How to set headers to the content type application/json in Angular 2?

I'm trying to send HTTP post request in Angular 2, but I'm not able to set headers to the content type application/json.

My code is:

login(url,postdata)
{
    var headers = new Headers({'Content-Type': 'application/json'});
    return this._http.post(url,JSON.stringify(postdata),this.headers)
    .map(res => res.json())    
}

When I checked in network, I found that Content-Type is set as text/plain, and thus the server is not receiving any data.

Any suggestions will be appreciated.

Try this code:

private _getHeaders():Headers {
   let header = new Headers({
     'Content-Type': 'application/json'
   });

   return header;
}



public login(url, postdata){
   let options = new RequestOptions({
      headers: this._getHeaders()
   });
   return this.http.post(url, JSON.stringify(postdata),options).map(res => res.json());
}