Logger.java

package com.github.markusbernhardt.proxy.util;

/*****************************************************************************
 * Simple logging support for the framework. You need to add an logging listener
 * that needs to send the logging events to an backend.
 *
 * @author Markus Bernhardt, Copyright 2016
 * @author Bernd Rosstauscher, Copyright 2009
 ****************************************************************************/

public class Logger {

	public enum LogLevel {
		ERROR, WARNING, INFO, TRACE, DEBUG
	}

	/*****************************************************************************
	 * Interface for an logging backend that can be attached to the logger.
	 ****************************************************************************/

	public interface LogBackEnd {

		/*************************************************************************
		 * Invoked for every logging event.
		 * 
		 * @param clazz
		 *            the class that sends the log message.
		 * @param loglevel
		 *            the logging level.
		 * @param msg
		 *            the message format string.
		 * @param params
		 *            the message parameters for the format string.
		 ************************************************************************/

		public void log(Class<?> clazz, LogLevel loglevel, String msg, Object... params);

		/*************************************************************************
		 * Can be used to test if a given logging level is enabled.
		 * 
		 * @param logLevel
		 *            the loglevel to test.
		 * @return true if enabled, else false.
		 ************************************************************************/

		public boolean isLogginEnabled(LogLevel logLevel);
	}

	private static LogBackEnd backend;

	/*************************************************************************
	 * Gets the currently attached logging backend.
	 * 
	 * @return Returns the backend.
	 ************************************************************************/

	public static LogBackEnd getBackend() {
		return backend;
	}

	/*************************************************************************
	 * Attaches a new logging backend replacing the existing one.
	 * 
	 * @param backend
	 *            The backend to set.
	 ************************************************************************/

	public static void setBackend(LogBackEnd backend) {
		Logger.backend = backend;
	}

	/*************************************************************************
	 * Logs a message.
	 * 
	 * @param clazz
	 *            the class that sends the log message.
	 * @param loglevel
	 *            the logging level.
	 * @param msg
	 *            the message format string.
	 * @param params
	 *            the message parameters for the format string.
	 ************************************************************************/

	public static void log(Class<?> clazz, LogLevel loglevel, String msg, Object... params) {
		if (backend != null) {
			backend.log(clazz, loglevel, msg, params);
		}
	}

	/*************************************************************************
	 * Can be used to test if a given logging level is enabled.
	 * 
	 * @param logLevel
	 *            the loglevel to test.
	 * @return true if enabled, else false.
	 ************************************************************************/

	public static boolean isLogginEnabled(LogLevel logLevel) {
		if (backend != null) {
			return backend.isLogginEnabled(logLevel);
		}
		return false;
	}

}