log.java

FIRE (Flexible Interface Rendering Engine)是一个J2ME上的灵活的图形界面引擎

/*
 * Fire (Flexible Interface Rendering Engine) is a set of graphics widgets for creating GUIs for j2me applications. 
 * Copyright (C) 2006-2008 Bluevibe (www.bluevibe.net)
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * 
 */

package gr.fire.util;

/**
 * Utility class for easily logging on fire application.
 * 
 * It writes the messages sent to it using the Log.logInfo, Log.logWarn, Log.logError and Log.logDebug 
 * methods to one or more predefined Loggers.
 * 
 * The default logger is standard output. The developer can add more loggers or set a different (remove standard out) logger.
 *  
 * @see #setLogDestination(Logger)
 * @see #addLogDestination(Logger)
 * @see Logger
 * @author padeler
 *
 */
public final class Log
{
	/**
	 * Flag to enable or disable debuging information. If false the calls to Log.logDebug will not produce any output.
	 */
	public static boolean showDebug=false;
	
	private static Logger[] out;
	
	static{
		Logger l = new Logger(){
			public void println(String txt)
			{
				System.out.println(txt);
			}
		};
		out = new Logger[]{l};
	}
	
	private Log()
	{
	}
	
	/**
	 * Sets the only logger to be the given.
	 * @param l the new logger. All previous loggers are removed.
	 */
	public static void setLogDestination(Logger l)
	{
		Log.out= new Logger[]{l};
	}
	/**
	 * Adds the given logger to the loggers list. 
	 * All loggers will receive the output.
	 * @param o
	 */
	public static void addLogDestination(Logger o)
	{
		if(o==null) return;
		
		if(out==null){
			out = new Logger[]{o};
			return;
		}
		
		Logger []old =out;
		out = new Logger[old.length+1];
		for(int i =0 ;i<old.length;++i)
		{
			out[i] = old[i];
		}
		out[old.length] = o;
	}
	
	public static void logInfo(String str)
	{
		if(out!=null)
		{
			for(int i=0;i<out.length;++i)
				out[i].println("INFO: "+str);
		}
	}
	
	public static void logError(String str,Throwable e)
	{
		if(out!=null)
		{
			for(int i=0;i<out.length;++i)
			{
				Logger o = out[i];
				o.println("ERROR: "+str);
				if(e!=null)
				{
					o.println("ERROR: "+e.getClass().getName());
					o.println("ERROR: "+e.getMessage());
					e.printStackTrace();
				}
			}
		}
	}

	public static void logWarn(String str, Throwable e)
	{
		if(out!=null)
		{
			for(int i=0;i<out.length;++i)
			{
				Logger o = out[i];
				o.println("WARN: "+str);
				if(e!=null)
				{
					o.println("WARN: "+e.getClass().getName());
					o.println("WARN: "+e.getMessage());
					e.printStackTrace();
				}
			}
		}
	}
	
	public static void logWarn(String str)
	{
		if(out!=null)
		{
			for(int i=0;i<out.length;++i)
				out[i].println("WARN: "+str);
		}
	}
	
	/**
	 * Writes str to all the registed loggers only is the flag {@link #showDebug} is set to true.
	 * @param str
	 */
	public static void logDebug(String str)
	{
		if(showDebug && out!=null)
		{
			for(int i=0;i<out.length;++i)
				out[i].println("DEBUG: "+str);
		}
	}
}