com.devbliss.gwtbliss.client.ExceptionPreBootstrapper.java Source code

Introduction

Here is the source code for com.devbliss.gwtbliss.client.ExceptionPreBootstrapper.java

Source

/*
 * Copyright 2013, devbliss GmbH
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.devbliss.gwtbliss.client;

import java.util.logging.Logger;

import com.google.gwt.core.client.GWT;
import com.google.gwt.core.client.GWT.UncaughtExceptionHandler;
import com.google.gwt.user.client.DOM;
import com.google.gwt.user.client.ui.DialogBox;
import com.gwtplatform.mvp.client.PreBootstrapper;

/**
 * Add an uncaught exception handler which shows unhandled exceptions.
 *
 * @author <a href="mailto:jb@barop.de">Johannes Barop</a>
 *
 */
public class ExceptionPreBootstrapper implements PreBootstrapper {

    private static final Logger LOG = Logger.getLogger(ExceptionPreBootstrapper.class.getName());

    @Override
    public void onPreBootstrap() {
        GWT.setUncaughtExceptionHandler(new UncaughtExceptionHandler() {
            @Override
            public void onUncaughtException(final Throwable e) {
                LOG.severe(getStacktrace(e));
                GWT.log("UncaughtException!", e);
                showExceptionPopup(e);
            }
        });
    }

    /**
     * @return The stacktrace to the given exception.
     */
    private String getStacktrace(final Throwable throwable) {
        String stacktrace = "";
        Throwable cur = throwable;

        while (cur != null) {
            final StackTraceElement[] stackTraceElements = cur.getStackTrace();
            stacktrace += cur.toString() + "\n";
            for (int i = 0; i < stackTraceElements.length; i++) {
                stacktrace += "    at " + stackTraceElements[i] + "\n";
            }
            cur = cur.getCause();
            if (cur != null) {
                stacktrace += "Caused by: ";
            }
        }

        return stacktrace;
    }

    /**
     * Shows the given exception to the user.
     */
    private void showExceptionPopup(final Throwable e) {
        final String output = getQuote() + getStacktrace(e);

        final DialogBox dialogBox = new DialogBox(true, false);
        DOM.setStyleAttribute(dialogBox.getElement(), "backgroundColor", "#ABCDEF");
        dialogBox.setHTML("<pre style='font-family: monospace; font-size: 0.8em; margin: 0; padding: 10px;'>"
                + output + "</pre>");
        dialogBox.center();
    }

    /**
     * @return A shocking quote which is shown in the HTML output.
     */
    private String getQuote() {
        String quote = "";

        quote += "[The crew waits quietly as a Reaver ship passes.] \n";
        quote += "Simon: What happens if they board us?  \n";
        quote += "Zoe:   If they take the ship, they'll rape us to death, eat our flesh, and sew our skins into their clothing. \n";
        quote += "       And if we're very, very lucky they'll do it in that order. \n\n";

        return quote;
    }

}