Angular 4 Post Method
obtainAccessToken(loginData){
let params = new URLSearchParams();
params.append('username',loginData.username);
params.append('password',loginData.password);
params.append('grant_type','password');
params.append('client_id','fooClientIdPassword');
let headers = new Headers({'Content-type': 'application/x-www-form-urlencoded; charset=utf-8', 'Authorization': 'Basic '+btoa("fooClientIdPassword:secret")});
let options = new RequestOptions({ headers: headers });
this._http.post('http://localhost:8081/spring-security-oauth-server/oauth/token', params.toString(), options)
.map(res => res.json())
.subscribe(
data => this.saveToken(data),
err => alert('Invalid Credentials'));
}