变化时，组件中相应的属性就会被设置。我们也能通过实现OnChanges 接口来挂钩到这些更改，就像它未被降级时一样。

When we downgrade an Angular component and then use it from AngularJS, the component's inputs will be watched using AngularJS change detection. When those inputs change, the corresponding properties in the component are set. We can also hook into the changes by implementing the OnChanges interface in the component, just like we could if it hadn't been downgraded.

相应的，当我们把AngularJS的组件升级给Angular使用时，在这个组件型指令的scope(或bindToController)中定义的所有绑定， 都将被挂钩到Angular的变更检测体系中。它们将和标准的Angular输入属性被同等对待，并当它们发生变化时设置回scope(或控制器)上。

Correspondingly, when we upgrade an AngularJS component and use it from Angular, all the bindings defined for the component directive's scope (or bindToController) will be hooked into Angular change detection. They will be treated as regular Angular inputs and set onto the scope (or controller) when they change.

通过Angular的NgModule来使用UpgradeModule

Using UpgradeModule with Angular NgModules

AngularJS还是Angular都有自己的模块概念，来帮你我们把应用组织成一些紧密相关的功能块。

Both AngularJS and Angular have their own concept of modules to help organize an application into cohesive blocks of functionality.

它们在架构和实现的细节上有着显著的不同。 在AngularJS中，我们会把AngularJS的资源添加到angular.module属性上。 在Angular中，我们会创建一个或多个带有NgModule装饰器的类，这些装饰器用来在元数据中描述Angular资源。差异主要来自这里。

Their details are quite different in architecture and implementation. In AngularJS, you add Angular assets to the angular.module property. In Angular, you create one or more classes adorned with an NgModule decorator that describes Angular assets in metadata. The differences blossom from there.

在混合式应用中，我们同时运行了两个版本的Angular。 这意味着我们至少需要AngularJS和Angular各提供一个模块。 当我们使用AngularJS的模块进行引导时，就得把Anuglar 2的模块传给UpgradeModule。我们来看看怎么做。

In a hybrid application we run both versions of Angular at the same time. That means that we need at least one module each from both AngularJS and Angular . We will import UpgradeModule inside our Angular module, and then use it for bootstrapping our AngularJS module. Let's see how.

引导AngularJS+2的混合式应用程序

Bootstrapping hybrid applications

使用UpgradeModule升级应用的第一步总是把它引导成一个同时支持AngularJS和Angular的混合式应用。

The first step to upgrading an application using the UpgradeModule is always to bootstrap it as a hybrid that supports both AngularJS and Angular, but still is an AngularJS app at top level.

纯粹的AngularJS应用可以用两种方式引导：在HTML页面中的某处使用ng-app指令，或者从JavaScript中调用 angular.bootstrap。 在Angular中，只有第二种方法是可行的，因为它没有ng-app指令。在混合式应用中也同样只能用第二种方法。 所以，在将AngularJS应用切换到混合模式之前，把它改为用JavaScript引导的方式是一个不错的起点。

Pure AngularJS applications can be bootstrapped in two ways: By using an ng-app directive somewhere on the HTML page, or by calling angular.bootstrap from JavaScript. In Angular, only the second method is possible - there is no ng-app in Angular. This is also the case for hybrid applications. Therefore, it is a good preliminary step to switch AngularJS applications to use the JavaScript bootstrap method even before switching them to hybrid mode.

比如说我们有个由ng-app驱动的引导过程，就像这个：

Say we have an ng-app driven bootstrap such as this one:

<!DOCTYPE HTML>
<html>
  <head>
    <base href="/">
    <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.5.3/angular.js"></script>
    <script src="app/ajs-ng-app/app.module.js"></script>
  </head>
  <body ng-app="heroApp" ng-strict-di>
    <div id="message" ng-controller="MainCtrl as mainCtrl">
      {{ mainCtrl.message }}
    </div>
  </body>
</html>

我们可以从HTML中移除ng-app和ng-strict-di指令，改为从JavaScript中调用angular.bootstrap，它能达到同样效果：

We can remove the ng-app and ng-strict-di directives from the HTML and instead switch to calling angular.bootstrap from JavaScript, which will result in the same thing:

angular.bootstrap(document.body, ['heroApp'], {strictDi: true});

现在，把Angular引入项目中。根据搭建本地开发环境中的指导，你可以有选择的从“快速起步”的Github仓库中拷贝素材进来。

Now introduce Angular to the project. Inspired by instructions in the Setup, you can selectively copy in material from the QuickStart github repository.

接下来，创建一个app.module.ts文件，并添加下列NgModule类：

Next, create an app.module.ts file and add the following NgModule class:

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { UpgradeModule } from '@angular/upgrade/static';
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule
  ]
})
export class AppModule {
  ngDoBootstrap() {}
}

这个最小化的NgModule导入了BrowserModule，该模块是每个基于浏览器的Angular应用都必须具备的。

This bare minimum NgModule imports BrowserModule, the module every Angular browser-based app must have.

它还从@angular/upgrade/static导入了UpgradeModule，并添加了一个ngDoBootstrap空的覆盖方法，防止 Angular启动它自身。

It also imports UpgradeModule from @angular/upgrade/static, and adds an override to prevent Angular from bootstrapping itself in the form of the ngDoBootstrap empty class method.

现在我们使用platformBrowserDynamic的bootstrapModule方法启动AppModule。 接着我们使用依赖注入来获取AppModule中的一个UpgradeModule实例， 并使用它来启动我们的AngularJS应用。 upgrade.bootstrap方法接受与angular.bootstrap相同的参数。

Now we bootstrap AppModule using platformBrowserDynamic's bootstrapModule method. Then we use dependency injection to get a hold of the UpgradeModule instance in AppModule, and use it to bootstrap our AngularJS app. The upgrade.bootstrap method takes the exact same arguments as angular.bootstrap:

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
platformBrowserDynamic().bootstrapModule(AppModule).then(platformRef => {
  const upgrade = platformRef.injector.get(UpgradeModule) as UpgradeModule;
  upgrade.bootstrap(document.body, ['heroApp'], {strictDi: true});
});

我们还需要通过npm install @angular/upgrade --save命令安装@angular/upgrade包，并且为@angular/upgrade/static包添加一个映射关系：

We also need to install the @angular/upgrade package via npm install @angular/upgrade --save and add a mapping for the @angular/upgrade/static package:

'@angular/upgrade/static': 'npm:@angular/upgrade/bundles/upgrade-static.umd.js',

恭喜！我们就要开始运行AngularJS+2的混合式应用程序了！所有现存的AngularJS代码会像以前一样正常工作，但是我们现在也同样可以运行Angular代码了。

Congratulations! You're running a hybrid application! The existing AngularJS code works as before and you're ready to run Angular code.

在AngularJS的代码中使用Angular的组件

Using Angular Components from AngularJS Code

一旦我们开始运行混合式应用，我们就可以开始逐渐升级代码了。做这件事的一种更常见的模式就是在AngularJS的上下文中使用Angular的组件。 该组件可能是全新的，也可能是把原本AngularJS的组件用Angular重写而成的。

Once we're running a hybrid app, we can start the gradual process of upgrading code. One of the more common patterns for doing that is to use an Angular component in an AngularJS context. This could be a completely new component or one that was previously AngularJS but has been rewritten for Angular.

假设我们有一个简单的用来显示英雄信息的Angular组件：

Say we have a simple Angular component that shows information about a hero:

import { Component } from '@angular/core';
@Component({
  selector: 'hero-detail',
  template: `
    <h2>Windstorm details!</h2>
    <div><label>id: </label>1</div>
  `
})
export class HeroDetailComponent { }

如果我们想在AngularJS中使用这个组件，我们就得用downgradeComponent()方法把它降级。 如果我们这么做，就会得到一个AngularJS的指令，我们可以把它注册到AngularJS的模块中：

If we want to use this component from AngularJS, we need to downgrade it using the downgradeComponent() method. What we get when we do that is an AngularJS directive, which we can then register into our AngularJS module:

import { HeroDetailComponent } from './hero-detail.component';
/* . . . */
import { downgradeComponent } from '@angular/upgrade/static';
angular.module('heroApp', [])
  .directive(
    'heroDetail',
    downgradeComponent({component: HeroDetailComponent}) as angular.IDirectiveFactory
  );

由于HeroDetailComponent是一个Angular组件，所以我们必须同时把它加入AppModule的declarations字段中。

Because HeroDetailComponent is an Angular component, we must also add it to the declarations in the AppModule.

