如何在Angular2中创建拦截器?

问题描述

我正在Angular2中构建我的第一个更大的应用程序，我想知道如何构建可以替代Angular1拦截器的东西?我正在研究Internet，发现可以创建一个类，该类与Http类几乎相同.但是，我不知道如何实现我最感兴趣的两个功能:拦截请求中的错误，向所有请求添加标头.

I am building my first larger app in Angular2, and I am wondering how can I build something which will be an alternative to Angular1 interceptors? I was digging the Internet, and found out that I can create a class, which will be pretty much the same as Http class. However, I have no idea how I can implement two functionalities that I am the most interested in: intercepting errors from request, adding a header to all of the request.

欢迎任何指针！

推荐答案

您可以创建一个扩展Http的类:

You could create a class that extends the Http:

@Injectable()
export class CustomHttp extends Http {
  constructor(backend: ConnectionBackend, defaultOptions: RequestOptions) {
    super(backend, defaultOptions);
  }

  request(url: string | Request, options?: RequestOptionsArgs): Observable<Response> {
    console.log('request...');
    return super.request(url, options).catch(res => {
      // do something
    });        
  }

  get(url: string, options?: RequestOptionsArgs): Observable<Response> {
    console.log('get...');
    return super.get(url, options).catch(res => {
      // do something
    });
  }
}

并按如下所述进行注册:

and register it as described below:

bootstrap(AppComponent, [HTTP_PROVIDERS,
    new Provider(Http, {
      useFactory: (backend: XHRBackend, defaultOptions: RequestOptions) => new CustomHttp(backend, defaultOptions),
      deps: [XHRBackend, RequestOptions]
  })
]);

这样，您将能够拦截请求...

This way you will be able to intercept requests...

针对RC4的更新

bootstrap(AppComponent, [HTTP_PROVIDERS,
    { provide: Http,
      useFactory: (backend: XHRBackend, defaultOptions: RequestOptions) => new CustomHttp(backend, defaultOptions),
      deps: [XHRBackend, RequestOptions]
    }
]);

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