角度4.3拦截器-如何使用?

这个答案是借用了 official documentation

Angular允许您创建HttpInterceptor:

import {Injectable} from '@angular/core';
import {HttpEvent, HttpInterceptor, HttpHandler, HttpRequest} from '@angular/common/http';

@Injectable()
export class NoopInterceptor implements HttpInterceptor {
  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    return next.handle(req);
  }
}

然后你可以像这样将其集成到你的应用程序中:

import {NgModule} from '@angular/core';
import {HTTP_INTERCEPTORS} from '@angular/common/http';

@NgModule({
  providers: [{
    provide: HTTP_INTERCEPTORS,
    useClass: NoopInterceptor,
    multi: true,
  }],
})
export class AppModule {}

要添加授权标头,可以使用更改的标头克隆请求:

import {Injectable} from '@angular/core';
import {HttpEvent, HttpInterceptor, HttpHandler, HttpRequest} from '@angular/common/http';

@Injectable()
export class AuthInterceptor implements HttpInterceptor {
  constructor(private auth: AuthService) {}

  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    // Get the auth header from the service.
    const authHeader = this.auth.getAuthorizationHeader();
    // Clone the request to add the new header.
    const authReq = req.clone({headers: req.headers.set('Authorization', authHeader)});
    // Pass on the cloned request instead of the original request.
    return next.handle(authReq);
  }
}

注意,拦截器就像一个链,因此可以设置多个拦截器来执行不同的任务。

附属国!InjectionToken\u HTTP\u拦截器(“[错误->]”):在里面 NgModule AppModule in/AppModule@-1:-1

Injector 属于 @angular/core localStorage 并使用basic auth。我需要设置

Authorization: 'Bearer token_string'

以下是我如何实现的:

令牌.interceptor.ts

import {Injectable, Injector} from '@angular/core';

import { HttpRequest, HttpHandler, HttpEvent, HttpInterceptor } from '@angular/common/http';
import {Observable} from 'rxjs/Observable';
import {AuthService} from './auth.service';

@Injectable()
export class TokenInterceptor implements HttpInterceptor {

    constructor(private injector: Injector) { }

    intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {

        const auth = this.injector.get(AuthService);
        if (auth.getToken()) {
            request = request.clone({
                setHeaders: {
                    Authorization: `Bearer ${auth.getToken()}`
                }
            });

        }

        return next.handle(request);
    }
}

AuthService中的getToken函数

在这里,您可以实现整个逻辑来获取报头或仅获取令牌。在我的例子中,我调用它只是为了获得JWT令牌字符串。

/**
 * Get jwt token
 * @returns {string}
 */
getToken(): string {
    return localStorage.getItem('token');
}

导入 TokenInterceptor

import {TokenInterceptor} from './pathToTheFile/token.interceptor';

@NgModule 在里面 providers:

providers: [
    {
        provide: HTTP_INTERCEPTORS,
        useClass: TokenInterceptor,
        multi: true
    }
    //, other providers
]

我选择实现一个拦截器和一系列可以在运行时扩展的处理函数。服务的intercept方法负责next()逻辑。

服务(基本代码,无验证或维护):

export type HttpHandlerFunction = (req: HttpRequest<any>) => HttpRequest<any>;

@Injectable()
export class HttpInterceptorService implements HttpInterceptor {
    private _handlers: Array<HttpHandlerFunction> = [];

    addHandler(handler: HttpHandlerFunction): void {
        this._handlers.push(handler);
    }

    intercept(req: HttpRequest<any>, next: HttpHandler):
        Observable<HttpEvent<any>> {
            this._handlers.forEach((handler: HttpHandlerFunction) => {
                req = handler(req);
            })
        return next.handle(req);
    }
}

以及在不同模块的某些服务中的用法:

constructor(injector: Injector) {

    const interceptorsArray: Array<any> = injector.get(HTTP_INTERCEPTORS),
        interceptor: HttpInterceptorService = interceptorsArray &&
            interceptorsArray.filter((i: any) => i instanceof HttpInterceptorService)[0];
    if (interceptor) {
        interceptor.addHandler((req: HttpRequest<any>) => {
            const accessToken = this.getAccessToken();
            if (accessToken) {
                // doesn't work with direct headers.set, you must clone
                req = req.clone({ headers: req.headers.set('Authorization', accessToken) });
            }
        return req;
    });
}