并且由于这个组件在AngularJS模块中使用，也是我们Angular应用的一个入口点，我们还需要 将它加入到Angular模块的entryComponents列表中。

And because this component is being used from the AngularJS module, and is an entry point into our Angular application, we also need to add it to the entryComponents for our Angular module.

import { HeroDetailComponent } from './hero-detail.component';
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule
  ],
  declarations: [
    HeroDetailComponent
  ],
  entryComponents: [
    HeroDetailComponent
  ]
})
export class AppModule {
  ngDoBootstrap() {}
}

这里我们得到的是一个叫做heroDetail的AngularJS指令，我们可以像用其它指令一样把它用在AngularJS模板中。

The net result is an AngularJS directive called heroDetail, that we can use like any other directive in our AngularJS templates.

<hero-detail></hero-detail>

当然，大多数组件都不像这个这么简单。它们中很多都有输入属性和输出属性，来把它们连接到外部世界。 Angular的英雄详情组件带有像这样的输入属性与输出属性：

Most components are not quite this simple, of course. Many of them have inputs and outputs that connect them to the outside world. An Angular hero detail component with inputs and outputs might look like this:

import { Component, EventEmitter, Input, Output } from '@angular/core';
import { Hero } from '../hero';
@Component({
  selector: 'hero-detail',
  template: `
    <h2>{{hero.name}} details!</h2>
    <div><label>id: </label>{{hero.id}}</div>
    <button (click)="onDelete()">Delete</button>
  `
})
export class HeroDetailComponent {
  @Input() hero: Hero;
  @Output() deleted = new EventEmitter<Hero>();
  onDelete() {
    this.deleted.emit(this.hero);
  }
}

这些输入属性和输出属性的值来自于AngularJS的模板，而downgradeComponent()方法负责桥接它们：

These inputs and outputs can be supplied from the AngularJS template, and the downgradeComponent() method takes care of bridging them overvia the inputs and outputs arrays:

import { HeroDetailComponent } from './hero-detail.component';
/* . . . */
angular.module('heroApp', [])
  .controller('MainController', MainController)
  .directive('heroDetail', downgradeComponent({
    component: HeroDetailComponent,
    inputs: ['hero'],
    outputs: ['deleted']
  }) as angular.IDirectiveFactory);

<div ng-controller="MainController as mainCtrl">
  <hero-detail [hero]="mainCtrl.hero"
               (deleted)="mainCtrl.onDelete($event)">
  </hero-detail>
</div>

注意，虽然我们正在AngularJS的模板中，但却在使用Angular的属性(Attribute)语法来绑定到输入属性与输出属性。 这是降级的组件本身要求的。而表达式本身仍然是标准的AngularJS表达式。

Note that even though we are in an AngularJS template, we're using Angular attribute syntax to bind the inputs and outputs. This is a requirement for downgraded components. The expressions themselves are still regular AngularJS expressions.

[myHero]="hero"

[my-hero]="hero"

$event变量能被用在输出属性里，以访问这个事件所发出的对象。这个案例中它是Hero对象，因为this.deleted.emit()函数曾把它传了出来。

The $event variable can be used in outputs to gain access to the object that was emitted. In this case it will be the Hero object, because that is what was passed to this.deleted.emit().

由于这是一个AngularJS模板，虽然它已经有了Angular中绑定的属性(Attribute)，我们仍可以在这个元素上使用其它AngularJS指令。 例如，我们可以用ng-repeat简单的制作该组件的多份拷贝：

Since this is an AngularJS template, we can still use other AngularJS directives on the element, even though it has Angular binding attributes on it. For example, we can easily make multiple copies of the component using ng-repeat:

<div ng-controller="MainController as mainCtrl">
  <hero-detail [hero]="hero"
               (deleted)="mainCtrl.onDelete($event)"
               ng-repeat="hero in mainCtrl.heroes">
  </hero-detail>
</div>

从Angular代码中使用AngularJS组件型指令

Using AngularJS Component Directives from Angular Code

现在，我们已经能在Angular中写一个组件，并把它用于AngularJS代码中了。 当我们从低级组件开始移植，并往上走时，这非常有用。但在另外一些情况下，从相反的方向进行移植会更加方便： 从高级组件开始，然后往下走。这也同样能用UpgradeModule完成。 我们可以升级AngularJS组件型指令，然后从Angular中用它们。

So, we can write an Angular component and then use it from AngularJS code. This is very useful when we start our migration from lower-level components and work our way up. But in some cases it is more convenient to do things in the opposite order: To start with higher-level components and work our way down. This too can be done using the UpgradeModule. We can upgrade AngularJS component directives and then use them from Angular.

不是所有种类的AngularJS指令都能升级。该指令必须是一个严格的组件型指令，具有上面的准备指南中描述的那些特征。 确保兼容性的最安全的方式是AngularJS.5中引入的组件API。

Not all kinds of AngularJS directives can be upgraded. The directive really has to be a component directive, with the characteristics described in the preparation guide above. Our safest bet for ensuring compatibility is using the component API introduced in AngularJS 1.5.

可升级组件的简单例子是只有一个模板和一个控制器的指令：

A simple example of an upgradable component is one that just has a template and a controller:

export const heroDetail = {
  template: `
    <h2>Windstorm details!</h2>
    <div><label>id: </label>1</div>
  `,
  controller: function() {
  }
};

我们可以使用UpgradeComponent方法来把这个组件升级到Angular。 具体方法是创建一个Angular指令，继承UpgradeComponent，在其构造函数中进行super调用， 这样我们就得到一个完全升级的AngularJS组件，并且可以Angular中使用。 剩下是工作就是把它加入到AppModule的declarations数组。

We can upgrade this component to Angular using the UpgradeComponent class. By creating a new Angular directive that extends UpgradeComponent and doing a super call inside it's constructor, we have a fully upgrade AngularJS component to be used inside Angular . All that is left is to add it to AppModule's declarations array.

import { Directive, ElementRef, Injector } from '@angular/core';
import { UpgradeComponent } from '@angular/upgrade/static';
@Directive({
  selector: 'hero-detail'
})
export class HeroDetailDirective extends UpgradeComponent {
  constructor(elementRef: ElementRef, injector: Injector) {
    super('heroDetail', elementRef, injector);
  }
}

@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule
  ],
  declarations: [
    HeroDetailDirective,
    /* . . . */
  ]
})
export class AppModule {
  ngDoBootstrap() {}
}

升级后的组件也可能有输入属性和输出属性，它们是在原AngularJS组件型指令的scope/controller绑定中定义的。 当我们从Angular模板中使用该组件时，我们要使用Angular模板语法来提供这些输入属性和输出属性，但要遵循下列规则：

An upgraded component may also have inputs and outputs, as defined by the scope/controller bindings of the original AngularJS component directive. When we use the component from an Angular template, we provide the inputs and outputs using Angular template syntax, with the following rules:

举个例子，假设我们在AngularJS中有一个表示“英雄详情”的组件型指令，它带有一个输入属性和一个输出属性：

As an example, say we have a hero detail AngularJS component directive with one input and one output:

export const heroDetail = {
  bindings: {
    hero: '<',
    deleted: '&'
  },
  template: `
    <h2>{{$ctrl.hero.name}} details!</h2>
    <div><label>id: </label>{{$ctrl.hero.id}}</div>
    <button ng-click="$ctrl.onDelete()">Delete</button>
  `,
  controller: function() {
    this.onDelete = () => {
      this.deleted(this.hero);
    };
  }
};

