架构篇翻了一半儿

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Angular 2 is a framework to help us build client applications in HTML and JavaScript. Angular 2 is a framework to help us build client applications in HTML and JavaScript.
Angular 2是一个使用HTML和JavaScript构建客户端应用的框架。
The framework consists of several cooperating libraries, some of them core and some optional. The framework consists of several cooperating libraries, some of them core and some optional.
这个框架包括一系列紧密合作的库,有些是核心库,有些是可选库。
We write applications by composing HTML *templates* with Angularized-markup, We write applications by composing HTML *templates* with Angularized-markup,
writing *component* classes to manage those templates, adding application logic in *services*, writing *component* classes to manage those templates, adding application logic in *services*,
and handing the top root component to Angular's *bootstrapper*. and handing the top root component to Angular's *bootstrapper*.
我们用带有Angular标记的HTML写 *模板* ,用 *组件* 类来管理这些模板,用 *服务* 添加应用逻辑用根组件来完成Angular *启动* 。
把这些组合起来,我们就得到了一个应用程序。
Angular takes over, presenting our application content in a browser and responding to user interactions Angular takes over, presenting our application content in a browser and responding to user interactions
according to the instructions we provided. according to the instructions we provided.
Angular在浏览器中接管、展现我们的应用内容并且根据我们提供的指令响应用户的交互。
<!-- figure img(src="/resources/images/devguide/architecture/airplane.png" alt="Us" align="left" style="width:200px; margin-left:-40px;margin-right:10px" ) --> <!-- figure img(src="/resources/images/devguide/architecture/airplane.png" alt="Us" align="left" style="width:200px; margin-left:-40px;margin-right:10px" ) -->
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Of course there is more to it than this. We'll learn the details when we dive into the guide chapters. Of course there is more to it than this. We'll learn the details when we dive into the guide chapters.
Let's get the big picture first. Let's get the big picture first.
当然,这只是冰山一角。随着内容的深入,我们还会学到更多的细节。
我们先来看看宏观图景。
figure figure
img(src="/resources/images/devguide/architecture/overview2.png" alt="overview" style="margin-left:-40px;" width="700") img(src="/resources/images/devguide/architecture/overview2.png" alt="overview" style="margin-left:-40px;" width="700")
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The architecture diagram identifies the eight main building blocks of an Angular 2 application: The architecture diagram identifies the eight main building blocks of an Angular 2 application:
这个架构图展现了Angular应用中的8个主要构造块
1. [Module](#module) 1. [Module](#module)
1. [模块(Module)](#module)
1. [Component](#component) 1. [Component](#component)
1. [组件(Component)](#component)
1. [Template](#template) 1. [Template](#template)
1. [模板(Template)](#template)
1. [Metadata](#metadata) 1. [Metadata](#metadata)
1. [元数据(Metadata)](#metadata)
1. [Data Binding](#data-binding) 1. [Data Binding](#data-binding)
1. [数据绑定(Data Binding)](#data-binding)
1. [Service](#service) 1. [Service](#service)
1. [服务(Service)](#service)
1. [Directive](#directive) 1. [Directive](#directive)
1. [指令(Directive)](#directive)
1. [Dependency Injection](#dependency-injection) 1. [Dependency Injection](#dependency-injection)
1. [依赖注入(Dependency Injection)](#dependency-injection)
Learn these eight and we're on our way. Learn these eight and we're on our way.
我们这一路上就将学习这8点。
.l-sub-section .l-sub-section
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The code referenced in this chapter is available as a [live example](/resources/live-examples/architecture/ts/plnkr.html). The code referenced in this chapter is available as a [live example](/resources/live-examples/architecture/ts/plnkr.html).
