EclipseLogAppender.java

/*******************************************************************************
 * Copyright (c) 2008 itemis AG (http://www.itemis.eu) and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 *******************************************************************************/
package org.eclipse.incquery.patternlanguage.emf.ui;

import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.Level;
import org.apache.log4j.PatternLayout;
import org.apache.log4j.Priority;
import org.apache.log4j.spi.LoggingEvent;
import org.eclipse.core.runtime.ILog;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.Status;
import org.eclipse.incquery.patternlanguage.emf.ui.internal.EMFPatternLanguageActivator;

/**
 * Updated Eclipse LogAppender based on the implementation in org.eclipse.xtext.logger bundle.
 * 
 * @author Peter Friese - Initial contribution and API
 * @author Sven Efftinge
 * @author Knut Wannheden - Refactored handling when used in non OSGi environment
 * @author Zoltan Ujhelyi - updated for the use of EMF-IncQuery
 */
public class EclipseLogAppender extends AppenderSkeleton {

    private static final String LOG_PATTERN = "%m%n";

    private static final String BUNDLE_NAME = EMFPatternLanguageActivator.getInstance().getBundle().getSymbolicName();

    private boolean initialized;
    private ILog log;

    public EclipseLogAppender() {
        super();
        layout = new PatternLayout(LOG_PATTERN);
    }

    public EclipseLogAppender(boolean isActive) {
        super(isActive);
        layout = new PatternLayout(LOG_PATTERN);
    }

    private synchronized void ensureInitialized() {
        if (!initialized) {
            log = Platform.getLog(Platform.getBundle(BUNDLE_NAME));
            initialized = true;
        }
    }

    private ILog getLog() {
        ensureInitialized();
        return log;
    }

    @Override
    protected void append(LoggingEvent event) {
        if (isDoLog(event.getLevel())) {
            String logString = layout.format(event);

            ILog myLog = getLog();
            if (myLog != null) {
                String loggerName = event.getLoggerName();
                int severity = mapLevel(event.getLevel());
                final Throwable throwable = event.getThrowableInformation() != null ? event.getThrowableInformation()
                        .getThrowable() : null;
                IStatus status = createStatus(severity, loggerName, logString, throwable);
                getLog().log(status);
            }
        }
    }

    private boolean isDoLog(Level level) {
        return level.toInt() >= Priority.WARN_INT;
    }

    private int mapLevel(Level level) {
        switch (level.toInt()) {
        case Priority.DEBUG_INT:
        case Priority.INFO_INT:
            return IStatus.INFO;

        case Priority.WARN_INT:
            return IStatus.WARNING;

        case Priority.ERROR_INT:
        case Priority.FATAL_INT:
            return IStatus.ERROR;

        default:
            return IStatus.INFO;
        }
    }

    private IStatus createStatus(int severity, String loggerName, String message, Throwable throwable) {
        return new Status(severity, BUNDLE_NAME, message, throwable);
    }

    public void close() {
    }

    public boolean requiresLayout() {
        return true;
    }

}