我们可以把这个组件升级到Angular，然后使用Angular的模板语法提供这个输入属性和输出属性：

We can upgrade this component to Angular, annotate inputs and outputs in the upgrade directive,and then provide the input and output using Angular template syntax:

import { Directive, ElementRef, Injector, Input, Output, EventEmitter } from '@angular/core';
import { UpgradeComponent } from '@angular/upgrade/static';
import { Hero } from '../hero';
@Directive({
  selector: 'hero-detail'
})
export class HeroDetailDirective extends UpgradeComponent {
  @Input() hero: Hero;
  @Output() deleted: EventEmitter<Hero>;
  constructor(elementRef: ElementRef, injector: Injector) {
    super('heroDetail', elementRef, injector);
  }
}

import { Component } from '@angular/core';
import { Hero } from '../hero';
@Component({
  selector: 'my-container',
  template: `
    <h1>Tour of Heroes</h1>
    <hero-detail [hero]="hero"
                 (deleted)="heroDeleted($event)">
    </hero-detail>
  `
})
export class ContainerComponent {
  hero = new Hero(1, 'Windstorm');
  heroDeleted(hero: Hero) {
    hero.name = 'Ex-' + hero.name;
  }
}

把AngularJS的内容投影到Angular组件中

Projecting AngularJS Content into Angular Components

如果我们在AngularJS模板中使用降级后的Angular组件时，可能会需要把模板中的一些内容投影进那个组件。 这也是可能的，虽然在Angular中并没有透传(transclude)这样的东西，但它有一个非常相似的概念，叫做内容投影。 UpgradeModule也能让这两个特性实现互操作。

When we are using a downgraded Angular component from an AngularJS template, the need may arise to transclude some content into it. This is also possible. While there is no such thing as transclusion in Angular, there is a very similar concept called content projection. The UpgradeModule is able to make these two features interoperate.

Angular的组件通过使用<ng-content>标签来支持内容投影。下面是这类组件的一个例子：

Angular components that support content projection make use of an <ng-content> tag within them. Here's an example of such a component:

import { Component, Input } from '@angular/core';
import { Hero } from '../hero';
@Component({
  selector: 'hero-detail',
  template: `
    <h2>{{hero.name}}</h2>
    <div>
      <ng-content></ng-content>
    </div>
  `
})
export class HeroDetailComponent {
  @Input() hero: Hero;
}

当从AngularJS中使用该组件时，我们可以为它提供内容。正如它们将在AngularJS中被透传一样， 它们也在Angular中被投影到了<ng-content>标签所在的位置：

When using the component from AngularJS, we can supply contents for it. Just like they would be transcluded in AngularJS, they get projected to the location of the <ng-content> tag in Angular:

<div ng-controller="MainController as mainCtrl">
  <hero-detail [hero]="mainCtrl.hero">
    <!-- Everything here will get projected -->
    <p>{{mainCtrl.hero.description}}</p>
  </hero-detail>
</div>

把Angular的内容透传进AngularJS的组件型指令

Transcluding Angular Content into AngularJS Component Directives

就像我们能把AngularJS的内容投影进Angular组件一样，我们也能把Angular的内容透传进AngularJS的组件， 但不管怎样，我们都要使用它们升级过的版本。

Just like we can project AngularJS content into Angular components, we can transclude Angular content into AngularJS components, whenever we are using upgraded versions from them.

如果一个AngularJS组件型指令支持透传，它就会在自己的模板中使用ng-transclude指令标记出透传到的位置：

When an AngularJS component directive supports transclusion, it may use the ng-transclude directive in its template to mark the transclusion point:

export const heroDetail = {
  bindings: {
    hero: '='
  },
  template: `
    <h2>{{$ctrl.hero.name}}</h2>
    <div>
      <ng-transclude></ng-transclude>
    </div>
  `
};

如果我们升级这个组件，并把它用在Angular中，我们就能把准备透传的内容放进这个组件的标签中。

If we upgrade this component and use it from Angular, we can populate the component tag with contents that will then get transcluded:

import { Component } from '@angular/core';
import { Hero } from '../hero';
@Component({
  selector: 'my-container',
  template: `
    <hero-detail [hero]="hero">
      <!-- Everything here will get transcluded -->
      <p>{{hero.description}}</p>
    </hero-detail>
  `
})
export class ContainerComponent {
  hero = new Hero(1, 'Windstorm', 'Specific powers of controlling winds');
}

让AngularJS中的依赖可被注入到Angular

Making AngularJS Dependencies Injectable to Angular

当运行一个混合式应用时，我们可能会遇到这种情况：我们需要把某些AngularJS的依赖注入到Angular代码中。 这可能是因为某些业务逻辑仍然在AngularJS服务中，或者需要某些AngularJS的内置服务，比如$location或$timeout。

When running a hybrid app, we may bump into situations where we need to have some AngularJS dependencies to be injected to Angular code. This may be because we have some business logic still in AngularJS services, or because we need some of AngularJS's built-in services like $location or $timeout.

在这些情况下，把一个AngularJS提供商升级到Angular也是有可能的。这就让它将来有可能被注入到Angular代码中的某些地方。 比如，我们可能在AngularJS中有一个名叫HeroesService的服务：

In these situations, it is possible to upgrade an AngularJS provider to Angular. This makes it possible to then inject it somewhere in Angular code. For example, we might have a service called HeroesService in AngularJS:

import { Hero } from '../hero';
export class HeroesService {
  get() {
    return [
      new Hero(1, 'Windstorm'),
      new Hero(2, 'Spiderman')
    ];
  }
}

我们可以Angular的工厂提供商（factory provider）升级该服务， 它从AngularJS的$injector请求服务。Angular依赖的名称由你确定：

We can upgrade the service using a Angular Factory provider that requests the service from the AngularJS $injector.

我们建议在一个独立的ajs-upgraded-providers.ts中声明这个工厂提供商，以便把它们都放在一起，这样便于引用、创建新的以及在升级完毕时删除它们。

We recommend declaring the Factory Provider in a separate ajs-upgraded-providers.ts file so that they are all together, making it easier to reference them, create new ones and delete them once the upgrade is over.

我们还建议导出heroesServiceFactory函数，以便AOT编译器可以拿到它们。

It's also recommended to export the heroesServiceFactory function so that Ahead-of-Time compilation can pick it up.

import { HeroesService } from './heroes.service';
export function heroesServiceFactory(i: any) {
  return i.get('heroes');
}
export const heroesServiceProvider = {
  provide: HeroesService,
  useFactory: heroesServiceFactory,
  deps: ['$injector']
};

import { heroesServiceProvider } from './ajs-upgraded-providers';
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule
  ],
  providers: [
    heroesServiceProvider
  ],
  /* . . . */
})
export class AppModule {
  ngDoBootstrap() {}
}

然后我们可以一个字符串型令牌，把它注入到Angular中：

We can then inject it in Angular using it's class as a type annotation:

import { Component } from '@angular/core';
import { HeroesService } from './heroes.service';
import { Hero } from '../hero';
@Component({
  selector: 'hero-detail',
  template: `
    <h2>{{hero.id}}: {{hero.name}}</h2>
  `
})
export class HeroDetailComponent {
  hero: Hero;
  constructor(heroes: HeroesService) {
    this.hero = heroes.get()[0];
  }
}

让Angular的依赖能被注入到AngularJS中

Making Angular Dependencies Injectable to AngularJS

除了能升级AngularJS依赖之外，我们还能降级Angular的依赖，以便我们能在AngularJS中使用它们。 当我们已经开始把服务移植到Angular或在Angular中创建新服务，但同时还有一些用AngularJS写成的组件时，这会非常有用。

In addition to upgrading AngularJS dependencies, we can also downgrade Angular dependencies, so that we can use them from AngularJS. This can be useful when we start migrating services to Angular or creating new services in Angular while we still have components written in AngularJS.

