简单的日志框架

/**
 * 日志记录器接口
 *
 * @author yourname (mailto:[e-mail])
 */
public interface ILogger {

	boolean isDebugEnabled();

	boolean isInfoEnabled();

	boolean isWarnEnabled();

	boolean isErrorEnabled();


	void debug(Object message);

	void debug(Object message, Object[] params);

	void debug(Throwable t);

	void debug(Object message, Throwable t);

	void debug(Object message, Object[] params, Throwable t);


	void info(Object message);

	void info(Object message, Object[] params);

	void info(Throwable t);

	void info(Object message, Throwable t);

	void info(Object message, Object[] params, Throwable t);


	void warn(Object message);

	void warn(Object message, Object[] params);

	void warn(Throwable t);

	void warn(Object message, Throwable t);

	void warn(Object message, Object[] params, Throwable t);


	void error(Object message);

	void error(Object message, Object[] params);

	void error(Throwable t);

	void error(Object message, Throwable t);

	void error(Object message, Object[] params, Throwable t);
}

/**
 * 日志工厂
 *
 * @author yourname (mailto:[e-mail])
 */
public class DebugLoggerFactory {

	private static LoggerFactoryPlugin logFactory = new LoggerFactoryPlugin(null);

	public static void setLoggerProvider(ILoggerProvider provider) {
		synchronized (DebugLoggerFactory.class) {
			logFactory = new LoggerFactoryPlugin(provider);
		}
	}
	
	/**
	 * 动态刷新
	 *
	 */
	public static void refresh() {
		logFactory.refresh();
	}

	/**
	 * 取得日志记录器
	 *
	 * @param clazz
	 * @return 日志记录器
	 */
	public static ILogger getLogger(Class clazz) {
		return logFactory.getLogger(clazz);
	}

	/**
	 * 取得日志记录器
	 *
	 * @param loggerName 日志名称
	 * @return 日志记录器
	 */
	public static ILogger getLogger(String loggerName) {
		return logFactory.getLogger(loggerName);
	}
}

/**
 * 日志提供商
 *
 * @author yourname (mailto:[e-mail])
 */
public interface ILoggerProvider {

	/**
	 * 取得日志实例
	 *
	 * @param loggerName 日志名称
	 * @return 日志实例
	 */
	ILogger createLogger(String loggerName);
}

/**
 * 日志抽象实现
 *
 * @author yourname (mailto:[e-mail])
 */
public abstract class AbstractLogger implements ILogger {

	public void debug(Object message) {
		if (message != null && message instanceof Throwable) {
			debug(null, null, (Throwable)message);
			return;
		}
		debug(message, null, null);
	}

	public void debug(Object message, Object[] params) {
		debug(message, params, null);
	}

	public void debug(Throwable t) {
		debug(null, null, t);
	}

	public void debug(Object message, Throwable t) {
		debug(message, null, t);
	}

	public void debug(Object message, Object[] params, Throwable t) {
		if (isDebugEnabled()) {
			doDebug(formatMessage(message, params), t);
		}
	}

	abstract protected void doDebug(String message, Throwable t);

	public void info(Object message) {
		if (message != null && message instanceof Throwable) {
			info(null, null, (Throwable)message);
			return;
		}
		info(message, null, null);
	}

	public void info(Object message, Object[] params) {
		info(message, params, null);
	}

	public void info(Throwable t) {
		info(null, null, t);
	}

	public void info(Object message, Throwable t) {
		info(message, null, t);
	}

	public void info(Object message, Object[] params, Throwable t) {
		if (isInfoEnabled()) {
			doInfo(formatMessage(message, params), t);
		}
	}

	abstract protected void doInfo(String message, Throwable t);

	public void warn(Object message) {
		if (message != null && message instanceof Throwable) {
			warn(null, null, (Throwable)message);
			return;
		}
		warn(message, null, null);
	}

	public void warn(Object message, Object[] params) {
		warn(message, params, null);
	}

	public void warn(Throwable t) {
		warn(null, null, t);
	}

	public void warn(Object message, Throwable t) {
		warn(message, null, t);
	}

	public void warn(Object message, Object[] params, Throwable t) {
		if (isWarnEnabled()) {
			doWarn(formatMessage(message, params), t);
		}
	}

	abstract protected void doWarn(String message, Throwable t);

	public void error(Object message) {
		if (message != null && message instanceof Throwable) {
			error(null, null, (Throwable)message);
			return;
		}
		error(message, null, null);
	}

	public void error(Object message, Object[] params) {
		error(message, params, null);
	}

	public void error(Throwable t) {
		error(null, null, t);
	}

	public void error(Object message, Throwable t) {
		error(message, null, t);
	}

	public void error(Object message, Object[] params, Throwable t) {
		if (isErrorEnabled()) {
			doError(formatMessage(message, params), t);
		}
	}

	abstract protected void doError(String message, Throwable t);
	
	protected String formatMessage(Object message, Object[] params) {
		StringBuilder buf = new StringBuilder();		
		if (message != null) {
			if (message instanceof String) {
				String msg = (String) message;
				if (msg.trim().length() > 0) {
					if (params != null && params.length > 0) {
						message = new MessageFormat(msg).format(params);
					}
				}
			}
			buf.append(message);
		}
		return buf.toString();
	}
}