本章所引用的代码可以在这个[鲜活范例](/resources/live-examples/architecture/ts/plnkr.html)中找到。
<a id="module"></a> <a id="module"></a>
.l-main-section .l-main-section
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## The Module ## The Module
## 模块
figure figure
img(src="/resources/images/devguide/architecture/module.png" alt="Component" align="left" style="width:240px; margin-left:-40px;margin-right:10px" ) img(src="/resources/images/devguide/architecture/module.png" alt="模块" align="left" style="width:240px; margin-left:-40px;margin-right:10px" )
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Angular apps are modular. Angular apps are modular.
Angular应用是模块化的。
In general we assemble our application from many **modules**. In general we assemble our application from many **modules**.
我们的程序通常都是由很多 *模块* 组装成的。
A typical module is a cohesive block of code dedicated to a single purpose. A typical module is a cohesive block of code dedicated to a single purpose.
A module **exports** something of value in that code, typically one thing such as a class. A module **exports** something of value in that code, typically one thing such as a class.
典型的组件是一个内聚的代码块组成的,用以完成单一的目的。
<br clear="all"><br> <br clear="all"><br>
.l-sub-section .l-sub-section
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### Modules are optional ### Modules are optional
### 组件是可选的
We highly recommend modular design. TypeScript has great support for ES2015 module syntax and our chapters assume we're taking a modular We highly recommend modular design. TypeScript has great support for ES2015 module syntax and our chapters assume we're taking a modular
approach using that syntax. That's why we list *Module* among the basic building blocks. approach using that syntax. That's why we list *Module* among the basic building blocks.
我们强烈推荐遵循模块化设计。TypeScript对ES2015的模块语法支持很好本章假定我们使用那些语法作为模块化方案。这就是为什么我们要把 *模块* 列为一种基本构造块。
Angular itself doesn't require a modular approach nor this particular syntax. Don't use it if you don't want it. Angular itself doesn't require a modular approach nor this particular syntax. Don't use it if you don't want it.
Each chapter has plenty to offer after you steer clear of the `import` and `export` statements. Each chapter has plenty to offer after you steer clear of the `import` and `export` statements.
Angular本身并不需要模块化方案或使用这种特定的语法。如果你不喜欢可以不用它。
在你弄清楚了`import`和`export`语句之后,它在每章都会出现很多。
Find setup and organization clues in the JavaScript track (select it from the combo-box at the top of this page) Find setup and organization clues in the JavaScript track (select it from the combo-box at the top of this page)
which demonstrates Angular 2 development with plain old JavaScript and no module system. which demonstrates Angular 2 development with plain old JavaScript and no module system.
在JavaScript可以从页面顶部的组合框选择它分支下可以找到如何安装和进行文件组织的线索。
它示范了如何用老版本的JavaScript语言在没有模块化系统的情况下进行Angular 2开发。
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Perhaps the first module we meet is a module that exports a *component* class. Perhaps the first module we meet is a module that exports a *component* class.
The component is one of the basic Angular blocks, we write a lot of them, The component is one of the basic Angular blocks, we write a lot of them,
and we'll talk about components in the next segment. For the moment it is enough to know that a and we'll talk about components in the next segment. For the moment it is enough to know that a
component class is the kind of thing we'd export from a module. component class is the kind of thing we'd export from a module.
也许我们遇到的第一个模块,就是用于导出 *组件* 类的那个。
组件是Angular最基本的构造块之一我们会写很多。下一段我们将会讨论组件。
但目前,只要知道组件类需要我们从模块中导出就行了。
Most applications have an `AppComponent`. By convention, we'll find it in a file named `app.component.ts`. Most applications have an `AppComponent`. By convention, we'll find it in a file named `app.component.ts`.
Look inside such a file and we'll see an `export` statement like this one. Look inside such a file and we'll see an `export` statement like this one.
+makeExample('architecture/ts/app/app.component.ts', 'export', 'app/app.component.ts (excerpt)')(format=".")
