我正在尝试使用Angular5实现HttpInterceptor在所有HTTP请求中注入Authorization标头。
我依赖于第三方库（ADAL，在此称为AuthService），该库提供了一种acquireToken()方法来获取用于持证人授权的令牌。
问题是aquireToken()返回一个可观察的值，我必须订阅才能获得我需要的真实字符串。
因此，我想我的代码永远不会注入标头，因为next.handle()在acquireToken()返回任何值之前先执行。
如何确保仅在获取令牌后才调用下一个处理程序？
import { Injectable, Injector } from '@angular/core';
import { HttpEvent, HttpInterceptor, HttpHandler, HttpRequest, HttpHeaders } from '@angular/common/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';
import {AuthService} from 'mylibrary';
@Injectable()
export class MyInterceptor implements HttpInterceptor {
constructor(private auth: AuthService) { }
intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
let headers = req.headers || new HttpHeaders();
this.auth.acquireToken(req.url)
.subscribe((token: string) => {
headers = headers.append('Authorization', 'Bearer ' + token);
});
return next.handle(req.clone({ headers: headers }));
}
}
这段代码将完成工作，技巧是使用 mergeMap
import { Injectable, Injector } from '@angular/core';
import { HttpEvent, HttpInterceptor, HttpHandler, HttpRequest, HttpHeaders } from '@angular/common/http';
import { Observable } from 'rxjs/Observable';
import { AdalService } from './adal.service';
import 'rxjs/add/operator/mergeMap';
@Injectable()
export class AdalInterceptor implements HttpInterceptor {
constructor(private adal: AdalService) { }
intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
// if the endpoint is not registered then pass
// the request as it is to the next handler
const resource = this.adal.GetResourceForEndpoint(req.url);
if (!resource) {
return next.handle(req.clone());
}
// if the endpoint is registered then acquire and inject token
let headers = req.headers || new HttpHeaders();
return this.adal.acquireToken(resource)
.mergeMap((token: string) => {
// if the user is not authenticated then drop the request
if (!this.adal.userInfo.authenticated) {
throw new Error('Cannot send request to registered endpoint if the user is not authenticated.');
}
// inject the header
headers = headers.append('Authorization', 'Bearer ' + token);
return next.handle(req.clone({ headers: headers }));
}
);
}
}
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