angular - 为什么在 API 调用上使用 Angular 服务更好？

Question

当对后端进行 HTTP 调用或 API 调用时，Angular 服务做什么以及为什么使用它有好处？

Answer 1

如 Angular documentation 中所述，组件的用途如下:

Ideally, a component's job is to enable the user experience and nothing more. A component should present properties and methods for data binding, in order to mediate between the view (rendered by the template) and the application logic (which often includes some notion of a model).

在下一段中，解释了服务的目的:

A component can delegate certain tasks to services, such as fetching data from the server, validating user input, or logging directly to the console. By defining such processing tasks in an injectable service class, you make those tasks available to any component. You can also make your app more adaptable by injecting different providers of the same kind of service, as appropriate in different circumstances.

在软件工程术语中，这符合单例 模式。在 Angular 中，定义和创建服务的标准做法是在根级别提供它们，然后创建服务的共享实例，该实例可以注入(inject)到需要它的其他类/组件中。

在您的服务文件中，您可能会注意到 @Injectable() 装饰器，它可能看起来像这样:

@Injectable()
export class SampleService {

  // other things within your service

}

这将类表示为“服务”，它将告诉 Angular 将其作为依赖项注入(inject)到其他组件中。您可以通过 here 阅读更多关于依赖注入(inject)的信息。 .