大多数应用都有一个`AppComponent`。作为一项惯例,它会位于一个名叫`app.component.ts`的文件中。
打开它,我们将会看到一个`export`语句,就像这样:
+makeExample('architecture/ts/app/app.component.ts', 'export', 'app/app.component.ts (节选)')(format=".")
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The `export` statement tells TypeScript that this is a module whose The `export` statement tells TypeScript that this is a module whose
`AppComponent` class is public and accessible to other modules of the application. `AppComponent` class is public and accessible to other modules of the application.
`export`语句告诉TypeScript这是一个模块`AppComponent`类是公开的,可以被应用中的其它模块访问。
When we need a reference to the `AppComponent`, we **import** it like this: When we need a reference to the `AppComponent`, we **import** it like this:
+makeExample('architecture/ts/app/main.ts', 'import', 'app/main.ts (excerpt)')(format=".")
当我们需要引用`AppComponent`时,我们 **导入** 它,就像这样:
+makeExample('architecture/ts/app/main.ts', 'import', 'app/main.ts (节选)')(format=".")
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The `import` statement tells the system it can get an `AppComponent` from a module named `app.component` The `import` statement tells the system it can get an `AppComponent` from a module named `app.component`
located in a neighboring file. located in a neighboring file.
The **module name** (AKA module id) is often the same as the filename without its extension. The **module name** (AKA module id) is often the same as the filename without its extension.
`import`语句告诉系统,它能从附近一个叫作`app.component`的文件中获得一个`AppComponent`组件。
**模块名** 又叫模块ID通常和去掉扩展名后的文件名相同。
### Library Modules ### Library Modules
### 库模块
figure figure
img(src="/resources/images/devguide/architecture/library-module.png" alt="Component" align="left" style="width:240px; margin-left:-40px;margin-right:10px" ) img(src="/resources/images/devguide/architecture/library-module.png" alt="组件" align="left" style="width:240px; margin-left:-40px;margin-right:10px" )
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Some modules are libraries of other modules. Some modules are libraries of other modules.
有些模块是其它模块的库。
Angular itself ships as a collection of library modules called "barrels". Angular itself ships as a collection of library modules called "barrels".
Each Angular library is actually a public façade over several logically related private modules. Each Angular library is actually a public façade over several logically related private modules.
Angular本身就是用一组库模块的形式发布的我们称之为“封装桶(barrel)”。
每个Angular库实际上是一个公开的外观层façade囊括了许多逻辑上相关的私有模块。
The `angular2/core` library is the primary Angular library module from which we get most of what we need. The `angular2/core` library is the primary Angular library module from which we get most of what we need.
`angular2/core`库是主要的Angular库模块从这里我们能获得所需的大部分东西。
<br clear="all"> <br clear="all">
There are other important Angular library modules too such as `angular2/common`, `angular2/router`, and `angular2/http`. There are other important Angular library modules too such as `angular2/common`, `angular2/router`, and `angular2/http`.
还有其它重要的Angular库比如`angular2/common`, `angular2/router` 和 `angular2/http`。
.l-sub-section .l-sub-section
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Learn more about how Angular organizes and distributes modules Learn more about how Angular organizes and distributes modules
in "[Modules, barrels and bundles](https://github.com/angular/angular/blob/master/modules/angular2/docs/bundles/overview.md)". in "[Modules, barrels and bundles](https://github.com/angular/angular/blob/master/modules/angular2/docs/bundles/overview.md)".
要学习Angular如何组织和分发模块的知识参见"[模块、封装桶(barrel)和捆绑包(bundle)](https://github.com/angular/angular/blob/master/modules/angular2/docs/bundles/overview.md)"
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We import what we need from an Angular library module in much the same way. We import what we need from an Angular library module in much the same way.
