MyDefaultRequestTransport.java

package com.img.client.util;

import com.google.gwt.http.client.Request;
import com.google.gwt.http.client.RequestCallback;
import com.google.gwt.http.client.Response;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.inject.Inject;
import com.google.web.bindery.requestfactory.gwt.client.DefaultRequestTransport;
import com.google.web.bindery.requestfactory.shared.ServerFailure;
import com.sencha.gxt.core.client.Style;
import com.sencha.gxt.core.client.Style.AnchorAlignment;

//http://stackoverflow.com/questions/7608235/intercepting-gwt-requestfactory-requests
public class MyDefaultRequestTransport extends DefaultRequestTransport {
  
	@Inject
	private BusyIndicator indicator;
	
	@Override
    public void send(final String payload, final TransportReceiver receiver) {
        onIn();
        final TransportReceiver proxy = new TransportReceiver() {
            public void onTransportFailure(final ServerFailure failure) {
                onOut();
                receiver.onTransportFailure(failure);
            }

            public void onTransportSuccess(final String payload) {
            	onOut();
                receiver.onTransportSuccess(payload);
            }
        };

        super.send(payload, proxy);
	}
	
	private void onOut() {
		indicator.hide();	    
	}
	
	private void onIn() {	
	    //muestra gif
	    indicator.show(RootPanel.get().getElement(), new AnchorAlignment(Style.Anchor.TOP_LEFT, Style.Anchor.TOP_LEFT));	    
	}
	
	//http://stackoverflow.com/questions/6508238/gwt-authentication-for-some-part-of-application-using-gwt-login-page
	@Override
	  protected RequestCallback createRequestCallback(
	      final TransportReceiver receiver) {
	    final RequestCallback superCallback = super.createRequestCallback(receiver);

	    return new RequestCallback() {
	      public void onResponseReceived(Request request, Response response) {
	        /*
	         * The HTTPStatusCodeAuthenticationFilter filter responds with Response.SC_UNAUTHORIZED 
	         * if the user is not logged in. 
	         */
	        if (Response.SC_UNAUTHORIZED == response.getStatusCode()) {
	            /*
	             * Hand the receiver a non-fatal callback, so that
	             * com.google.web.bindery.requestfactory.shared.Receiver will not post a
	             * runtime exception.
	             */
	            receiver.onTransportFailure(new ServerFailure(
	                "Unauthenticated user", null, null, false /* not fatal */));
	            Window.Location.reload();
	            return;
	        }
	        superCallback.onResponseReceived(request, response);
	      }

	      public void onError(Request request, Throwable exception) {
	        superCallback.onError(request, exception);
	      }
	    };
	  }
}