colorconsoleappender.java

sea是一个基于seda模式的实现。这个设计模式将系统分为很多stage。每个stage分布不同的任务（基于线程池）。通过任务流的方式提高系统的效率。

/*
 * Copyright (c) 2003, The Regents of the University of California, through
 * Lawrence Berkeley National Laboratory (subject to receipt of any required
 * approvals from the U.S. Dept. of Energy). All rights reserved.
 */
package gov.lbl.dsd.sea.nio.util;

import org.apache.log4j.ConsoleAppender;
import org.apache.log4j.Layout;
import org.apache.log4j.Level;
import org.apache.log4j.spi.LoggingEvent;

/**
 * Log4J Appender which prints to System.out and shows different log levels in
 * different colors; very useful for effectively sieving through large number of
 * log messages. Colors are used only on Unix, and ignored on Windows because we
 * don't know how to do it. (If it's possible and you know how, submit a
 * patch!); If you wish to use this appender let log4j know about it by adding
 * "log4j.appender.CONSOLE=gov.lbl.dsd.sea.nio.util.ColorConsoleAppender" to the
 * log4j.properties file.
 * 
 * @author [e-mail]
 * @author $Author: hoschek3 $
 * @version $Revision: 1.1 $, $Date: 2004/06/17 18:34:39 $
 */
public class ColorConsoleAppender extends ConsoleAppender {

	private static final char ESCAPE = 033;
	private static final String UNESCAPE = "[m";
	private static final String REVERSE = "[7m";

	private static final String BLACK = "[30m";
	private static final String RED = "[31m";
	private static final String GREEN = "[32m";
	private static final String YELLOW = "[33m";
	private static final String BLUE = "[34m";
	private static final String PURPLE = "[35m";
	private static final String CYAN = "[36m";
	private static final String SILVER = "[37m";
	private static final String WHITE = "[38m";		

	private static final boolean isWindows = System.getProperty("os.name").startsWith("Windows");

	// overridden
	protected void subAppend(LoggingEvent event) {
		this.qw.write(formatEvent(event));

		if (layout.ignoresThrowable()) {
			String[] s = event.getThrowableStrRep();
			if (s != null) {
				int len = s.length;
				for (int i = 0; i < len; i++) {
					if (!isWindows) {
						this.qw.write(toColorString(event.getLevel()).toString());						
					}
					this.qw.write(s[i]);
					if (!isWindows) {
						this.qw.write(ESCAPE + UNESCAPE);						
					}
					this.qw.write(Layout.LINE_SEP);
				}
			}
		}

		if (this.immediateFlush) {
			this.qw.flush();
		}
	}

	protected String formatEvent(LoggingEvent event) {

		String toPrint = this.layout.format(event);
		if (isWindows) {
			return toPrint;
		} 
		else {
			StringBuffer s = this.toColorString(event.getLevel());
			
			//remove newline
			s.append(toPrint.substring(0, toPrint.length() - 1));

			// reset colors
			s.append(ESCAPE).append(UNESCAPE);
			
			s.append(Layout.LINE_SEP);
			return s.toString();
		}

	}

	protected StringBuffer toColorString(Level level) {
		StringBuffer s = new StringBuffer(2);
		s.append(ESCAPE);
		
		switch (level.toInt()) {
			case Level.ERROR_INT:
				s.append(RED);
				break;
			case Level.WARN_INT:
				s.append(PURPLE);
				break;
			case Level.INFO_INT:
				s.append(GREEN);
				break;
			case Level.FATAL_INT:
				s.append(RED).append(ESCAPE).append(REVERSE);
				break;
			case Level.DEBUG_INT:
				s.append(BLUE);
				break;
			default:
				s.append(CYAN);
				break;
		}
		return s;
	}
}