NgModule API
Prerequisites
前提条件
A basic understanding of the following concepts:
对下列概念有基本的理解:
Purpose of @NgModule
@NgModule
的设计意图
At a high level, NgModules are a way to organize Angular apps and they accomplish this through the metadata in the @NgModule
decorator. The metadata falls into three categories:
宏观来讲,NgModule 是组织 Angular 应用的一种方式,它们通过 @NgModule
装饰器中的元数据来实现这一点。 这些元数据可以分成三类:
Static: Compiler configuration which tells the compiler about directive selectors and where in templates the directives should be applied through selector matching. This is configured via the
declarations
array.静态的:编译器配置,用于告诉编译器指令的选择器并通过选择器匹配的方式决定要把该指令应用到模板中的什么位置。它是通过
declarations
数组来配置的。Runtime: Injector configuration via the
providers
array.运行时:通过
providers
数组提供给注入器的配置。Composability/Grouping: Bringing NgModules together and making them available via the
imports
andexports
arrays.
@NgModule
metadata
@NgModule
元数据
The following table summarizes the @NgModule
metadata properties.
下面是 @NgModule
元数据中属性的汇总表:
Property 属性 | Description 说明 |
---|---|
A list of declarable classes, (components, directives, and pipes) that belong to this module. 属于该模块的可声明对象(组件、指令和管道)的列表。
Components, directives, and pipes must belong to exactly one module. The compiler emits an error if you try to declare the same class in more than one module. Be careful not to re-declare a class that is imported directly or indirectly from another module. 组件、指令和管道只能属于一个模块。 如果尝试把同一个类声明在多个模块中,编译器就会报告一个错误。 小心,不要重复声明从其它模块中直接或间接导入的类。 | |
| A list of dependency-injection providers. 依赖注入提供商的列表。 Angular registers these providers with the NgModule's injector. If it is the NgModule used for bootstrapping then it is the root injector. Angular 会使用该模块的注入器注册这些提供商。 如果该模块是启动模块,那就会使用根注入器。 These services become available for injection into any component, directive, pipe or service which is a child of this injector. 当需要注入到任何组件、指令、管道或服务时,这些服务对于本注入器的子注入器都是可用的。 A lazy-loaded module has its own injector which is typically a child of the application root injector. 惰性加载模块有自己的注入器,它通常是应用的根注入器的子注入器。 Lazy-loaded services are scoped to the lazy module's injector. If a lazy-loaded module also provides the 惰性加载的服务是局限于这个惰性加载模块的注入器中的。 如果惰性加载模块也提供了 Components in external modules continue to receive the instance provided by their injectors. 其它外部模块中的组件也会使用它们自己的注入器提供的服务实例。 For more information on injector hierarchy and scoping, see Providers and the DI Guide. 要深入了解关于多级注入器及其作用域,参见服务提供商。 |
A list of modules which should be folded into this module. Folded means it is as if all the imported NgModule's exported properties were declared here. 要折叠(Folded)进本模块中的其它模块。折叠的意思是从被导入的模块中导出的那些软件资产同样会被声明在这里。 Specifically, it is as if the list of modules whose exported components, directives, or pipes are referenced by the component templates were declared in this module. 特别是,这里列出的模块,其导出的组件、指令或管道,当在组件模板中被引用时,和本模块自己声明的那些是等价的。 A component template can reference another component, directive, or pipe when the reference is declared in this module or if the imported module has exported it. For example, a component can use the 组件模板可以引用其它组件、指令或管道,不管它们是在本模块中声明的,还是从导入的模块中导出的。 比如,只有当该模块导入了 Angular 的 You can import many standard directives from the 你可以从 | |
A list of declarations—component, directive, and pipe classes—that an importing module can use. 可供导入了自己的模块使用的可声明对象(组件、指令、管道类)的列表。 Exported declarations are the module's public API. A component in another module can use this module's 导出的可声明对象就是本模块的公共 API。 只有当其它模块导入了本模块,并且本模块导出了 Declarations are private by default. If this module does not export 默认情况下这些可声明对象都是私有的。 如果本模块没有导出 Importing a module does not automatically re-export the imported module's imports. Module 'B' can't use 导入某个模块并不会自动重新导出被导入模块的那些导入。 模块 B 不会因为它导入了模块 A,而模块 A 导入了 A module can list another module among its 一个模块可以把另一个模块加入自己的 Re-export makes module transitivity explicit. If Module 'A' re-exports 重新导出可以让模块被显式传递。 如果模块 A 重新导出了 | |
A list of components that are automatically bootstrapped. 要自动启动的组件列表。 Usually there's only one component in this list, the root component of the application. 通常,在这个列表中只有一个组件,也就是应用的根组件。 Angular can launch with multiple bootstrap components, each with its own location in the host web page. Angular 也可以引导多个引导组件,它们每一个都在宿主页面中有自己的位置。 A bootstrap component is automatically added to 启动组件会自动添加到 | |
| A list of components that can be dynamically loaded into the view. 那些可以动态加载进视图的组件列表。 By default, an Angular app always has at least one entry component, the root component, 默认情况下,Angular 应用至少有一个入口组件,也就是根组件 Routed components are also entry components because they need to be loaded dynamically. The router creates them and drops them into the DOM near a 路由组件也是入口组件,因为你需要动态加载它们。 路由器创建它们,并把它们扔到 DOM 中的 While the bootstrapped and routed components are entry components, you don't have to add them to a module's 虽然引导组件和路由组件都是入口组件,不过你不用自己把它们加到模块的 Angular automatically adds components in the module's Angular 会自动把模块的 That leaves only components bootstrapped using one of the imperative techniques, such as 而那些使用不易察觉的 Dynamic component loading is not common in most apps beyond the router. If you need to dynamically load components, you must add these components to the 动态组件加载在除路由器之外的大多数应用中都不太常见。如果你需要动态加载组件,就必须自己把那些组件添加到 For more information, see Entry Components. 要了解更多,参见入口组件一章。 |
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关于 NgModule 的更多知识
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