com.github.apetrelli.gwtintegration.error.client.BaseUncaughtExceptionHandler Maven / Gradle / Ivy

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Better error and exception management under GWT

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package com.github.apetrelli.gwtintegration.error.client;

import java.util.logging.Level;
import java.util.logging.Logger;

import com.google.gwt.core.client.GWT;
import com.google.gwt.core.client.GWT.UncaughtExceptionHandler;
import com.google.web.bindery.event.shared.UmbrellaException;

/**
 * Handles client exceptions by showing an error message.
 */
public abstract class BaseUncaughtExceptionHandler implements UncaughtExceptionHandler {
	
	private Logger logger = Logger.getLogger(getClass().getName());

	/**
	 * Constructor.
	 */
	public BaseUncaughtExceptionHandler() {
	}

	@Override
	public void onUncaughtException(Throwable e) {
		// Get rid of UmbrellaException
		Throwable exceptionToDisplay = getExceptionToDisplay(e);
		// Replace with your favorite message dialog, e.g. GXT's MessageBox
		log(e, exceptionToDisplay);
		show(exceptionToDisplay);
	}

	protected abstract void show(Throwable exceptionToDisplay);

	protected void log(Throwable originalException, Throwable exceptionToDisplay) {
		// Logging to GWT log, so it appears in GWT log, and jul logger, so it may be transmitted
		// even to remote loggers.
		GWT.log("Unexpected exception client side", exceptionToDisplay);
		logger.log(Level.SEVERE, "Exception happened", exceptionToDisplay);
	}

	protected Throwable getExceptionToDisplay(Throwable throwable) {
		Throwable result = throwable;
		if (throwable instanceof UmbrellaException
				&& ((UmbrellaException) throwable).getCauses().size() == 1) {
			result = ((UmbrellaException) throwable).getCauses().iterator()
					.next();
		}
		return result;
	}
}