在Angular 2中防止多次调用访问Token API

import { Injectable } from '@angular/core';
import { Subject } from 'rxjs';

@Injectable()
export class TokenService {
  private tokenSubject: Subject<string> = new Subject<string>();
  private token: string;

  constructor() { }

  getToken(): Observable<string> {
    if (this.token) {
      return of(this.token);
    } else {
      return this.tokenSubject.asObservable();
    }
  }

  setToken(token: string) {
    this.token = token;
    this.tokenSubject.next(token);
  }
}

import { Component, OnInit } from '@angular/core';
import { TokenService } from 'path/to/token.service';

@Component({
  selector: 'app-example',
  templateUrl: './example.component.html',
  styleUrls: ['./example.component.css']
})
export class ExampleComponent implements OnInit {
  token: string;

  constructor(private tokenService: TokenService) { }

  ngOnInit() {
    this.tokenService.getToken().subscribe(token => {
      this.token = token;
      // 在这里进行Token API的调用
      // ...
    });
  }
}

import { Component } from '@angular/core';
import { TokenService } from 'path/to/token.service';

@Component({
  selector: 'app-login',
  templateUrl: './login.component.html',
  styleUrls: ['./login.component.css']
})
export class LoginComponent {
  constructor(private tokenService: TokenService) { }

  login() {
    // 在这里进行登录操作，获取Token
    const token = 'your_token_here';
    this.tokenService.setToken(token);
  }
}