例如，我们可能有一个Angular的Heroes服务：

For example, we might have an Angular service called Heroes:

import { Injectable } from '@angular/core';
import { Hero } from '../hero';
@Injectable()
export class Heroes {
  get() {
    return [
      new Hero(1, 'Windstorm'),
      new Hero(2, 'Spiderman')
    ];
  }
}

仿照Angular组件，我们通过把该提供商加入NgModule的providers列表中来注册它。

Again, as with Angular components, register the provider with the NgModule by adding it to the module's providers list.

import { Heroes } from './heroes';
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule
  ],
  providers: [ Heroes ]
})
export class AppModule {
  ngDoBootstrap() {}
}

现在，我们使用upgradeAdapter.downgradeNg2Provider()来把Angular的Heroes包装成AngularJS的工厂函数，并把这个工厂注册进AngularJS的模块中。 依赖在AngularJS中的名字你可以自己定：

Now wrap the Angular Heroes in an AngularJS factory function using downgradeInjectable(). and plug the factory into an AngularJS module. The name of the AngularJS dependency is up to you:

import { downgradeInjectable } from '@angular/upgrade/static';
angular.module('heroApp', [])
  .factory('heroes', downgradeInjectable(Heroes))
  .component('heroDetail', heroDetailComponent);

此后，该服务就能被注入到AngularJS代码中的任何地方了：

After this, the service is injectable anywhere in our AngularJS code:

export const heroDetailComponent = {
  template: `
    <h2>{{$ctrl.hero.id}}: {{$ctrl.hero.name}}</h2>
  `,
  controller: ['heroes', function(heroes: Heroes) {
    this.hero = heroes.get()[0];
  }]
};

在混合式应用中使用AOT编译

Using Ahead-of-time compilation with hybrid apps

我们也可以其它Angular应用一样在混合式应用中发挥AOT编译的优势。 对混合式应用的设置过程和预编译章节中所讲的几乎完全一样，不同点在于index.html和main-aot.ts中。

We can take advantage of Ahead-of-time (AoT) compilation on hybrid apps just like on any other Angular application. The setup for an hybrid app is mostly the same as described in the Ahead-of-time Compilation chapter save for differences in index.html and main-aot.ts

我们的index.html仍然需要script标签来加载AngularJS的文件，因此我们使用AOT编译的index.html也需要加载那些文件。 复制它们的简单方案是把它们全都添加到copy-dist-files.js文件中。

Our index.html will likely have script tags loading AngularJS files, so the index.html we use for AoT must also load those files. An easy way to copy them is by adding each to the copy-dist-files.js file.

我们还要使用UpgradeModule在启动了模块工厂之后引导一个混合式应用：

We also need to use UpgradeModule to bootstrap a hybrid app after bootstrapping the Module Factory:

import { platformBrowser } from '@angular/platform-browser';
import { UpgradeModule } from '@angular/upgrade/static';
import { AppModuleNgFactory } from '../aot/app/app.module.ngfactory';
platformBrowser().bootstrapModuleFactory(AppModuleNgFactory).then(platformRef => {
  const upgrade = platformRef.injector.get(UpgradeModule) as UpgradeModule;
  upgrade.bootstrap(document.documentElement, ['phonecatApp']);
});

这就是我们为获取Angular应用的AOT优势所要做的一切。

And that's all we need to get the full benefit of AoT for Angular apps!

在Angular和AngularJS之间划分路由

Dividing routes between Angular and AngularJS

升级中的另一个重要部分是升级路由。 我们固然可以升级整个应用但仍然使用AngularJS的路由器，然后一举把所有路由迁移过去。 但更好地方式是在升级每个路由时逐个把它们迁移过去。

Another important part of upgrading is upgrading routes. We could upgrade our whole app while still using the AngularJS router and then migrate all the routes in one fell swoop. But it would be much better to migrate routes one by one as they become upgraded.

让两个版本的路由器并存的第一步就是为每个路由器添加一个包含单一出口的根组件。 AngularJS将会使用ng-view，而Angular将会使用router-outlet。 当使用其中的一个路由器时，另一个路由出口就是空白的。

The first step to have a dual router setup is to add an Angular root component containing one outlet for each router. AngularJS will use ng-view, and Angular will use router-outlet. When one is using it's router, the other outlet will be empty.

import { Component } from '@angular/core';
@Component({
  selector: 'my-app',
  template: `
    <router-outlet></router-outlet>
    <div ng-view></div>
  `,
})
export class AppComponent { }

我们要在index.html的body中使用该组件来代替AngularJS的组件。

We want to use this component in the body of our index.html instead of an AngularJS component:

<body>
  <my-app>Loading...</my-app>
</body>

接下来，我们用标准方式同时声明AngularJS和Angular的路由：

Next we declare both AngularJS and Angular routes as normal:

$routeProvider
  .when('/villain', { template: '<villain-detail></villain-detail>' });

RouterModule.forChild([
  { path: 'hero', children: [
    { path: '', component: HeroDetailComponent },
  ] },
])

在app.module.ts中，我们需要把AppComponent添加到declarations和bootstrap数组中。

In our app.module.ts we need to add AppComponent to the declarations and boostrap array.

接下来，我们配置路由器本身。 我们要在Angular中使用hash navigation，因为我们也要在AngularJS中使用这种方式。

Next we configure the router itself. We want to use hash navigation in Angular because that's what we're also using in AngularJS.

最后，最重要的是，我们要使用一个自定义的UrlHandlingStrategy，它会告诉Angular路由器应该渲染（且只渲染）哪个路由。

Lastly, and most importantly, we want to use a custom UrlHandlingStrategy that will tell the Angular router which routes it should render - and only those.

import { HashLocationStrategy, LocationStrategy } from '@angular/common';
import { RouterModule, UrlHandlingStrategy, UrlTree } from '@angular/router';
import { AppComponent } from './app.component';
class HybridUrlHandlingStrategy implements UrlHandlingStrategy {
  // use only process the `/hero` url
  shouldProcessUrl(url: UrlTree) { return url.toString().startsWith('/hero'); }
  extract(url: UrlTree) { return url; }
  merge(url: UrlTree, whole: UrlTree) { return url; }
}
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule,
    HeroModule,
    RouterModule.forRoot([])
  ],
  providers: [
    // use hash location strategy
    { provide: LocationStrategy, useClass: HashLocationStrategy },
    // use custom url handling strategy
    { provide: UrlHandlingStrategy, useClass: HybridUrlHandlingStrategy }
  ],
  declarations: [ AppComponent ],
  bootstrap: [ AppComponent ]
})
export class AppModule { }

就这样！现在我们可以同时运行这两个路由器了。

That's it! Now we're running both routers at the same time.

PhoneCat升级教程

PhoneCat Upgrade Tutorial

在本节和下节中，我们将看一个完整的例子，它使用upgrade模块准备和升级了一个应用程序。 该应用就是来自原AngularJS教程中的Angular PhoneCat。 那是我们很多人当初开始Angular探险之旅的起点。 现在，我们来看看如何把该应用带入Angular的美丽新世界。

In this section and we will look at a complete example of preparing and upgrading an application using the upgrade module. The app we're going to work on is Angular PhoneCat from the original AngularJS tutorial, which is where many of us began our Angular adventures. Now we'll see how to bring that application to the brave new world of Angular.

这期间，我们将学到如何在实践中应用准备指南中列出的那些重点步骤： 我们先让该应用向Angular看齐，然后为它引入SystemJS模块加载器和TypeScript。

During the process we'll learn how to apply the steps outlined in the preparation guide in practice: We'll align the application with Angular and also take TypeScript into use.

要跟随本教程，请先把angular-phonecat仓库克隆到本地，并跟我们一起应用这些步骤。

To follow along with the tutorial, clone the angular-phonecat repository and apply the steps as we go.

在项目结构方面，我们工作的起点是这样的：

In terms of project structure, this is where our work begins:

这确实是一个很好地起点。特别是，该结构遵循了AngularJS 风格指南， 要想成功升级，这是一个很重要的准备步骤。

This is actually a pretty good starting point. The code uses the AngularJS 1.5 component API and the organization follows the AngularJS Style Guide, which is an important preparation step before a successful upgrade.

