ionic3+ angular4.0.x 開發雲小客 會員端之 http 接口監控，實現token管理登陸。

功能， 自動在http請求時添加token, 若token過時或者沒有附帶token, 根據後臺返回狀態401,500，直接跳轉到登陸界面。

import { Events, NavController, NavParams ,App } from 'ionic-angular';
import { Injectable, Injector } from '@angular/core';
import 'rxjs';
import {Http, RequestOptionsArgs, Response, RequestOptions, ConnectionBackend, Headers} from '@angular/http';
import {Observable} from 'rxjs/Observable';
import {Storage} from '@ionic/storage';
import 'rxjs/add/operator/toPromise';
import 'rxjs/add/operator/map';
import { Login } from '../../pages/login/login';

@Injectable()
export class HttpInterceptor extends Http {

  private navCtrl: NavController;

  constructor(connectionBackend: ConnectionBackend, 
    requestOptions: RequestOptions, 
    app: App,
    public storage: Storage) {
    super(connectionBackend, requestOptions);
    this.navCtrl = app.getActiveNav();
  }

  public get(url: string, options?: RequestOptionsArgs): Observable<Response> {
    return Observable.fromPromise(
      this.getRequestOptionArgs(options)
    ).mergeMap((options) => {
      return super.get(url, options)
    });
  }

  private goTo(url: string) {
    console.info('url: '+ url);
    // setTimeout(() => this.router.navigateByUrl(url));
  }

  public post(url: string, body: string, options?: RequestOptionsArgs): Observable<Response> {
    return Observable.fromPromise(
      this.getRequestOptionArgs(options)
    ).mergeMap((options) => {
      return super.post(url, body, options)
      .toPromise()
      .then(res => this.handleSuccess(res))
      .catch(res => this.handleError(res))
    })
  }

  public handleSuccess(res: Response) {
    return res;
  }

  public handleError(res: Response) {
    console.info(res);
    if (res.status == 401) {
      console.info(res);
    }
    switch (res.status) {
      case 200:
          break;
      case 401: // 未登陸狀態碼
        this.navCtrl.setRoot(Login);
        break;
      case 403:
      case 404:
      case 500:
          this.navCtrl.setRoot(Login);
          break;
    }

    return res;
  }

  public put(url: string, body: string, options?: RequestOptionsArgs): Observable<Response> {
    return Observable.fromPromise(
      this.getRequestOptionArgs(options)
    ).mergeMap((options) => {
      return super.put(url, body, options)
    })
  }

  public delete(url: string, options?: RequestOptionsArgs): Observable<Response> {
    return Observable.fromPromise(
      this.getRequestOptionArgs(options)
    ).mergeMap((options) => {
      return super.delete(url, options)
    });
  }

  private getRequestOptionArgs(options?: RequestOptionsArgs) {
    return this.storage.get('token').then((token) => {
      if (options == null) {
        options = new RequestOptions();
      }

      if (options.headers == null) {
        options.headers = new Headers();
      }

      // options.headers.append('Content-Type', 'application/json');
      if (options.headers.get("token") == null) {
        // options.headers.append('token','4CA05F76D6954EE39C45D2BD872542665A08252C0DD2953B279DD45C75664449BCAA5B062FF9B4C8D8747A112EC455306EFC21085AED34E4675C4E0D996EF6105DFA912601EFE111');
        if (token !== null) {
          options.headers.append('token', token);
        }
  
      }
      return options;
    });
  }
}