Angular – Set headers for every request

I need to set some Authorization headers after the user has logged in, for every subsequent request.

To set headers for a particular request,

import {Headers} from 'angular2/http';
var headers = new Headers();
headers.append(headerName, value);

// HTTP POST using these headers
this.http.post(url, data, {
  headers: headers
})
// do something with the response

Reference

But it would be not be feasible to manually set request headers for every request in this way.

How do I set the headers set once the user has logged in, and also remove those headers on logout?