• 每个组件、服务和过滤器都在它自己的源文件中 —— 就像单一规则所要求的。

  Each component, service, and filter is in its own source file, as per the Rule of 1.

• core、phone-detail和phone-list模块都在它们自己的子目录中。那些子目录除了包含HTML模板之外，还包含JavaScript代码，它们共同完成一个特性。 这是按特性分目录的结构 和模块化规则所要求的。

  The core, phone-detail, and phone-list modules are each in their own subdirectory. Those subdirectories contain the JavaScript code as well as the HTML templates that go with each particular feature. This is in line with the Folders-by-Feature Structure and Modularity rules.

• 单元测试都和应用代码在一起，它们很容易找到。就像规则 组织测试文件中要求的那样。

  Unit tests are located side-by-side with application code where they are easily found, as described in the rules for Organizing Tests.

切换到TypeScript

Switching to TypeScript

因为我们将使用TypeScript编写Angular的代码，所以在开始升级之前，我们把TypeScript的编译器设置好是很合理的。

Since we're going to be writing our Angular code in TypeScript, it makes sense to bring in the TypeScript compiler even before we begin upgrading.

我们还将开始逐步淘汰Bower包管理器，换成我们更喜欢的NPM。后面我们将使用NPM来安装新的依赖包，并最终从项目中移除Bower。

We will also start to gradually phase out the Bower package manager in favor of NPM. We'll install all new dependencies using NPM, and will eventually be able to remove Bower from the project.

让我们先把TypeScript包安装到项目中。

Let's begin by installing TypeScript to the project.

npm i typescript --save-dev

我们还要把用来运行TypeScript编译器tsc和typings工具的脚本添加到package.json中：

Let's also add run scripts for the tsc TypeScript compiler to package.json:

{
  "scripts": {}
}

现在我们可以使用typings工具来安装AngularJS和Jasmine单元测试框架的类型定义文件。

We can now install type definitions for the existing libraries that we're using but that don't come with prepackaged types: AngularJS and the Jasmine unit test framework.

npm install @types/jasmine @types/angular  @types/angular-animate @types/angular-cookies @types/angular-mocks @types/angular-resource @types/angular-route @types/angular-sanitize --save-dev

我们还应该配置TypeScript编译器，以便它能理解我们的项目结构。我们要往项目目录下添加一个tsconfig.json文件， 就像在搭建本地开发环境中做过的那样。它将告诉TypeScript编译器，该如何编译我们的源文件。

We should also configure the TypeScript compiler so that it can understand our project. We'll add a tsconfig.json file to the project directory, just like we do in the documentation setup. It instructs the TypeScript compiler how to interpret our source files.

{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "moduleResolution": "node",
    "sourceMap": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "removeComments": false,
    "noImplicitAny": false,
    "suppressImplicitAnyIndexErrors": true
  }
}

我们告诉TypeScript编译器，把TypeScript文件转换成ES5代码，并打包进CommonJS模块中。

We are telling the TypeScript compiler to turn our TypeScript files to ES5 code bundled into CommonJS modules.

我们现在可以从命令行启动TypeScript编译器。它将监控.ts源码文件，并随时把它们编译成JavaScript。 然后这些编译出的.js文件被SystemJS加载到浏览器中。当我们继续往前走的时候，这个过程将在后台持续运行。

We can now launch the TypeScript compiler from the command line. It will watch our .ts source files and compile them to JavaScript on the fly. Those compiled .js files are then loaded into the browser by SystemJS. This is a process we'll want to have continuously running in the background as we go along.

npm run tsc:w

我们要做的下一件事是把JavaScript文件转换成TypeScript文件。 由于TypeScript是ECMAScript 2015的一个超集，而ES2015又是ECMAScript 5的超集，所以我们可以简单的把文件的扩展名从.js换成.ts， 它们还是会像以前一样工作。由于TypeScript编译器仍在运行，它会为每一个.ts文件生成对应的.js文件，而真正运行的是编译后的.js文件。 如果你用npm start开启了本项目的HTTP服务器，你会在浏览器中看到一个功能完好的应用。

The next thing we'll do is convert our JavaScript files to TypeScript. Since TypeScript is a superset of ECMAScript 2015, which in turn is a superset of ECMAScript 5, we can simply switch the file extensions from .js to .ts and everything will work just like it did before. As the TypeScript compiler runs, it emits the corresponding .js file for every .ts file and the compiled JavaScript is what actually gets executed. If you start the project HTTP server with npm start, you should see the fully functional application in your browser.

有了TypeScript，我们就可以从它的一些特性中获益了。此语言可以为AngularJS应用提供很多价值。

Now that we have TypeScript though, we can start benefiting from some of its features. There's a lot of value the language can provide to AngularJS applications.

首先，TypeScript是一个ES2015的超集。任何以前用ES5写的程序(就像PhoneCat范例)都可以开始通过TypeScript 纳入那些添加到ES2015中的新特性。 这包括let、const、箭头函数、函数默认参数以及解构(destructure)赋值。

For one thing, TypeScript is a superset of ES2015. Any app that has previously been written in ES5 - like the PhoneCat example has - can with TypeScript start incorporating all of the JavaScript features that are new to ES2015. These include things like lets and consts, arrow functions, default function parameters, and destructuring assignments.

我们能做的另一件事就是把类型安全添加到代码中。这实际上已经部分完成了，因为我们已经安装了AngularJS的类型定义。 当我们正确调用AngularJS的API时，TypeScript会帮我们检查它 —— 比如往Angular模块中注册组件。

Another thing we can do is start adding type safety to our code. This has actually partially already happened because of the AngularJS typings we installed. TypeScript are checking that we are calling AngularJS APIs correctly when we do things like register components to Angular modules.

我们还能开始把类型注解添加到自己的代码中，来从TypeScript的类型系统中获得更多帮助。 比如，我们可以给checkmark过滤器加上注解，表明它期待一个boolean类型的参数。 这可以更清楚的表明此过滤器打算做什么

But we can also start adding type annotations for our own code to get even more out of TypeScript's type system. For instance, we can annotate the checkmark filter so that it explicitly expects booleans as arguments. This makes it clearer what the filter is supposed to do.

angular.
  module('core').
  filter('checkmark', function() {
    return function(input: boolean) {
      return input ? '\u2713' : '\u2718';
    };
  });

在Phone服务中，我们可以明确的把$resource服务声明为angular.resource.IResourceService，一个AngularJS类型定义提供的类型。

In the Phone service we can explicitly annotate the $resource service dependency as an angular.resource.IResourceService - a type defined by the AngularJS typings.

angular.
  module('core.phone').
  factory('Phone', ['$resource',
    function($resource: angular.resource.IResourceService) {
      return $resource('phones/:phoneId.json', {}, {
        query: {
          method: 'GET',
          params: {phoneId: 'phones'},
          isArray: true
        }
      });
    }
  ]);

我们可以在应用的路由配置中使用同样的技巧，那里我们用到了location和route服务。 一旦给它们提供了类型信息，TypeScript就能检查我们是否在用类型的正确参数来调用它们了。

We can apply the same trick to the application's route configuration file in app.config.ts, where we are using the location and route services. By annotating them accordingly TypeScript can verify we're calling their APIs with the correct kinds of arguments.

angular.
  module('phonecatApp').
  config(['$locationProvider', '$routeProvider',
    function config($locationProvider: angular.ILocationProvider,
                    $routeProvider: angular.route.IRouteProvider) {
      $locationProvider.hashPrefix('!');
      $routeProvider.
        when('/phones', {
          template: '<phone-list></phone-list>'
        }).
        when('/phones/:phoneId', {
          template: '<phone-detail></phone-detail>'
        }).
        otherwise('/phones');
    }
  ]);

我们能用的另一个TypeScript特性是类。具体来讲，我们可以把控制器转换成类。 这种方式下，我们离成为Angular组件类就又近了一步，它会令我们的升级之路变得更简单。

Another TypeScript feature we can make use of is classes. In particular, we can turn our component controllers into classes. That way they'll be a step closer to becoming Angular component classes, which will make our life easier once we do the upgrade.

