java-org.hwo/src/org/hwo/logging/Logging.java

package org.hwo.logging;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.text.DateFormat;
import java.util.Date;
import java.util.LinkedList;
import java.util.List;

public class Logging {

	private static Logging _inst;
	private static PrintStream	liveStream;
	
	
	private PrintStream	logStream;
	private final DateFormat dateFormat;
	
	List<LoggingListener> loggingListeners;
	
	public Logging(String filename){
		loggingListeners = new LinkedList<LoggingListener>();
		
		dateFormat = DateFormat.getDateTimeInstance();
		try {
			
			File f = new File(filename);
			File fold = new File(String.format("%s.old", filename));
			
			if (fold.exists()){
				fold.delete();
			}
			
			if (f.exists()){
				f.renameTo(fold);
			}
			
			logStream = new PrintStream(filename);

		} catch (FileNotFoundException e) {
			liveStream.println("----!!!!! LOGGING ERROR !!!!!-----");
			e.printStackTrace();
		}

		System.setErr(new PrintStream(new LoggingOutputStream(LogLevel.ERROR)));
		System.setOut(new PrintStream(new LoggingOutputStream(LogLevel.INFO)));
		
	}
	
	public void addLoggingListener(LoggingListener listener){
		loggingListeners.add(listener);
	}
	public void removeLoggingListener(LoggingListener listener){
		loggingListeners.remove(listener);
	}
	
	private void _log(LogLevel logLevel,String message){
		String formattedLine;
		
		formattedLine = String.format("%s [%-8s] %s", dateFormat.format(new Date()),logLevel.toString(),message);
		
		logStream.println(formattedLine);
		logStream.flush();
		
		if (liveStream != null){
			liveStream.println(formattedLine);
			liveStream.flush();
		}
		
		for (LoggingListener l: loggingListeners){
			l.logMessageArrived(formattedLine);
		}
	}
	
	
	static public void setLogFileName(String logFileName){
		_inst = new Logging(logFileName);
	}
	
	static public void log(LogLevel logLevel,String message){
		if (_inst == null){
			_inst = new Logging("application.log");
		}
		_inst._log(logLevel, message);
	}
	
	static public void log(String message){
		log(LogLevel.INFO,message);
	}
	
	static public void log(LogLevel logLevel,String message,Object... args){
		log(logLevel,String.format(message, args));
	}

	static public void log(String message,Object... args){
		log(LogLevel.INFO,message,args);
	}

	static public void log(Exception e){
		log(LogLevel.ERROR,"An Exception occured: %s [%s]",e.getClass().getName(), e.getMessage());
		e.printStackTrace();
	}
	
	static public Logging getInstance() {
		return _inst;
	}
	
	static {
		liveStream = System.out;
	}
	
	
	public class LoggingOutputStream extends OutputStream {

		byte[]	buffer;
		int		bufferPosition;
		
		LogLevel
				logLevel;
		
		public LoggingOutputStream() {
			buffer = new byte[4096];
			bufferPosition = 0;
			this.logLevel = LogLevel.INFO;
		}

		public LoggingOutputStream(LogLevel logLevel) {
			buffer = new byte[4096];
			bufferPosition = 0;
			this.logLevel = logLevel;
		}
		
		@Override
		public void flush(){
			if (bufferPosition > 0){
				_log(this.logLevel,new String(buffer,0,bufferPosition));
				bufferPosition = 0;
			};
		}
		
		@Override
		public void write(int b) throws IOException {
			if (b == 0x0A){
				
				flush();
				
			} else {
				buffer[bufferPosition++] = new Integer(b).byteValue();
				
				if (bufferPosition == buffer.length){
					flush();
				}
			};
			
		}
		
		
		
	}
	
}