Log4jLogger.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.openejb.log.logger;

import org.apache.log4j.Appender;
import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;
import org.apache.log4j.Priority;
import org.apache.log4j.spi.LoggingEvent;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.logging.Handler;
import java.util.logging.Level;
import java.util.logging.LogRecord;

/**
 * java.util.logging.Logger implementation delegating to Log4j.
 * All methods can be used except:
 * setLevel
 * addHandler / getHandlers
 * setParent / getParent
 * setUseParentHandlers / getUseParentHandlers
 *
 * @author gnodet
 */
public class Log4jLogger extends AbstractDelegatingLogger {
    private static final Map<Level, org.apache.log4j.Level> TO_LOG4J = new HashMap<Level, org.apache.log4j.Level>();
    private static final org.apache.log4j.Level TRACE;

    private final Logger log;

    static {
        //older versions of log4j don't have TRACE, use debug
        org.apache.log4j.Level t = org.apache.log4j.Level.DEBUG;
        try {
            final Field f = org.apache.log4j.Level.class.getField("TRACE");
            t = (org.apache.log4j.Level) f.get(null);
        } catch (final Throwable ex) {
            //ignore, assume old version of log4j
        }
        TRACE = t;

        TO_LOG4J.put(Level.ALL, org.apache.log4j.Level.ALL);
        TO_LOG4J.put(Level.SEVERE, org.apache.log4j.Level.ERROR);
        TO_LOG4J.put(Level.WARNING, org.apache.log4j.Level.WARN);
        TO_LOG4J.put(Level.INFO, org.apache.log4j.Level.INFO);
        TO_LOG4J.put(Level.CONFIG, org.apache.log4j.Level.DEBUG);
        TO_LOG4J.put(Level.FINE, org.apache.log4j.Level.DEBUG);
        TO_LOG4J.put(Level.FINER, TRACE);
        TO_LOG4J.put(Level.FINEST, TRACE);
        TO_LOG4J.put(Level.OFF, org.apache.log4j.Level.OFF);
    }

    public Log4jLogger(final String name, final String resourceBundleName) {
        super(name, resourceBundleName);
        log = LogManager.getLogger(name);
    }

    public Level getLevel() {
        final org.apache.log4j.Level l = log.getEffectiveLevel();
        if (l != null) {
            return fromL4J(l);
        }
        return null;
    }

    public void setLevel(final Level newLevel) throws SecurityException {
        log.setLevel(TO_LOG4J.get(newLevel));
    }

    public synchronized void addHandler(final Handler handler) throws SecurityException {
        log.addAppender(new HandlerWrapper(handler));
    }

    public synchronized void removeHandler(final Handler handler) throws SecurityException {
        log.removeAppender("HandlerWrapper-" + handler.hashCode());
    }

    public synchronized Handler[] getHandlers() {
        final List<Handler> ret = new ArrayList<Handler>();
        final Enumeration<?> en = log.getAllAppenders();
        while (en.hasMoreElements()) {
            final Appender ap = (Appender) en.nextElement();
            if (ap instanceof HandlerWrapper) {
                ret.add(((HandlerWrapper) ap).getHandler());
            }
        }
        return ret.toArray(new Handler[ret.size()]);
    }

    protected void internalLogFormatted(final String msg, final LogRecord record) {
        log.log(AbstractDelegatingLogger.class.getName(),
            TO_LOG4J.get(record.getLevel()),
            msg,
            record.getThrown());
    }


    private Level fromL4J(final org.apache.log4j.Level l) {
        Level l2 = null;
        switch (l.toInt()) {
            case org.apache.log4j.Level.ALL_INT:
                l2 = Level.ALL;
                break;
            case org.apache.log4j.Level.FATAL_INT:
                l2 = Level.SEVERE;
                break;
            case org.apache.log4j.Level.ERROR_INT:
                l2 = Level.SEVERE;
                break;
            case org.apache.log4j.Level.WARN_INT:
                l2 = Level.WARNING;
                break;
            case org.apache.log4j.Level.INFO_INT:
                l2 = Level.INFO;
                break;
            case org.apache.log4j.Level.DEBUG_INT:
                l2 = Level.FINE;
                break;
            case org.apache.log4j.Level.OFF_INT:
                l2 = Level.OFF;
                break;
            default:
                if (l.toInt() == TRACE.toInt()) {
                    l2 = Level.FINEST;
                }
        }
        return l2;
    }


    private class HandlerWrapper extends AppenderSkeleton {
        Handler handler;

        public HandlerWrapper(final Handler h) {
            handler = h;
            name = "HandlerWrapper-" + h.hashCode();
        }

        public Handler getHandler() {
            return handler;
        }

        @Override
        protected void append(final LoggingEvent event) {
            final LogRecord lr = new LogRecord(fromL4J(event.getLevel()),
                event.getMessage().toString());
            lr.setLoggerName(event.getLoggerName());
            if (event.getThrowableInformation() != null) {
                lr.setThrown(event.getThrowableInformation().getThrowable());
            }
            final String rbname = getResourceBundleName();
            if (rbname != null) {
                lr.setResourceBundleName(rbname);
                lr.setResourceBundle(getResourceBundle());
            }
            handler.publish(lr);
        }

        public void close() {
            handler.close();
            closed = true;
        }

        public boolean requiresLayout() {
            return false;
        }

        @Override
        public Priority getThreshold() {
            return TO_LOG4J.get(handler.getLevel());
        }

        @Override
        public boolean isAsSevereAsThreshold(final Priority priority) {
            final Priority p = getThreshold();
            return p == null || priority.isGreaterOrEqual(p);
        }
    }
}