Angular7 HttpClient处理多个请求

import {HttpClient} from ‘@angular/common/http‘;
import {mergeMap} from ‘rxjs‘;

@Component({
   ...
})
export class HttpComponent implements OnInit {


  constructor(private http: HttpClient) { }


  ngOnInit() {
    // 串联请求, 前面请求会影响后面的请求，前面请求未请求到，后面请求中断；
    const httpThis = this;
    httpThis.http.get(‘/api/token‘).
      pipe(
      map(token => {
        return token;
      }),
      mergeMap((tokenRes: any) => { // tokenRes接收的是token数据
        return httpThis.http.get(`/api/user?token=${tokenRes}`)
          .pipe((user) => {
            return user;
          });
      }),
      mergeMap((userRes: any) => { // userRes接收的是user数据
        return httpThis.http.get(`api/data?user=${userRes}`)
          .pipe((data) => {
            return data;
          });
      }))
      .subscribe((resp) => { // resp接收的是data数据
        console.log(‘最终结果resp是最后一个mergeMap的data‘);
      });
  }
}

import {HttpClient} from ‘@angular/common/http‘;
import {forkJoin} from ‘rxjs‘;

@Component({
   ...
})


export class HttpComponent implements OnInit {


  constructor(private http: HttpClient) { }


  ngOnInit() {
     
    // 并联请求
    const post1 = this.requestData1();
    const post2 = this.requestData2();
    forkJoin([post1, post2])
      .subscribe((data: any) => {
        const postResult1 = data[0]; // ‘/api/post1的返回结果‘
        const postResult2 = data[1]; // ‘/api/post2的返回结果‘
      });
  }


  // 并联请求1
  requestData1() {
    return this.http.get(‘/api/post1‘)
      .pipe((data) => {
        return data;
      });
  }


  // 并联请求2
  requestData2() {
    return this.http.get(‘/api/post2‘)
      .pipe((data) => {
        return data;
      });
  }
}