Logger.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.log4j;

import org.apache.log4j.spi.LoggerFactory;

/**
 * This is the central class in the log4j package. Most logging operations, except configuration, are done through this
 * class.
 *
 * @author Ceki G&uuml;lc&uuml;
 * @since log4j 1.2
 */
public class Logger extends Category {

    /**
     * The fully qualified name of the Logger class. See also the getFQCN method.
     */
    private static final String FQCN = Logger.class.getName();

    protected Logger(String name) {
        super(name);
    }

    /**
     * Log a message object with the {@link Level#FINE FINE} level which is just an
     * alias for the {@link Level#DEBUG DEBUG} level.
     *
     * <p>
     * This method first checks if this category is <code>DEBUG</code> enabled by
     * comparing the level of this category with the {@link Level#DEBUG DEBUG}
     * level. If this category is <code>DEBUG</code> enabled, then it converts the
     * message object (passed as parameter) to a string by invoking the appropriate
     * {@link org.apache.log4j.or.ObjectRenderer}. It then proceeds to call all the
     * registered appenders in this category and also higher in the hierarchy
     * depending on the value of the additivity flag.
     *
     * <p>
     * <b>WARNING</b> Note that passing a {@link Throwable} to this method will
     * print the name of the <code>Throwable</code> but no stack trace. To print a
     * stack trace use the {@link #debug(Object, Throwable)} form instead.
     *
     * @param message the message object to log.
     */
    // public
    // void fine(Object message) {
    // if(repository.isDisabled(Level.DEBUG_INT))
    // return;
    // if(Level.DEBUG.isGreaterOrEqual(this.getChainedLevel())) {
    // forcedLog(FQCN, Level.DEBUG, message, null);
    // }
    // }

    /**
     * Log a message object with the <code>FINE</code> level including the stack
     * trace of the {@link Throwable} <code>t</code> passed as parameter.
     *
     * <p>
     * See {@link #fine(Object)} form for more detailed information.
     *
     * @param message the message object to log.
     * @param t       the exception to log, including its stack trace.
     */
    // public
    // void fine(Object message, Throwable t) {
    // if(repository.isDisabled(Level.DEBUG_INT))
    // return;
    // if(Level.DEBUG.isGreaterOrEqual(this.getChainedLevel()))
    // forcedLog(FQCN, Level.FINE, message, t);
    // }

    /**
     * Retrieve a logger named according to the value of the <code>name</code> parameter. If the named logger already
     * exists, then the existing instance will be returned. Otherwise, a new instance is created.
     *
     * <p>
     * By default, loggers do not have a set level but inherit it from their neareast ancestor with a set level. This is
     * one of the central features of log4j.
     *
     * @param name The name of the logger to retrieve.
     */
    static public Logger getLogger(String name) {
        return LogManager.getLogger(name);
    }

    /**
     * Shorthand for <code>getLogger(clazz.getName())</code>.
     *
     * @param clazz The name of <code>clazz</code> will be used as the name of the logger to retrieve. See
     *              {@link #getLogger(String)} for more detailed information.
     */
    static public Logger getLogger(Class clazz) {
        return LogManager.getLogger(clazz.getName());
    }

    /**
     * Return the root logger for the current logger repository.
     * <p>
     * The {@link #getName Logger.getName()} method for the root logger always returns string value: "root". However,
     * calling
     * <code>Logger.getLogger("root")</code> does not retrieve the root logger but a
     * logger just under root named "root".
     * <p>
     * In other words, calling this method is the only way to retrieve the root logger.
     */
    public static Logger getRootLogger() {
        return LogManager.getRootLogger();
    }

    /**
     * Like {@link #getLogger(String)} except that the type of logger instantiated depends on the type returned by the
     * {@link LoggerFactory#makeNewLoggerInstance} method of the
     * <code>factory</code> parameter.
     *
     * <p>
     * This method is intended to be used by sub-classes.
     *
     * @param name    The name of the logger to retrieve.
     * @param factory A {@link LoggerFactory} implementation that will actually create a new Instance.
     * @since 0.8.5
     */
    public static Logger getLogger(String name, LoggerFactory factory) {
        return LogManager.getLogger(name, factory);
    }

    /**
     * Log a message object with the {@link org.apache.log4j.Level#TRACE TRACE} level.
     *
     * @param message the message object to log.
     * @see #debug(Object) for an explanation of the logic applied.
     * @since 1.2.12
     */
    public void trace(Object message) {
        if (repository.isDisabled(Level.TRACE_INT)) {
            return;
        }

        if (Level.TRACE.isGreaterOrEqual(this.getEffectiveLevel())) {
            forcedLog(FQCN, Level.TRACE, message, null);
        }
    }

    /**
     * Log a message object with the <code>TRACE</code> level including the stack trace of the
     * {@link Throwable}<code>t</code> passed as parameter.
     *
     * <p>
     * See {@link #debug(Object)} form for more detailed information.
     * </p>
     *
     * @param message the message object to log.
     * @param t       the exception to log, including its stack trace.
     * @since 1.2.12
     */
    public void trace(Object message, Throwable t) {
        if (repository.isDisabled(Level.TRACE_INT)) {
            return;
        }

        if (Level.TRACE.isGreaterOrEqual(this.getEffectiveLevel())) {
            forcedLog(FQCN, Level.TRACE, message, t);
        }
    }

    /**
     * Check whether this category is enabled for the TRACE Level.
     *
     * @return boolean - <code>true</code> if this category is enabled for level TRACE, <code>false</code> otherwise.
     * @since 1.2.12
     */
    public boolean isTraceEnabled() {
        if (repository.isDisabled(Level.TRACE_INT)) {
            return false;
        }

        return Level.TRACE.isGreaterOrEqual(this.getEffectiveLevel());
    }

}