@Injectable()
export class AuthenticationService {
    public token: string;
    .......... your other codes.....................
    login(username: string, password: string): Observable<boolean> {
        return this.http.post('/api/authenticate', JSON.stringify({ username: username, password: password }))
            .map((response: Response) => {
                // login successful if there's a jwt token in the response
                let token = response.json() && response.json().token;
                if (token) {
                    // set token property
                    this.token = token;

                    // store username and jwt token
                    localStorage.setItem('usertoken', JSON.stringify({ username: username, token: token }));

                    // return true to indicate successful login
                    return true;
                } else {
                    // return false to indicate failed login
                    return false;
                }
            });
    }
 ....................... your other codes.......................
}

@Injectable()
export class UserService {
    constructor(
        private http: Http,
        private authenticationService: AuthenticationService) {
    }

    getUsers(): Observable<User[]> {
        // add authorization header with jwt token
        let headers = new Headers({ 'Authorization': 'Bearer ' + this.authenticationService.token });
        let options = new RequestOptions({ headers: headers });

        // get users from api
        return this.http.get('/api/users', options)
            .map((response: Response) => response.json());
    }
}