135 lines
5.4 KiB
Markdown
135 lines
5.4 KiB
Markdown
# Sharing Modules
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# 共享特性模块
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#### Prerequisites
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#### 前提条件
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A basic understanding of the following:
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对下列知识有基本的了解：
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* [Feature Modules](guide/feature-modules).
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[特性模块](guide/feature-modules).
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* [JavaScript Modules vs. NgModules](guide/ngmodule-vs-jsmodule).
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[JavaScript 模块与 NgModules](guide/ngmodule-vs-jsmodule)。
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* [Frequently Used Modules](guide/frequent-ngmodules).
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[常用模块](guide/frequent-ngmodules).
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* [Routing and Navigation](guide/router).
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[路由与导航](guide/router).
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* [Lazy loading modules](guide/lazy-loading-ngmodules).
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[惰性加载模块](guide/lazy-loading-ngmodules).
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<!--* Components (#TBD) We don’t have a page just on the concept of components, but I think one would be helpful for beginners.-->
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<hr>
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Creating shared modules allows you to organize and streamline your code. You can put commonly
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used directives, pipes, and components into one module and then import just that module wherever
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you need it in other parts of your app.
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创建共享模块能让你更好地组织和梳理代码。你可以把常用的指令、管道和组件放进一个模块中，然后在应用中其它需要这些的地方导入该模块。
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Consider the following module from an imaginary app:
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想象某个应用有下列模块：
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```typescript
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import { CommonModule } from '@angular/common';
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import { NgModule } from '@angular/core';
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import { FormsModule } from '@angular/forms';
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import { CustomerComponent } from './customer.component';
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import { NewItemDirective } from './new-item.directive';
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import { OrdersPipe } from './orders.pipe';
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@NgModule({
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imports: [ CommonModule ],
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declarations: [ CustomerComponent, NewItemDirective, OrdersPipe ],
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exports: [ CustomerComponent, NewItemDirective, OrdersPipe,
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CommonModule, FormsModule ]
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})
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export class SharedModule { }
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```
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Note the following:
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请注意以下几点：
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* It imports the `CommonModule` because the module's component needs common directives.
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它导入了 `CommonModule`，因为该模块需要一些常用指令。
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* It declares and exports the utility pipe, directive, and component classes.
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它声明并导出了一些工具性的管道、指令和组件类。
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* It re-exports the `CommonModule` and `FormsModule`.
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它重新导出了 `CommonModule` 和 `FormsModule`
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By re-exporting `CommonModule` and `FormsModule`, any other module that imports this
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`SharedModule`, gets access to directives like `NgIf` and `NgFor` from `CommonModule`
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and can bind to component properties with `[(ngModel)]`, a directive in the `FormsModule`.
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通过重新导出 `CommonModule` 和 `FormsModule`，任何导入了这个 `SharedModule` 的其它模块，就都可以访问来自 `CommonModule` 的 `NgIf` 和 `NgFor` 等指令了，也可以绑定到来自 `FormsModule` 中的 `[(ngModel)]` 的属性了。
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Even though the components declared by `SharedModule` might not bind
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with `[(ngModel)]` and there may be no need for `SharedModule`
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to import `FormsModule`, `SharedModule` can still export
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`FormsModule` without listing it among its `imports`. This
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way, you can give other modules access to `FormsModule` without
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having to import it directly into the `@NgModule` decorator.
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即使 `SharedModule` 中声明的组件没有绑定过 `[(ngModel)]`，而且`SharedModule` 也不需要导入 `FormsModule`，`SharedModule` 仍然可以导出 `FormsModule`，而不必把它列在 `imports` 中。
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这种方式下，你可以让其它模块也能访问 `FormsModule`，而不用直接在自己的 `@NgModule` 装饰器中导入它。
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### Using components vs services from other modules.
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### 使用来自其它模块的组件和服务
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There is an important distinction between using another module's component and
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using a service from another module. Import modules when you want to use
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directives, pipes, and components. Importing a module with services means that you will have a new instance of that service, which typically is not what you need (typically one wants to reuse an existing service). Use module imports to control service instantiation.
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在使用来自其它模块的组件和来自其它模块的服务时，有一个很重要的区别。
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当你要使用指令、管道和组件时，导入那些模块就可以了。而导入带有服务的模块意味着你会拥有那个服务的一个新实例，这通常不会是你想要的结果（你通常会想取到现存的服务）。使用模块导入来控制服务的实例化。
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The most common way to get a hold of shared services is through Angular
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[dependency injection](guide/dependency-injection), rather than through the module system (importing a module will result in a new service instance, which is not a typical usage).
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获取共享服务的最常见方式是通过 Angular 的[依赖注入系统](guide/dependency-injection)，而不是模块系统（导入模块将导致创建新的服务实例，那不是典型的用法）。
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To read about sharing services, see [Providers](guide/providers).
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要进一步了解共享服务，参见[服务提供商](guide/providers)。
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<hr />
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## More on NgModules
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## 关于 NgModule 的更多知识
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You may also be interested in the following:
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你可能还对下列内容感兴趣：
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* [Providers](guide/providers).
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[服务提供商](guide/providers).
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* [Types of Feature Modules](guide/module-types).
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[特性模块的分类](guide/module-types).
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