/**
 * 日志工厂实现
 *
 * @author Administrator
 *
 */
public class LoggerFactoryPlugin {
	
	private ILoggerProvider _provider = null;
	
	private WeakHashMap<String, LoggerWrapper> logWeakMap = new WeakHashMap<String, LoggerWrapper>();
	
	private Object lock = new Object();

	public LoggerFactoryPlugin(ILoggerProvider provider) {
		this._provider = provider;
	}
	
	/**
	 * 刷新
	 *
	 */
	public void refresh() {
		for (Entry<String, LoggerWrapper> entry : logWeakMap.entrySet()) {
			entry.getValue().logger = doGetLogger(entry.getKey()).logger;
		}
	}
	
	/**
	 * 取得日志记录器
	 *
	 * @param clazz
	 * @return 日志记录器
	 */
	public ILogger getLogger(Class clazz) {
		return getLogger(clazz == null ? "null" : clazz.getName());
	}

	/**
	 * 取得日志记录器
	 *
	 * @param loggerName 日志名称
	 * @return 日志记录器
	 */
	public ILogger getLogger(String loggerName) {
		if (loggerName == null) {
			loggerName = "null";
		}
		LoggerWrapper log = doGetLogger(loggerName);
		synchronized(lock) {
			logWeakMap.put(loggerName, log);
		}		
		return log;
	}
	
	private LoggerWrapper doGetLogger(String loggerName) {
		
		ILogger log = _provider != null ? _provider.createLogger(loggerName) : null;
		if (!(log instanceof LoggerWrapper)) {
			log = new LoggerWrapper(loggerName, log);
		}
		return (LoggerWrapper)log;
	}
}

/**
 * 日志包裹（防止记录日志时抛出异常）
 *
 * @author yourname (mailto:[e-mail])
 */
public class LoggerWrapper extends AbstractLogger {

	ILogger logger = null;

	@SuppressWarnings("unused")
	private String name = null;

	public LoggerWrapper(String name, ILogger logger) {
		this.name = name;
		if (logger == null) {
			return;
		}
		if (logger instanceof LoggerWrapper) {
			this.logger = ((LoggerWrapper)logger).logger;
		} else {
			this.logger = logger;
		}
	}

	public boolean isDebugEnabled() {
		if (logger == null) {
			return true;
		}
		try {
			return logger.isDebugEnabled();
		} catch (Throwable t) {
			return false;
		}
	}

	public boolean isInfoEnabled() {
		if (logger == null) {
			return true;
		}
		try {
			return logger.isInfoEnabled();
		} catch (Throwable t) {
			return false;
		}
	}

	public boolean isWarnEnabled() {
		if (logger == null) {
			return true;
		}
		try {
			return logger.isWarnEnabled();
		} catch (Throwable t) {
			return false;
		}
	}

	public boolean isErrorEnabled() {
		if (logger == null) {
			return true;
		}
		try {
			return logger.isErrorEnabled();
		} catch (Throwable t) {
			return false;
		}
	}

	protected void doDebug(String message, Throwable t) {
		try {
			logger.debug(message, t);
		} catch (Throwable e) {
			try {
				System.out.println(convert("DEBUG", message, t));
			} catch (Throwable ignore) {

			}
		}
	}

	protected void doInfo(String message, Throwable t) {

		try {
			logger.info(message, t);
		} catch (Throwable e) {
			try {
				System.out.println(convert(" INFO", message, t));
			} catch (Throwable ignore) {

			}
		}
	}

	protected void doWarn(String message, Throwable t) {
		try {
			logger.warn(message, t);
		} catch (Throwable e) {
			try {
				System.err.println(convert(" WARN", message, t));
			} catch (Throwable ignore) {

			}
		}
	}

	protected void doError(String message, Throwable t) {
		try {
			logger.error(message, t);
		} catch (Throwable e) {
			try {
				System.err.println(convert("ERROR", message, t));
			} catch (Throwable ignore) {

			}
		}
	}

	private String convert(String level, Object message, Throwable t) {
		StringBuilder buf = new StringBuilder();
		buf.append("[").append(format(System.currentTimeMillis(), "yyyy-MM-dd HH:mm:ss")).append("]");
		buf.append("[").append(level).append("]");
//		if (name != null && name.trim().length() > 0) {
//			buf.append("[").append(name).append("]");
//		}
		buf.append("[").append(message).append("]");

		if (t != null) {
			String error_msg = t.getMessage();
			if (error_msg != null) {
				buf.append("[").append(error_msg).append("]");
			}

			buf.append("\n");
			StringWriter sw = new StringWriter();
			t.printStackTrace(new PrintWriter(sw));
			buf.append(sw.toString());
		}
		return buf.toString();
	}

	private static String format(long time, String pattern) {
		SimpleDateFormat dateFormat = new SimpleDateFormat();
		dateFormat.applyPattern(pattern);
		return dateFormat.format(new Date(time));
	}

}