For example, we import the Angular **`Component` *function*** from the *angular2/core* module like this: For example, we import the Angular **`Component` *function*** from the *angular2/core* module like this:
我们从Angular库模块中导入的方式基本上都是如此。
比如,我们从 *angular2/core* 中导入Angular **`Component` *函数* ** 的代码是这样的:
+makeExample('architecture/ts/app/app.component.ts', 'import')(format=".") +makeExample('architecture/ts/app/app.component.ts', 'import')(format=".")
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Compare that syntax to our previous import of `AppComponent`. Compare that syntax to our previous import of `AppComponent`.
比较一下它和前面导入`AppComponent`时的语法。
+makeExample('architecture/ts/app/main.ts', 'import')(format=".") +makeExample('architecture/ts/app/main.ts', 'import')(format=".")
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Notice the difference? Notice the difference?
In the first case, when importing from an Angular library module, In the first case, when importing from an Angular library module,
the import statement refers to the bare module name, `angular2/core`, *without a path prefix*. the import statement refers to the bare module name, `angular2/core`, *without a path prefix*.
注意到不同之处了吗?
前面的方式中当从Angular库模块中导入时import语句引用的是一个裸模块名 —— `angular2/core` —— *没有路径前缀* 。
When we import from one of *our* own files, we prefix the module name with the file path. When we import from one of *our* own files, we prefix the module name with the file path.
In this example we specify a relative file path (./). That means the In this example we specify a relative file path (./). That means the
source module is in the same folder (./) as the module importing it. source module is in the same folder (./) as the module importing it.
We could path up and around the application folder structure if the source module were somewhere else. We could path up and around the application folder structure if the source module were somewhere else.
当我们从 *自己的* 文件中导入时,模块名中带有前缀,在这个例子中,是一个相对路径(./)。这表示源模块位于与导入它的模块相同的目录中(./)。
如果源模块位于其它位置的话,我们还可以向上引用应用目录结构中的任意路径(../../../somewhere/)。
.l-sub-section .l-sub-section
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We import and export in the ECMAScript 2015 (ES2015) module syntax. We import and export in the ECMAScript 2015 (ES2015) module syntax.
Learn more about that syntax [here](http://www.2ality.com/2014/09/es6-modules-final.html) Learn more about that syntax [here](http://www.2ality.com/2014/09/es6-modules-final.html)
and many other places on the web. and many other places on the web.
我们导入和导出使用的是ECMAScript 2015 (ES2015)的语法。
要学习更多关于此语法的知识,参见[这里](http://www.2ality.com/2014/09/es6-modules-final.html),也可以在网上的很多地方找到。
The infrastructure *behind* module loading and importing is an important subject. The infrastructure *behind* module loading and importing is an important subject.
But it's a subject outside the scope of this introduction to Angular. But it's a subject outside the scope of this introduction to Angular.
While we're focused on our application, *import* and *export* While we're focused on our application, *import* and *export*
is about all we need to know. is about all we need to know.
关于模块加载和导入背后的基础设施,是一个很重要的话题。
但是这个话题在介绍Angular的范围之外。在我们聚焦于讲解应用的时候知道 *import* 和 *export* 就足够了。
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The key take-aways are: The key take-aways are:
要知道的关键是:
* Angular apps are composed of modules. * Angular apps are composed of modules.
* Angular应用是由模块组成的。
* Modules export things &mdash; classes, function, values &mdash; that other modules import. * Modules export things &mdash; classes, function, values &mdash; that other modules import.
* 模块导出一些东西 —— 类,函数,值,供其它模块导入。
* We prefer to write our application as a collection of modules, each module exporting one thing. * We prefer to write our application as a collection of modules, each module exporting one thing.
* 我们喜欢把应用写成一组模块,每个模块只导出一个东西。
The first module we write will most likely export a component. The first module we write will most likely export a component.
