共享特性模块link

Sharing moduleslink

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。

Creating shared modules allows you to organize and streamline your code. You can put commonly used directives, pipes, and components into one module and then import just that module wherever you need it in other parts of your app.

想象某个应用有下列模块：

Consider the following module from an imaginary app:

      
        content_copy
      
      import { CommonModule } from '@angular/common';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { CustomerComponent } from './customer.component';
import { NewItemDirective } from './new-item.directive';
import { OrdersPipe } from './orders.pipe';

@NgModule({
 imports:      [ CommonModule ],
 declarations: [ CustomerComponent, NewItemDirective, OrdersPipe ],
 exports:      [ CustomerComponent, NewItemDirective, OrdersPipe,
                 CommonModule, FormsModule ]
})
export class SharedModule { }
    

请注意以下几点：

Note the following:

• 它导入了 CommonModule，因为该模块需要一些常用指令。

  It imports the CommonModule because the module's component needs common directives.

• 它声明并导出了一些工具性的管道、指令和组件类。

  It declares and exports the utility pipe, directive, and component classes.

• 它重新导出了 CommonModule 和 FormsModule

  It re-exports the CommonModule and FormsModule.

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。

By re-exporting CommonModule and FormsModule, any other module that imports this SharedModule, gets access to directives like NgIf and NgFor from CommonModule and can bind to component properties with [(ngModel)], a directive in the FormsModule.

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。 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。

Even though the components declared by SharedModule might not bind with [(ngModel)] and there may be no need for SharedModule to import FormsModule, SharedModule can still export FormsModule without listing it among its imports. This way, you can give other modules access to FormsModule without having to import it directly into the @NgModule decorator.

关于 NgModule 的更多知识link

More on NgModuleslink

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• 服务提供者。

  Providers.

• 特性模块的分类。

  Types of Feature Modules.