AngularJS期望控制器是一个构造函数。这实际上就是ES2015/TypeScript中的类， 这也就意味着只要我们把一个类注册为组件控制器，AngularJS就会愉快的使用它。

AngularJS expects controllers to be constructor functions. That's exactly what ES2015/TypeScript classes are under the hood, so that means we can just plug in a class as a component controller and AngularJS will happily use it.

新的“电话列表(phone list)”组件控制器类是这样的：

Here's what our new class for the phone list component controller looks like:

class PhoneListController {
  phones: any[];
  orderProp: string;
  query: string;
  static $inject = ['Phone'];
  constructor(Phone: any) {
    this.phones = Phone.query();
    this.orderProp = 'age';
  }
}
angular.
  module('phoneList').
  component('phoneList', {
    templateUrl: 'phone-list/phone-list.template.html',
    controller: PhoneListController
  });

以前在控制器函数中实现的一切，现在都改由类的构造函数来实现了。类型注入注解通过静态属性$inject 被附加到了类上。在运行时，它们变成了PhoneListController.$inject。

What was previously done in the controller function is now done in the class constructor function. The dependency injection annotations are attached to the class using a static property $inject. At runtime this becomes the PhoneListController.$inject property.

该类还声明了另外三个成员：电话列表、当前排序键的名字和搜索条件。 这些东西我们以前就加到了控制器上，只是从来没有在任何地方显式定义过它们。最后一个成员从未真正在TypeScript代码中用过， 因为它只是在模板中被引用过。但为了清晰起见，我们还是应该定义出此控制器应有的所有成员。

The class additionally declares three members: The array of phones, the name of the current sort key, and the search query. These are all things we have already been attaching to the controller but that weren't explicitly declared anywhere. The last one of these isn't actually used in the TypeScript code since it's only referred to in the template, but for the sake of clarity we want to define all the members our controller will have.

在电话详情控制器中，我们有两个成员：一个是用户正在查看的电话，另一个是正在显示的图像：

In the Phone detail controller we'll have two members: One for the phone that the user is looking at and another for the URL of the currently displayed image:

class PhoneDetailController {
  phone: any;
  mainImageUrl: string;
  static $inject = ['$routeParams', 'Phone'];
  constructor($routeParams: angular.route.IRouteParamsService, Phone: any) {
    let phoneId = $routeParams['phoneId'];
    this.phone = Phone.get({phoneId}, (phone: any) => {
      this.setImage(phone.images[0]);
    });
  }
  setImage(imageUrl: string) {
    this.mainImageUrl = imageUrl;
  }
}
angular.
  module('phoneDetail').
  component('phoneDetail', {
    templateUrl: 'phone-detail/phone-detail.template.html',
    controller: PhoneDetailController
  });

这已经让我们的控制器代码看起来更像Angular了。我们的准备工作做好了，可以引进Angular到项目中了。

This makes our controller code look a lot more like Angular already. We're all set to actually introduce Angular into the project.

如果项目中有任何AngularJS的服务，它们也是转换成类的优秀候选人，像控制器一样，它们也是构造函数。 但是在本项目中，我们只有一个Phone工厂，这有点特别，因为它是一个ngResource工厂。 所以我们不会在准备阶段中处理它，而是在下一节中直接把它转换成Angular服务。

If we had any AngularJS services in the project, those would also be a good candidate for converting to classes, since like controllers, they're also constructor functions. But we only have the Phone factory in this project, and that's a bit special since it's an ngResource factory. So we won't be doing anything to it in the preparation stage. We'll instead turn it directly into an Angular service.

安装Angular

Installing Angular

我们已经完成了准备工作，接下来就开始把PhoneCat升级到Angular。 我们将在Angular升级模块的帮助下增量式的完成此项工作。 等我们完成的那一刻，就能把AngularJS从项目中完全移除了，但其中的关键是在不破坏此程序的前提下一小块一小块的完成它。

Having completed our preparation work, let's get going with the Angular upgrade of PhoneCat. We'll do this incrementally with the help of the upgrade module that comes with Angular. By the time we're done, we'll be able to remove AngularJS from the project completely, but the key is to do this piece by piece without breaking the application.

我们来使用SystemJS模块加载器把Angular安装到项目中。 看看搭建本地开发环境中的指南，并从那里获得如下配置：

Let's install Angular into the project, along with the SystemJS module loader. Take a look at the results of the Setup instructions and get the following configurations from there:

• 把Angular和其它新依赖添加到package.json中

  Add Angular and the other new dependencies to package.json

• 把SystemJS的配置文件systemjs.config.js添加到项目的根目录。

  The SystemJS configuration file systemjs.config.js to the project root directory.

这些完成之后，就运行：

Once these are done, run:

npm install

我们可以通过index.html来把Angular的依赖快速加载到应用中， 但首先，我们得做一些目录结构调整。这是因为我们正准备从node_modules中加载文件，然而目前项目中的每一个文件都是从/app目录下加载的。

We can soon load Angular dependencies into the application via index.html, but first we need to do some directory path adjustments. This is because we're going to need to load files from node_modules and the project root, whereas so far in this project everything has been loaded from the /app directory.

把app/index.html移入项目的根目录，然后把package.json中的开发服务器根目录也指向项目的根目录，而不再是app目录：

Move the app/index.html file to the project root directory. Then change the development server root path in package.json to also point to the project root instead of app:

{
  "scripts": {
    "start": "http-server -a localhost -p 8000 -c-1 ./"
  }
}

现在，我们能把项目根目录下的每一样东西发给浏览器了。但我们不想为了适应开发环境中的设置，被迫修改应用代码中用到的所有图片和数据的路径。因此，我们往index.html中添加一个<base>标签，它将导致各种相对路径被解析回/app目录：

Now we're able to serve everything from the project root to the web browser. But we do not want to have to change all the image and data paths used in the application code to match our development setup. For that reason, we'll add a <base> tag to index.html, which will cause relative URLs to be resolved back to the /app directory:

<base href="/app/">

现在我们可以通过SystemJS加载Angular了。我们将把Angular的填充库(polyfills) 和SystemJS的配置加到<head>区的末尾，然后，我们就用System.import来加载实际的应用：

Now we can load Angular via SystemJS. We'll add the Angular polyfills and the SystemJS config to the end of the <head> section, and then we'll use System.import to load the actual application:

<script src="/node_modules/core-js/client/shim.min.js"></script>
<script src="/node_modules/zone.js/dist/zone.js"></script>
<script src="/node_modules/systemjs/dist/system.src.js"></script>
<script src="/systemjs.config.js"></script>
<script>
  System.import('/app');
</script>

我们还需要对环境设置期间安装的systemjs.config.js文件做一些调整。

We also need to make a couple of adjustments to the systemjs.config.js file installed during setup.

我们要在通过SystemJS加载期间为浏览器指出项目的根在哪里，而不再使用<base> URL。

We want to point the browser to the project root when loading things through SystemJS, instead of using the <base> URL.

我们还要通过npm install @angular/upgrade --save来安装upgrade包，并为@angular/upgrade/static包添加一个映射。

We also need to install the upgrade package via npm install @angular/upgrade --save and add a mapping for the @angular/upgrade/static package.

