本文介绍了Ionic 2 - 从存储值获取令牌并在HTTP请求之前设置Header的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 29岁程序员，3月因学历无情被辞！ 我正在使用离子/存储程序包为用户登录后存储 api_token ，以便我可以使用唯一令牌与API进行交互。I am using the ionic/storage package to store the api_token for users after they logged in so I can use the unique token to interact with an API.我面临的问题是我需要通过 storage.get获取值返回一个promise并导致我想要设置的标题没有及时设置。The problem I am facing is that I need to get the value via storage.get which returns a promise and results in the headers I want to set not being set in time.我需要返回一个RequestOptions实例但是可以'弄清楚如何添加我从一个承诺来检索的标题。添加与localStorage同步的头文件在测试时工作正常，因此问题必须是异步执行。I need to return an instance of RequestOptions but can't figure out how to add the header I retrieve when it comes from a promise. Adding a header synchronous with localStorage is working fine when testing so the issue must be the asynch execution.createAuthorizationHeader(headers: Headers) { // this does add the header in time localStorage.setItem('api_token', 'some token'); headers.append('Authorization', 'Bearer ' + localStorage.getItem('api_token')); // this does not add the header in time return this.storage.get('api_token').then((value) => { headers.append('Authorization', 'Bearer ' + value); });}getHeaders(path): RequestOptions { let headers = new Headers({ 'Accept': 'application/json', 'Content-Type': 'application/json' }); if(!this.isGuestRoute(path)) { this.createAuthorizationHeader(headers); } return new RequestOptions({ headers: headers });}get(path: string) { return this._http.get(this.actionUrl + path, this.getHeaders(path)) .map(res => res.json()) .catch(this.handleError);} 编辑：工作代码现在看起来像这样getApiToken(): Observable<Headers> { return Observable.fromPromise(this.storage.get('api_token'));}getHeaders(): Headers { return new Headers({ 'Accept': 'application/json', 'Content-Type': 'application/json' });}get(path: string) { let headers: Headers = this.getHeaders(); if(!this.isGuestRoute(path)) { return this.getApiToken().flatMap(data => { headers.append('Authorization', 'Bearer' + data); return this._http.get(this.actionUrl + path, { headers : headers }) .map(res => res.json()) .catch(this.handleError); }); } return this._http.get(this.actionUrl + path, { headers : headers }) .map(res => res.json()) .catch(this.handleError);}推荐答案查看我的类似问题 Angular2 - 在另一个Observable中使用Observable返回方法的值如果将Promise转换为 Observable ，您将可以使用rxjs flatMap 功能。If you convert the Promise to a Observable you will be able to use the rxjs flatMap function.让我告诉你看起来有点像什么Let me show you what your would somewhat look like thengetApiToken(): Observable<Headers> { return Observable.fromPromise(this.storage.get('api_token')); //OR return Observalbe.of(this.storage.get('api_token'));}getHeaders(): Headers { //create all headers here except the 'api_token' .....}get(path: string): Observable<any> { let headers: Headers = this.getHeaders(); return this.getApiToken().flatMap(data => { headers.append('Authorization', 'Bearer'+data); return this.http.get(this.actionUrl + path, headers) .map(res => res.json()) .catch(this.handleError); });}或者（刚刚了解了这一点，所以不确定它是否可行）OR (Just learned about this so not sure if it will work)createAuthorizationHeader(headers: Headers) { // this does add the header in time localStorage.setItem('api_token', 'some token'); headers.append('Authorization', 'Bearer ' + localStorage.getItem('api_token')); // this does not add the header in time let api_token = await this.storage.get('api_token'); headers.append('Authorization', 'Bearer ' + api_token);} 这篇关于Ionic 2 - 从存储值获取令牌并在HTTP请求之前设置Header的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！
