DMDirc-Parser/src/com/dmdirc/parser/irc/Logging.java

/*
 * Copyright (c) 2006-2009 Chris Smith, Shane Mc Cormack, Gregory Holmes
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.dmdirc.parser.irc;

import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;

/**
 * Logging using log4j if available.
 */
public class Logging {
    /** Available Log Levels */
    public enum LogLevel {
        TRACE("trace", "isTraceEnabled"),
        DEBUG("debug", "isDebugEnabled"),
        INFO("info", "isInfoEnabled"),
        WARN("warn", "isWarnEnabled"),
        ERROR("error", "isErrorEnabled"),
        FATAL("fatal", "isFatalEnabled");
        
        /** Method name */
        private final String methodName;
        
        /** Check Method name */
        private final String checkMethodName;
        
        /**
         * Create a new LogLevel
         *
         * @param methodName Name of method in log4j to log to
         * @param checkMethodName Name of method in log4j to sue to check logging
         */
        private LogLevel(final String methodName, final String checkMethodName) {
            this.methodName = methodName;
            this.checkMethodName = checkMethodName;
        }
        
        /**
         * Get the Name of method in log4j to log to
         *
         * @return Name of method in log4j to log to
         */
        public String getMethodName() { return methodName; }
        
        /**
         * Get the Name of the check method in log4j
         *
         * @return Name of check method in log4j
         */
        public String getCheckMethodName() { return checkMethodName; }
    };
    
    /** Singleton Instance of Logging. */
    private static Logging me;
    
    /** Is log4j available. */
    private final boolean isAvailable;
    
    /** "Log" object if available. */
    private Object log = null;
    
    /**
     * Get an instance of Logging.
     *
     * @return The instance of Logging
     */
    public static Logging getLogging() {
        if (me == null) { me = new Logging(); }
        return me;
    }
    
    /** Create a new Logging. */
    @SuppressWarnings("unchecked")
    private Logging() {
        boolean classExists = false;
        try {
            Class factory = null;
            // Check for classes
            Class.forName("org.apache.commons.logging.Log");
            factory = Class.forName("org.apache.commons.logging.LogFactory");
        
            classExists = (factory != null);
            if (classExists) {
                final Method getLog = factory.getMethod("getLog", new Class[]{Class.class});
                log = getLog.invoke(null, this.getClass());
            }
        } catch (ClassNotFoundException cnfe) {
        } catch (NoSuchMethodException nsme) {
        } catch (IllegalAccessException iae) {
        } catch (InvocationTargetException ite) {
        }
        
        isAvailable = (classExists && log != null);
    }
    
    /**
     * Check is a log level is available.
     *
     * @param level Level to check
     */
    public boolean levelEnabled(final LogLevel level) {
        if (isAvailable) {
            try {
                final Method check = log.getClass().getMethod(level.getCheckMethodName(), new Class[0]);
                return (Boolean)check.invoke(log, new Object[0]);
            } catch (NoSuchMethodException nsme) {
            } catch (IllegalAccessException iae) {
            } catch (InvocationTargetException ite) {
            }
        }
        
        return false;
    }
    
    /**
     * Log a message if log4j is available.
     *
     * @param level Level to log at
     * @param message Message to log
     */
    public void log(final LogLevel level, final String message) {
        log(level, message, null);
    }
    
    /**
     * Log a message if log4j is available.
     *
     * @param level Level to log at
     * @param message Message to log
     * @param throwable Throwable to log alongside message
     */
    public void log(final LogLevel level, final String message, final Throwable throwable) {
        if (!isAvailable) { return; }
        try {
            if (throwable == null) {
                final Method method = log.getClass().getMethod(level.getMethodName(), new Class[]{String.class});
                method.invoke(log, new Object[]{message});
            } else {
                final Method method = log.getClass().getMethod(level.getMethodName(), new Class[]{String.class, Throwable.class});
                method.invoke(log, new Object[]{message, throwable});
            }
        } catch (NoSuchMethodException nsme) {
        } catch (IllegalAccessException iae) {
        } catch (InvocationTargetException ite) {
        }
    }
}