Logger.java

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * 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.motorolamobility.preflighting.core.internal.logging;

import java.io.IOException;
import java.net.URL;
import java.util.HashMap;
import java.util.Properties;

import org.apache.log4j.Level;
import org.apache.log4j.PropertyConfigurator;

import com.motorolamobility.preflighting.core.PreflightingCorePlugin;

/**
 * Logger provides a logging facility to the <b>MOTODEV Studio</b> based
 * applications such as Studios and RCP applications. </p> <b>Note:</b> The logs
 * will be saved on the plug-in state area for this plug-in.
 */
public final class Logger
{

    /**
     * Configure Log4J
     */
    static
    {
        URL log4jProperties =
                PreflightingCorePlugin.getContext().getBundle().getResource("etc/log4j.properties");
        Properties p = new Properties();
        try
        {
            p.load(log4jProperties.openStream());
            PropertyConfigurator.configure(p);
        }
        catch (IOException e)
        {
            //Do Nothing.
        }
    }

    /*
     * This Map pools the Logger instances.
     */
    private static HashMap<String, Logger> pool;

    /*
     * Log4j logger instance being wrapped.
     */
    private final org.apache.log4j.Logger logger;

    /**
     * Builds a logger associated to the specified name.
     * 
     * @param name The name of the logger.
     */
    private Logger(String name)
    {
        logger = org.apache.log4j.Logger.getLogger(name);
    }

    /**
     * Gets a logger named according to the value of the name parameter. If the
     * named logger already exists, then the existing instance will be returned.
     * Otherwise, a new instance is created.
     * 
     * @param name The name of the logger.
     * @return the logger associated to the specified name.
     */
    public static synchronized Logger getLogger(String name)
    {
        Logger logger = null;
        if (pool == null)
        {
            pool = new HashMap<String, Logger>();
        }

        if (pool.containsKey(name))
        {
            logger = pool.get(name);
        }
        else
        {
            logger = new Logger(name);
            pool.put(name, logger);
        }
        return logger;
    }

    /**
     * Logs the specified message with the specified level.
     * 
     * @param level The log level.
     * @param message The message to log.
     */
    public void log(int level, String message)
    {
        boolean key = true;
        if ((level == com.motorolamobility.preflighting.core.logging.Level.OFF)
                || (level == com.motorolamobility.preflighting.core.logging.Level.ALL))
        {
            key = false;
        }

        if (key)
        {
            logger.log(Level.toLevel(level), message);
        }
    }

    /**
     * Logs the specified message and an exception stack trace.
     * 
     * @param level The log level.
     * @param message The message to log.
     * @param exception Exception whose stack will be logged.
     */
    public void log(int level, String message, Throwable exception)
    {
        boolean key = true;
        if ((level == com.motorolamobility.preflighting.core.logging.Level.OFF)
                || (level == com.motorolamobility.preflighting.core.logging.Level.ALL))
        {
            key = false;
        }
        if (key)
        {
            logger.log(Level.toLevel(level), message, exception);
        }
    }

    /**
     * Log a message object with the DEBUG level.
     * 
     * @param message The message to log.
     */
    public void debug(String message)
    {
        debug(message, null);
    }

    /**
     * Log a message object with the DEBUG level.
     * 
     * @param message The message to log.
     * @param exception Exception whose stack will be logged.
     */
    public void debug(String message, Throwable exception)
    {
        if (null == exception)
        {
            logger.debug(message);
        }
        else
        {
            logger.debug(message, exception);
        }
    }

    /**
     * Log a message object with the INFO level.
     * 
     * @param message The message to log.
     */
    public void info(String message)
    {
        info(message, null);
    }

    /**
     * Log a message object with the INFO level.
     * 
     * @param message The message to log.
     * @param exception Exception whose stack will be logged.
     */
    public void info(String message, Throwable exception)
    {
        if (null == exception)
        {
            logger.info(message);
        }
        else
        {
            logger.info(message, exception);
        }
    }

    /**
     * Log a message object with the WARN level.
     * 
     * @param message The message to log.
     */
    public void warn(String message)
    {
        warn(message, null);
    }

    /**
     * Log a message object with the WARN level.
     * 
     * @param message The message to log.
     * @param exception Exception whose stack will be logged.
     */
    public void warn(String message, Throwable exception)
    {
        if (null == exception)
        {
            logger.warn(message);
        }
        else
        {
            logger.warn(message, exception);
        }
    }

    /**
     * Log a message object with the ERROR level.
     * 
     * @param message The message to log.
     */
    public void error(String message)
    {
        error(message, null);
    }

    /**
     * Log a message object with the ERROR level.
     * 
     * @param message The message to log.
     * @param exception Exception whose stack will be logged.
     */
    public void error(String message, Throwable exception)
    {
        if (null == exception)
        {
            logger.error(message);
        }
        else
        {
            logger.error(message, exception);
        }
    }

    /**
     * Log a message object with the FATAL level.
     * 
     * @param message The message to log.
     */
    public void fatal(String message)
    {
        fatal(message, null);
    }

    /**
     * Log a message object with the FATAL level.
     * 
     * @param message The message to log.
     * @param exception Exception whose stack will be logged.
     */
    public void fatal(String message, Throwable exception)
    {
        if (null == exception)
        {
            logger.fatal(message);
        }
        else
        {
            logger.fatal(message, exception);
        }
    }

    /**
     * Sets the Logger level to the specified value.
     * 
     * @param level One of the {@link com.motorolamobility.preflighting.core.logging.Level}
     *            constants.
     */
    public void setLevel(int level)
    {
        logger.setLevel(Level.toLevel(level));
    }
}