我们写的第一个模块很可能是导出一个组件。
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<a id="component"></a> <a id="component"></a>
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## The Component ## The Component
## 组件
figure figure
img(src="/resources/images/devguide/architecture/hero-component.png" alt="Component" align="left" style="width:200px; margin-left:-40px;margin-right:10px" ) img(src="/resources/images/devguide/architecture/hero-component.png" alt="组件" align="left" style="width:200px; margin-left:-40px;margin-right:10px" )
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A **Component** controls a patch of screen real estate that we could call a *view*. A **Component** controls a patch of screen real estate that we could call a *view*.
The shell at the application root with navigation links, that list of heroes, the hero editor ... The shell at the application root with navigation links, that list of heroes, the hero editor ...
they're all views controlled by Components. they're all views controlled by Components.
**组件** 控制屏幕中的补丁大的一小块儿地方,我们称之为 *视图* 。
应用的“外壳”包括一些导航链接、一个英雄列表、英雄编辑器…… 它们都是被组件控制的视图。
We define a Component's application logic - what it does to support the view - inside a class. We define a Component's application logic - what it does to support the view - inside a class.
The class interacts with the view through an API of properties and methods. The class interacts with the view through an API of properties and methods.
我们定义了一个组件的应用逻辑 —— 它被用来为视图提供支持 —— 放在类中。
组件用一些由属性和方法组成的API与视图交互。
<a id="component-code"></a> <a id="component-code"></a>
A `HeroListComponent`, for example, might have a `heroes` property that returns an array of heroes A `HeroListComponent`, for example, might have a `heroes` property that returns an array of heroes
that it acquired from a service. that it acquired from a service.
It might have a `selectHero()` method that sets a `selectedHero` property when the user clicks on a hero from that list. It might have a `selectHero()` method that sets a `selectedHero` property when the user clicks on a hero from that list.
It might be a class like this: It might be a class like this:
<a id="component-code"></a>
比如,`HeroListComponent`组件,可能有一个`heroes`属性,它返回一个英雄的数组,这个数据是从服务中取得的。
它还可能有一个`selectHero()`方法,用来在用户从列表中点击一个英雄时设置`selectedHero`属性。
它可能是像这样的一个类:
+makeExample('architecture/ts/app/hero-list.component.ts', 'class', 'app/hero-list.component.ts') +makeExample('architecture/ts/app/hero-list.component.ts', 'class', 'app/hero-list.component.ts')
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Angular creates, updates, and destroys components as the user moves through the application. Angular creates, updates, and destroys components as the user moves through the application.
The developer can take action at each moment in this lifecycle through optional [Lifecycle Hooks](lifecycle-hooks.html). The developer can take action at each moment in this lifecycle through optional [Lifecycle Hooks](lifecycle-hooks.html).
当用户在这个应用中“移动”时Angular会创建、更新、销毁组件。
开发人员还可以通过[生命周期钩子](lifecycle-hooks.html)在组件生命周期的每个时间点做出自己的处理。
.l-sub-section .l-sub-section
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We're not showing those hooks in this example We're not showing those hooks in this example
but we are making a mental note to find out about them later. but we are making a mental note to find out about them later.
我们不会在这个例子中展示这些钩子,先在脑子中留个记号,将来再翻出来讲。
We may wonder who is calling that constructor? Who provides the service parameter? We may wonder who is calling that constructor? Who provides the service parameter?
For the moment, have faith that Angular will call the constructor and deliver an For the moment, have faith that Angular will call the constructor and deliver an
appropriate `HeroService` when we need it. appropriate `HeroService` when we need it.
我们可能会好奇,谁调用那个构造函数?谁为服务提供参数?
现在只要相信Angular就行了它会去调用构造函数并且在我们需要的时候交给我们一个合适的`HeroService`实例。
.l-main-section .l-main-section
<a id="template"></a> <a id="template"></a>
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## The Template ## The Template
## 模板
figure figure
img(src="/resources/images/devguide/architecture/template.png" alt="Template" align="left" style="width:200px; margin-left:-40px;margin-right:10px" ) img(src="/resources/images/devguide/architecture/template.png" alt="模板" align="left" style="width:200px; margin-left:-40px;margin-right:10px" )
:marked :marked
We define a Component's view with its companion **template**. A template is a form of HTML We define a Component's view with its companion **template**. A template is a form of HTML
that tells Angular how to render the Component. that tells Angular how to render the Component.
