package org.xmlhammer.gui.util;

 import java.awt.Frame;

 import javax.swing.JOptionPane;

 import javax.swing.SwingUtilities;

 import org.apache.log4j.AppenderSkeleton;

 import org.apache.log4j.Level;

 import org.apache.log4j.spi.LoggingEvent;

 public class UIAppender extends AppenderSkeleton {

     private Frame frame = null;

     public UIAppender( Frame frame) {

         super();

         this.frame = frame;

     }

     @Override

     protected void append(LoggingEvent event) {

         if (event.getLevel() == Level.ERROR) {

             if ( event.getThrowableInformation() != null && event.getThrowableInformation().getThrowable() != null) {

                 Throwable t = event.getThrowableInformation().getThrowable();

                 while (t.getCause() != null) {

                     t = t.getCause();

                 }

                 StringBuffer message = new StringBuffer();

                 if (t.getMessage() == null || t.getMessage().length() == 0) {

                     message.append(t.getClass().toString());

                     message.append("\nPlease see log for more information.");

                 } else {

                     message.append(t.getMessage());

                     message.append("\nPlease see log for more information.");

                 }

                 showMessage(frame, message.toString(), event.getRenderedMessage());

             } else {

                 showMessage(frame, event.getRenderedMessage(), "Module Error");

             }

         }

     }

     private void showMessage(final Frame frame, final String message, final String title) {

         if (SwingUtilities.isEventDispatchThread()) {

             JOptionPane.showMessageDialog( frame, message, title, JOptionPane.ERROR_MESSAGE);

         } else {

             SwingUtilities.invokeLater(new Runnable() {

                 public void run() {

                     JOptionPane.showMessageDialog( frame, message, title, JOptionPane.ERROR_MESSAGE);

                 }

             });

         }

     }

     @Override

     public boolean requiresLayout() {

         return false;

     }

     @Override

     public void close() {

     }

 }