Angular2-对预检请求的响应未通过访问控制检查:请求的资源上没有"Access-Control-Allow-Origin"标头

Question

我在Angular 2中调用了一个http帖子.这在post man中工作得很好但是当我在Angular 2中实现这个API调用时,我得到No'Access-Control-Allow'错误.这是我的代码

getInspections(): Observable<IInspection[]> {
        if (!this.inspections) {
            let body =JSON.stringify({"Statuses":["Submitted", "Opened"]});
            let headers = new Headers({ 'Content-Type': 'application/json' });

            headers.append('Access-Control-Allow-Origin','*');
            let options = new RequestOptions({ headers: headers });

            return this.http.post(this._baseUrl + '/api/Inspect/ListI',body,options)
                .map((res: Response) => {
                    this.inspections = res.json();
                    return this.inspections;
                })
                .catch(this.handleError);
        }
        else {
            //return cached data
            return this.createObservable(this.inspections);
        }
    }

或者我可以这样做吗？只需传递标题而不是选项

getInspections(): Observable<IInspection[]> {
        if (!this.inspections) {
            let body =JSON.stringify({"Statuses":["Submitted", "Opened"]});
            let headers = new Headers({ 'Content-Type': 'application/json' });

            //headers.append('Access-Control-Allow-Origin','*');
          //  let options = new RequestOptions({ headers:headers });

            return this.http.post(this._baseUrl + '/api/Inspect/ListI',body,headers)
                .map((res: Response) => {
                    this.inspections = res.json();
                    return this.inspections;
                })
                .catch(this.handleError);
        }
        else {
            //return cached data
            return this.createObservable(this.inspections);
        }
    }

Answer 1

CORS标题就像

headers.append('Access-Control-Allow-Origin','*');

需要由服务器提供.在客户端添加它们毫无意义.