我们通过伴随它的 **模板** 来定义组件的视图。模板是HTML的一种形式用来告诉Angular如何渲染组件。
A template looks like regular HTML much of the time ... and then it gets a bit strange. Here is a A template looks like regular HTML much of the time ... and then it gets a bit strange. Here is a
template for our `HeroList` component. template for our `HeroList` component.
基本上模板看起来很像标准HTML……当然也略有一些奇怪的地方。下面是我们`HeroList`组件的一个模板。
+makeExample('architecture/ts/app/hero-list.component.html',null,'app/hero-list.component.html') +makeExample('architecture/ts/app/hero-list.component.html',null,'app/hero-list.component.html')
:marked :marked
We recognize `<h2>` and `<div>`. We recognize `<h2>` and `<div>`.
But there's other markup that no one told us about in school. But there's other markup that no one told us about in school.
What are `*ngFor`, `{{hero.name}}`, `(click)`, `[hero]`, and `<hero-detail>`? What are `*ngFor`, `{{hero.name}}`, `(click)`, `[hero]`, and `<hero-detail>`?
我们认得`<h2>`和`<div>`。
但有一些其他的标签/属性是我们在学校中从没有听说过的。
什么是`*ngFor`、`{{hero.name}}`、`(click)`、`[hero]`和`<hero-detail>`
These are examples of Angular's [template syntax](template-syntax.html). These are examples of Angular's [template syntax](template-syntax.html).
We will grow accustomed to that syntax and may even learn to love it. We will grow accustomed to that syntax and may even learn to love it.
We'll begin to explain it in a moment. We'll begin to explain it in a moment.
这些是Angular [模板语法](template-syntax.html) 的例子。
我们会逐步习惯这些语法,甚至会学着爱上它。
一会儿我们再解释它。
Before we do, focus attention on the last line. Before we do, focus attention on the last line.
The `<hero-detail>` tag is a custom element representing the `HeroDetailComponent`. The `<hero-detail>` tag is a custom element representing the `HeroDetailComponent`.
在我们开始前,注意最后那行。
`<hero-detail>`是一个自定义元素的标签,用来表示`HeroDetailComponent`组件。
The `HeroDetailComponent` is a *different* component than the `HeroListComponent` we've been reviewing. The `HeroDetailComponent` is a *different* component than the `HeroListComponent` we've been reviewing.
The `HeroDetailComponent` (code not shown) presents facts about a particular hero, the The `HeroDetailComponent` (code not shown) presents facts about a particular hero, the
hero that the user selects from the list presented by the `HeroListComponent`. hero that the user selects from the list presented by the `HeroListComponent`.
The `HeroDetailComponent` is a **child** of the `HeroListComponent`. The `HeroDetailComponent` is a **child** of the `HeroListComponent`.
`HeroDetailComponent`是和我们审视过的`HeroListComponent` *不同* 的组件。
`HeroDetailComponent`(未展示代码)展现一个特定英雄的情况,这个英雄是用户从`HeroListComponent`所展示的列表中选择的。
`HeroDetailComponent`是`HeroListComponent`的 *子组件* 。
figure figure
img(src="/resources/images/devguide/architecture/component-tree.png" alt="Metadata" align="left" style="width:300px; margin-left:-40px;margin-right:10px" ) img(src="/resources/images/devguide/architecture/component-tree.png" alt="组件树" align="left" style="width:300px; margin-left:-40px;margin-right:10px" )
:marked :marked
Notice how `<hero-detail>` rests comfortably among the HTML elements we already know. Notice how `<hero-detail>` rests comfortably among the HTML elements we already know.