System.config({
  paths: {
    // paths serve as alias
    'npm:': '/node_modules/'
  },
  map: {
    app: '/app',
    /* . . . */
    '@angular/upgrade/static': 'npm:@angular/upgrade/bundles/upgrade-static.umd.js',
    /* . . . */
  },

创建AppModule

Creating the AppModule

现在，创建一个名叫AppModule的根NgModule类。 我们已经有了一个名叫app.module.ts的文件，其中存放着AngularJS的模块。 把它改名为app.module.ng1.ts，同时也要在index.html中更新对应的脚本名。 文件的内容保留：

Now create the root NgModule class called AppModule. There is already a file named app.module.ts that holds the AngularJS module. Rename it to app.module.ajs.ts and update the corresponding script name in the index.html as well. The file contents remain:

'use strict';
// Define the `phonecatApp` AngularJS module
angular.module('phonecatApp', [
  'ngAnimate',
  'ngRoute',
  'core',
  'phoneDetail',
  'phoneList',
]);

然后创建一个新的app.module.ts文件，其中是一个最小化的NgModule类：

Now create a new app.module.ts with the minimum NgModule class:

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
@NgModule({
  imports: [
    BrowserModule,
  ],
})
export class AppModule {
}

引导PhoneCat的1+2混合式应用

Bootstrapping a hybrid PhoneCat

接下来，我们把该应用程序引导改装为一个同时支持AngularJS和Angular的混合式应用。 然后，就能开始把这些不可分割的小块转换到Angular了。

What we'll do next is bootstrap the application as a hybrid application that supports both AngularJS and Angular components. Once we've done that we can start converting the individual pieces to Angular.

要引导一个混合式应用程序， 我们首先需要在AppModule中导入`UpgradeModule，并覆盖它的启动方法：

To bootstrap a hybrid application, we first need to import UpgradeModule in our AppModule, and override it's bootstrap method:

import { UpgradeModule } from '@angular/upgrade/static';
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule,
  ],
})
export class AppModule {
  ngDoBootstrap() {}
}

我们的应用现在是使用宿主页面中附加到<html>元素上的ng-app指令引导的。 但在Angular中，它不再工作了。我们得切换成JavaScript驱动的引导方式。

Our application is currently bootstrapped using the AngularJS ng-app directive attached to the <html> element of the host page. This will no longer work with Angular. We should switch to a JavaScript-driven bootstrap instead.

所以，从index.html中移除ng-app属性，并把这些加载main.ts中。 在systemjs.config.js中已经将此文件配置为应用的入口，所以它已被浏览器所加载。

So, remove the ng-app attribute from index.html, and instead bootstrap via src/main.ts. This file has been configured as the application entrypoint in systemjs.config.js, so it is already being loaded by the browser.

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { UpgradeModule } from '@angular/upgrade/static';
import { AppModule } from './app.module';
platformBrowserDynamic().bootstrapModule(AppModule).then(platformRef => {
  const upgrade = platformRef.injector.get(UpgradeModule) as UpgradeModule;
  upgrade.bootstrap(document.documentElement, ['phonecatApp']);
});

这里使用的参数是应用的根元素(也就是以前我们放ng-app的元素)，和我们准备加载的AngularJS.x模块。 由于我们是通过UpgradeAdapter引导应用的，所以实际在运行的应用实际上是一个混合体。

The arguments used here are the root element of the application (which is the same element we had ng-app on earlier), and the AngularJS 1.x modules that we want to load. Since we're bootstrapping the app through an UpgradeModule, we're actually now running the app as a hybrid app.

我们现在同时运行着AngularJS和Angular。漂亮！不过我们还没有运行什么实际的Angular组件，接下来我们就做这件事。

This means we are now running both AngularJS and Angular at the same time. That's pretty exciting! We're not running any actual Angular components yet though, so let's do that next.

升级Phone服务

Upgrading the Phone service

我们要移植到Angular的第一块是Phone工厂(位于app/js/core/phones.factory.ts)， 并且让它能帮助控制器从服务器上加载电话信息。目前，它是用ngResource实现的，我们用它做两件事：

The first piece we'll port over to Angular is the Phone service, which resides in app/core/phone/phone.service.ts and makes it possible for components to load phone information from the server. Right now it's implemented with ngResource and we're using it for two things:

• 把所有电话的列表加载到电话列表组件中。

  For loading the list of all phones into the phone list component

• 把一台电话的详情加载到电话详情组件中。

  For loading the details of a single phone into the phone detail component.

我们可以用Angular的服务类来替换这个实现，而把控制器继续留在AngularJS的地盘上。

We can replace this implementation with an Angular service class, while keeping our controllers in AngularJS land.

在这个新版本中，我们导入了Angular的HTTP模块，并且用它的Http服务替换掉NgResource。

In the new version, we import the Angular HTTP module and call its Http service instead of ngResource.

再次打开app.module.ts文件，导入并把HttpModule添加到AppModule的imports数组中：

Re-open the app.module.ts file, import and add HttpModule to the imports array of the AppModule:

import { HttpModule } from '@angular/http';
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule,
    HttpModule,
  ],
})
export class AppModule {
  ngDoBootstrap() {}
}

现在，我们已经准备好了升级Phones服务本身。我们将为phone.service.ts文件中基于ngResource的服务加上@Injectable装饰器：

Now we're ready to upgrade the Phone service itself. We replace the ngResource-based service in phone.service.ts with a TypeScript class decorated as @Injectable:

@Injectable()
export class Phone {
/* . . . */
}

@Injectable装饰器将把一些依赖注入相关的元数据附加到该类上，让Angular知道它的依赖信息。 就像在依赖注入指南中描述过的那样， 这是一个标记装饰器，我们要把它用在那些没有其它Angular装饰器，并且自己有依赖注入的类上。

The @Injectable decorator will attach some dependency injection metadata to the class, letting Angular know about its dependencies. As described by our Dependency Injection Guide, this is a marker decorator we need to use for classes that have no other Angular decorators but still need to have their dependencies injected.

在它的构造函数中，该类期待一个Http服务。Http服务将被注入进来并存入一个私有字段。 然后该服务在两个实例方法中被使用到，一个加载所有电话的列表，另一个加载一台指定电话的详情：

In its constructor the class expects to get the Http service. It will be injected to it and it is stored as a private field. The service is then used in the two instance methods, one of which loads the list of all phones, and the other the details of a particular phone:

@Injectable()
export class Phone {
  constructor(private http: Http) { }
  query(): Observable<PhoneData[]> {
    return this.http.get(`phones/phones.json`)
      .map((res: Response) => res.json());
  }
  get(id: string): Observable<PhoneData> {
    return this.http.get(`phones/${id}.json`)
      .map((res: Response) => res.json());
  }
}

该方法现在返回一个Phone类型或Phone[]类型的可观察对象(Observable)。 这是一个我们从未用过的类型，因此我们得为它新增一个简单的接口：

The methods now return Observables of type PhoneData and PhoneData[]. This is a type we don't have yet, so let's add a simple interface for it:

export interface PhoneData {
  name: string;
  snippet: string;
  images: string[];
}

@angular/upgrade/static有一个downgradeInjectable方法，可以使Angular服务在AngularJS的代码中可用。 使用它来插入Phone服务：

@angular/upgrade/static has a downgradeInjectable method for the purpose of making Angular services available to AngularJS code. Use it to plug in the Phone service:

declare var angular: angular.IAngularStatic;
import { downgradeInjectable } from '@angular/upgrade/static';
/* . . . */
@Injectable()
export class Phone {
/* . . . */
}

angular.module('core.phone')
  .factory('phone', downgradeInjectable(Phone));

最终，该类的全部代码如下：

Here's the full, final code for the service:

import { Injectable } from '@angular/core';
import { Http, Response } from '@angular/http';
import { Observable } from 'rxjs/Rx';
declare var angular: angular.IAngularStatic;
import { downgradeInjectable } from '@angular/upgrade/static';
import 'rxjs/add/operator/map';
export interface PhoneData {
  name: string;
  snippet: string;
  images: string[];
}
@Injectable()
export class Phone {
  constructor(private http: Http) { }
  query(): Observable<PhoneData[]> {
    return this.http.get(`phones/phones.json`)
      .map((res: Response) => res.json());
  }
  get(id: string): Observable<PhoneData> {
    return this.http.get(`phones/${id}.json`)
      .map((res: Response) => res.json());
  }
}
angular.module('core.phone')
  .factory('phone', downgradeInjectable(Phone));

注意，我们单独导入了RxJS Observable中的map操作符。 我们需要对想用的所有RxJS操作符这么做，因为Angular默认不会加载所有RxJS操作符。

Notice that we're importing the map operator of the RxJS Observable separately. We need to do this for all RxJS operators that we want to use, since Angular does not load all of them by default.

