Angular 4 http CORS No "Access-Control-Allow-Origin" with Java Servlet
I am trying to do http.post but chrome shows the following error:
No Access-Control-Allow-Origin.
My Angular function:
onSubmit(event: Event) {
event.preventDefault();
this.leerDatos()
.subscribe(res => {
//datos = res.json();
console.log("Data send");
}, error => {
console.log(error.json());
});
}
leerDatos(): Observable<any> {
let headers = new Headers({ 'Content-Type': 'application/json' });
let options = new RequestOptions({ headers: headers });
return this.http.post(`http://localhost:8080/LegoRepositoryVincle/CoreServlet`, { name: "bob" }, options)
//.map(this.extractData)
//.catch(this.handleError);
}
And my doPost method of my servlet includes:
response.setContentType("application/json");
response.setCharacterEncoding("utf-8");
response.addHeader("Access-Control-Allow-Origin","http://localhost:4200");
response.addHeader("Access-Control-Allow-Credentials", "true");
response.addHeader("Access-Control-Allow-Methods","GET,POST");
response.addHeader("Access-Control-Allow-Headers","X-PINGOTHER, Origin, X-Requested-With, Content-Type, Accept, Cache-Control, Pragma");
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If you still want to use CORS when developing, you can solve this problem using angular / cli --proxy-config .
Essentially if you want to make requests to a remote machine, for example on an nginx webserver, you execute all your calls to the same application, for example localhost:4200
(by default in angular / cli). Then you redirect those responses to your server with --proxy-config
.
Suppose you have all prefix entry points in your api server /api
. You need to create a file called proxy.config.json in your project root directory and configure it like this:
{
"/api" : {
"target" : "http://xx.xxx.xxx.xx", // Your remote address
"secure" : false,
"logLevel" : "debug", // Making Debug Logs in console
"changeOrigin": true
}
}
And then all your HTTP requests will point to localhost:4200/api/
.
Finally, you must do by executing ng server --proxy-config proxy.config.json
.
If you notice that some headers are missing from the request, add them from your web server or edit http.service.ts
to add the ones shown in this example:
import { Injectable } from '@angular/core';
import { Http, Headers, RequestOptions } from '@angular/http';
import { Observable } from 'rxjs/Rx';
import { isNull } from 'lodash';
@Injectable()
export class HttpClientService {
private _host: string;
private _authToken: string;
private _options: RequestOptions = null;
constructor(private _http: Http, private _config: AppConfig, private _localStorageService: LocalStorageService) {
this._host = ''; // Your Host here, get it from a configuration file
this._authToken = ''; // Your token here, get it from API
}
/**
* @returns {RequestOptions}
*/
createAuthorizationHeader(): RequestOptions {
// Just checking is this._options is null using lodash
if (isNull(this._options)) {
const headers = new Headers();
headers.append('Content-Type', 'application/json; charset=utf-8');
headers.append('Authorization', this._authToken);
this._options = new RequestOptions({headers: headers});
}
return this._options;
}
/**
* @param url {string}
* @param data {Object}
* @return {Observable<any>}
*/
get(url?: string, data?: Object): Observable<any> {
const options = this.createAuthorizationHeader();
return this._http.get(this._host + url, options);
}
/**
* @param url {string}
* @param data {Object}
* @return {Observable<any>}
*/
post(url?: string, data?: Object): Observable<any> {
const body = JSON.stringify(data);
const options = this.createAuthorizationHeader();
return this._http.post(this._host + url, body, options);
}
}
So you will be making all your api calls through this service, for example
import { Component, OnInit } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import { HttpClientService } from './http.service.ts';
export class TestComponent implements OnInit {
_observable: Observable<any> = null;
constructor(private _http: HttpClientService) { }
ngOnInit() {
this._observable = this _http.get('test/')
.map((response: Response) => console.log(response.json()));
}
}
Angular 5 Update :
In app.module.ts
now you need to replace import { HttpModule } from '@angular/http';
with import { HttpClientModule } from '@angular/common/http';
.
The service will change slightly to:
import { Injectable } from '@angular/core';
import { HttpClient, HttpHeaders } from '@angular/common/http';
import { isNull, isUndefined } from 'lodash';
@Injectable()
export class HttpClientService {
private _host: string;
private _authToken: string;
private __headers: HttpHeaders;
constructor(private _http: HttpClient, private _config: AppConfig, private _localStorageService: LocalStorageService) {
this._host = ''; // Your Host here, get it from a configuration file
this._authToken = ''; // Your token here, get it from API
}
/**
* @returns {HttpHeaders}
*/
createAuthorizationHeader(): HttpHeaders {
// Just checking is this._options is null using lodash
if (isNull(this.__headers)) {
const headers = new HttpHeaders()
.set('Content-Type', 'application/json; charset=utf-8')
.set('Authorization', this. _authToken || '');
this.__headers= new RequestOptions({headers: headers});
}
return this.__headers;
}
/**
* @param url {string}
* @param data {Object}
* @return {Observable<any>}
*/
get(url?: string, data?: Object): Observable<any> {
const options = this.createAuthorizationHeader();
return this._http.get(this._host + url, {
headers : this.createAuthorizationHeader()
});
}
/**
* @param url {string}
* @param data {Object}
* @return {Observable<any>}
*/
post(url?: string, data?: Object): Observable<any> {
const body = JSON.stringify(data);
const options = this.createAuthorizationHeader();
return this._http.post(this._host + url, body, {
headers : this.createAuthorizationHeader()
});
}
}
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