We can mix ... and will mix ... our custom components with native HTML in the same layouts. We can mix ... and will mix ... our custom components with native HTML in the same layouts.
注意:`<hero-detail>`是多么和谐的出现在我们已经知道的那些HTML元素中。
我们在同一个布局中可以混合……而且还将混合……我们的自定义组件与原生HTML。
And in this manner we can and will compose complex component trees to build out our richly featured application. And in this manner we can and will compose complex component trees to build out our richly featured application.
在这种方式下,我们能而且将会组合出复杂的组件树,来构建我们那些丰富多彩的应用。
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.l-main-section .l-main-section
<a id="metadata"></a> <a id="metadata"></a>
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## Angular Metadata ## Angular Metadata
## Angular元数据
figure figure
img(src="/resources/images/devguide/architecture/metadata.png" alt="Metadata" align="left" style="width:150px; margin-left:-40px;margin-right:10px" ) img(src="/resources/images/devguide/architecture/metadata.png" alt="元数据" align="left" style="width:150px; margin-left:-40px;margin-right:10px" )
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<p style="padding-top:10px">Metadata tells Angular how to process a class.</p> <p style="padding-top:10px">Metadata tells Angular how to process a class.</p>
<p style="padding-top:10px">元数据告诉Angular如何处理一个类。</p>
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[Looking back](#component-code) at the `HeroListComponent`, we see that it's just a class. [Looking back](#component-code) at the `HeroListComponent`, we see that it's just a class.
There is no evidence of a framework, no "Angular" in it at all. There is no evidence of a framework, no "Angular" in it at all.
[回头看看](#component-code)`HeroListComponent`,我们就明白,它只是一个类。
毫无框架的迹象,里面完全没有出现"Angular"。
In fact, it really is *just a class*. It's not a component until we *tell Angular about it*. In fact, it really is *just a class*. It's not a component until we *tell Angular about it*.
实际上,它真的只是一个类。直到我们 *告诉Angular这一点* ,否则就没有组件。
We tell Angular that `HeroListComponent` is a component by attaching **metadata** to the class. We tell Angular that `HeroListComponent` is a component by attaching **metadata** to the class.
通过把 **元数据** 附加到类我们告诉Angular`HeroListComponent`是个组件。
The easy way to attach metadata in TypeScript is with a **decorator**. The easy way to attach metadata in TypeScript is with a **decorator**.
Here's some metadata for `HeroListComponent`: Here's some metadata for `HeroListComponent`:
+makeExample('architecture/ts/app/hero-list.component.ts', 'metadata', 'app/hero-list.component.ts (metadata)')
TypeScript中附加元数据的简单方式是 **装饰器(decorator)** 。
下面就是`HeroListComponent`的一些元数据。
+makeExample('architecture/ts/app/hero-list.component.ts', 'metadata', 'app/hero-list.component.ts (元数据)')
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Here we see the `@Component` decorator which (no surprise) identifies the class Here we see the `@Component` decorator which (no surprise) identifies the class
immediately below it as a Component class. immediately below it as a Component class.
这里我们看到`@Component`装饰器(理所当然的)标记出紧跟着它的这个类是一个组件类。
A decorator is a function. Decorators often have a configuration parameter. A decorator is a function. Decorators often have a configuration parameter.
The `@Component` decorator takes a required configuration object with the The `@Component` decorator takes a required configuration object with the
information Angular needs to create and present the component and its view. information Angular needs to create and present the component and its view.
装饰器是一个函数。装饰器通常还有配置参数。
`@Component`装饰器可以带一个配置对象这些信息会被Angular用来创建和展示组件及其视图。
Here we see a few of the possible `@Component` configuration options: Here we see a few of the possible `@Component` configuration options:
* `selector` - a css selector that tells Angular to create and insert an instance of this component * `selector` - a css selector that tells Angular to create and insert an instance of this component