这个新的Phone服务具有和老的基于ngResource的服务相同的特性。 因为它是Angular服务，我们通过NgModule的providers数组来注册它：

The new Phone service has the same features as the original, ngResource-based service. Because it's an Angular service, we register it with the NgModule providers:

import { Phone } from './core/phone/phone.service';
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule,
    HttpModule,
  ],
  providers: [
    Phone,
  ]
})
export class AppModule {
  ngDoBootstrap() {}
}

现在，我们正在用SystemJS加载phone.service.ts，我们应该从index.html中移除该服务的<script>标签。 这也是我们在升级所有组件时将会做的事。在从AngularJS向2升级的同时，我们也把代码从脚本移植为模块。

Now that we are loading phone.service.ts through an import that is resolved by SystemJS, we should remove the <script> tag for the service from index.html. This is something we'll do to all our components as we upgrade them. Simultaneously with the AngularJS to Angular upgrade we're also migrating our code from scripts to modules.

这时，我们可以把两个控制器从使用老的服务切换成使用新的。我们像降级过的phones工厂一样$inject它， 但它实际上是一个Phones类的实例，并且我们可以据此注解它的类型：

At this point we can switch our two components to use the new service instead of the old one. We $inject it as the downgraded phone factory, but it's really an instance of the Phone class and we can annotate its type accordingly:

declare var angular: angular.IAngularStatic;
import { Phone, PhoneData } from '../core/phone/phone.service';
class PhoneListController {
  phones: PhoneData[];
  orderProp: string;
  static $inject = ['phone'];
  constructor(phone: Phone) {
    phone.query().subscribe(phones => {
      this.phones = phones;
    });
    this.orderProp = 'age';
  }
}
angular.
  module('phoneList').
  component('phoneList', {
    templateUrl: 'app/phone-list/phone-list.template.html',
    controller: PhoneListController
  });

declare var angular: angular.IAngularStatic;
import { Phone, PhoneData } from '../core/phone/phone.service';
class PhoneDetailController {
  phone: PhoneData;
  mainImageUrl: string;
  static $inject = ['$routeParams', 'phone'];
  constructor($routeParams: angular.route.IRouteParamsService, phone: Phone) {
    let phoneId = $routeParams['phoneId'];
    phone.get(phoneId).subscribe(data => {
      this.phone = data;
      this.setImage(data.images[0]);
    });
  }
  setImage(imageUrl: string) {
    this.mainImageUrl = imageUrl;
  }
}
angular.
  module('phoneDetail').
  component('phoneDetail', {
    templateUrl: 'phone-detail/phone-detail.template.html',
    controller: PhoneDetailController
  });

这里的两个AngularJS控制器在使用Angular的服务！控制器不需要关心这一点，尽管实际上该服务返回的是可观察对象(Observable)，而不是承诺(Promise)。 无论如何，我们达到的效果都是把服务移植到Angular，而不用被迫移植组件来使用它。

What we have here are two AngularJS components using an Angular service! The components don't need to be aware of this, though the fact that the service returns Observables and not Promises is a bit of a giveaway. In any case, what we've achieved is a migration of a service to Angular without having to yet migrate the components that use it.

升级组件

Upgrading Components

接下来，我们把AngularJS的控制器升级成Angular的组件。我们每次升级一个，同时仍然保持应用运行在混合模式下。 在做转换的同时，我们还将自定义首个Angular管道。

Next, let's upgrade our AngularJS components to Angular components. We'll do it one at a time, while still keeping the application in hybrid mode. As we make these conversions, we'll also be defining our first Angular pipes.

让我们先看看电话列表组件。它目前包含一个TypeScript控制器类和一个组件定义对象。重命名控制器类， 并把AngularJS的组件定义对象更换为Angular @Component装饰器，这样我们就把它变形为Angular 的组件了。然后，我们还从类中移除静态$inject属性。

Let's look at the phone list component first. Right now it contains a TypeScript controller class and a component definition object. We can morph this into an Angular component by just renaming the controller class and turning the AngularJS component definition object into an Angular @Component decorator. We can then also remove the static $inject property from the class:

import { Component } from '@angular/core';
import { Phone, PhoneData } from '../core/phone/phone.service';
@Component({
  selector: 'phone-list',
  templateUrl: 'phone-list.template.html'
})
export class PhoneListComponent {
  phones: PhoneData[];
  query: string;
  orderProp: string;
  constructor(phone: Phone) {
    phone.query().subscribe(phones => {
      this.phones = phones;
    });
    this.orderProp = 'age';
  }
  /* . . . */
}

selector属性是一个CSS选择器，用来定义组件应该被放在页面的哪。在AngularJS，我们基于组件名字来匹配， 但是在Angular中，我们要有一个专门指定的选择器。本组件将会对应元素名字phone-list，和AngularJS版本一样。

The selector attribute is a CSS selector that defines where on the page the component should go. In AngularJS we do matching based on component names, but in Angular we have these explicit selectors. This one will match elements with the name phone-list, just like the AngularJS version did.

现在，我们还需要将组件的模版也转换为Angular语法。在搜索控件中，我们要为把AngularJS的$ctrl表达式替换成Angular的双向绑定语法[(ngModel)]：

We now also need to convert the template of this component into Angular syntax. The search controls replace the AngularJS $ctrl expressions with Angular's two-way [(ngModel)] binding syntax:

<p>
  Search:
  <input [(ngModel)]="query" />
</p>

<p>
  Sort by:
  <select [(ngModel)]="orderProp">
    <option value="name">Alphabetical</option>
    <option value="age">Newest</option>
  </select>
</p>

我们需要把列表中的ng-repeat替换为*ngFor以及它的let var of iterable语法， 该语法在模板语法指南中讲过。 对于图片，我们可以把img标签的ng-src替换为一个标准的src属性(property)绑定。

Replace the list's ng-repeat with an *ngFor as described in the Template Syntax page. Replace the image tag's ng-src with a binding to the native src property.

<ul class="phones">
  <li *ngFor="let phone of getPhones()"
      class="thumbnail phone-list-item">
    <a href="/#!/phones/{{phone.id}}" class="thumb">
      <img [src]="phone.imageUrl" [alt]="phone.name" />
    </a>
    <a href="/#!/phones/{{phone.id}}" class="name">{{phone.name}}</a>
    <p>{{phone.snippet}}</p>
  </li>
</ul>

Angular中没有filter或orderBy过滤器

No Angular filter or orderBy filters

Angular中并不存在AngularJS中内置的filter和orderBy过滤器。 所以我们得自己实现进行过滤和排序。

The built-in AngularJS filter and orderBy filters do not exist in Angular, so we need to do the filtering and sorting ourselves.

我们把filter和orderBy过滤器改成绑定到控制器中的getPhones()方法，通过该方法，组件本身实现了过滤和排序逻辑。

We replaced the filter and orderBy filters with bindings to the getPhones() controller method, which implements the filtering and ordering logic inside the component itself.

getPhones(): PhoneData[] {
  return this.sortPhones(this.filterPhones(this.phones));
}
private filterPhones(phones: PhoneData[]) {
  if (phones && this.query) {
    return phones.filter(phone => {
      let name = phone.name.toLowerCase();
      let snippet = phone.snippet.toLowerCase();
      return name.indexOf(this.query) >= 0 || snippet.indexOf(this.query) >= 0;
    });
  }
  return phones;
}
private sortPhones(phones: PhoneData[]) {
  if (phones && this.orderProp) {
    return phones
      .slice(0) // Make a copy
      .sort((a, b) => {
        if (a[this.orderProp] < b[this.orderProp]) {
          return -1;
        } else if ([b[this.orderProp] < a[this.orderProp]]) {
          return 1;
        } else {
          return 0;
        }
      });
  }
  return phones;
}