- @Injectable() export class ConstantService {


     constructor(private router: Router, private _logger: Logger) {   }

     public WEBSERVICE_URL: string = "http://localhost:8081/abcd/";

     public OAUTH2_CLIENT_USERNAME: string =
   "springbootproj-trusted-client";   public OAUTH2_CLIENT_PASSWORD:
   string = "secret";

     public MESSAGE_ACCESSTOKEN_EXPIRED: string = "Looks like your
   access token has been expired. Please login.";   public
   MESSAGE_INTERNAL_SERVER_ERROR: string = "Some internal server error
   has occured. Please try again. If problem persists then please
   contact Administrator.";   public MESSAGE_NO_RECORDFOUND_ERROR:
   string = "No records found.";

     public handleError = function (error: Response) {
       let errMsg = error.json().error || 'Server error';
       this._logger.error("Error",errMsg);
       // console.error("Response error: " + errMsg);

       if (error.status === 0) {
         alert(this.MESSAGE_ACCESSTOKEN_EXPIRED);
         this.router.navigate(['/login']);
       } else if (error.status === 500) {
         alert(this.MESSAGE_INTERNAL_SERVER_ERROR);
       }
       return Observable.throw(error.json().error || 'Server error');   }.bind(this);

     public extractData = function (res: Response) {
       if (res.status === 204) {
         alert(this.MESSAGE_NO_RECORDFOUND_ERROR);
       } else {
         let body: any;
         if (res.text()) {
           body = res.json();
         }
         return body || {};
       }   }.bind(this) }