dubbo-common/src/main/java/com/alibaba/dubbo/common/logger/LoggerFactory.java

/*
 * Copyright 1999-2011 Alibaba Group.
 *  
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.dubbo.common.logger;

import java.io.File;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import com.alibaba.dubbo.common.extension.ExtensionLoader;
import com.alibaba.dubbo.common.logger.jcl.JclLoggerAdapter;
import com.alibaba.dubbo.common.logger.jdk.JdkLoggerAdapter;
import com.alibaba.dubbo.common.logger.log4j.Log4jLoggerAdapter;
import com.alibaba.dubbo.common.logger.slf4j.Slf4jLoggerAdapter;
import com.alibaba.dubbo.common.logger.support.FailsafeLogger;

/**
 * 日志输出器工厂
 * 
 * @author william.liangf
 */
public class LoggerFactory {

	private LoggerFactory() {
	}

	private static volatile LoggerAdapter LOGGER_ADAPTER;
	
	private static final ConcurrentMap<String, FailsafeLogger> LOGGERS = new ConcurrentHashMap<String, FailsafeLogger>();

	// 查找常用的日志框架
	static {
	    String logger = System.getProperty("dubbo.application.logger");
	    if ("slf4j".equals(logger)) {
    		setLoggerAdapter(new Slf4jLoggerAdapter());
    	} else if ("jcl".equals(logger)) {
    		setLoggerAdapter(new JclLoggerAdapter());
    	} else if ("log4j".equals(logger)) {
    		setLoggerAdapter(new Log4jLoggerAdapter());
    	} else if ("jdk".equals(logger)) {
    		setLoggerAdapter(new JdkLoggerAdapter());
    	} else {
    		try {
    			setLoggerAdapter(new Log4jLoggerAdapter());
            } catch (Throwable e1) {
                try {
                	setLoggerAdapter(new Slf4jLoggerAdapter());
                } catch (Throwable e2) {
                    try {
                    	setLoggerAdapter(new JclLoggerAdapter());
                    } catch (Throwable e3) {
                        setLoggerAdapter(new JdkLoggerAdapter());
                    }
                }
            }
    	}
	}
	
	public static void setLoggerAdapter(String loggerAdapter) {
	    if (loggerAdapter != null && loggerAdapter.length() > 0) {
	        setLoggerAdapter(ExtensionLoader.getExtensionLoader(LoggerAdapter.class).getExtension(loggerAdapter));
	    }
	}

	/**
	 * 设置日志输出器供给器
	 * 
	 * @param loggerAdapter
	 *            日志输出器供给器
	 */
	public static void setLoggerAdapter(LoggerAdapter loggerAdapter) {
		if (loggerAdapter != null) {
			Logger logger = loggerAdapter.getLogger(LoggerFactory.class.getName());
			logger.info("using logger: " + loggerAdapter.getClass().getName());
			LoggerFactory.LOGGER_ADAPTER = loggerAdapter;
			for (Map.Entry<String, FailsafeLogger> entry : LOGGERS.entrySet()) {
				entry.getValue().setLogger(LOGGER_ADAPTER.getLogger(entry.getKey()));
			}
		}
	}

	/**
	 * 获取日志输出器
	 * 
	 * @param key
	 *            分类键
	 * @return 日志输出器, 后验条件: 不返回null.
	 */
	public static Logger getLogger(Class<?> key) {
		FailsafeLogger logger = LOGGERS.get(key.getName());
		if (logger == null) {
			LOGGERS.putIfAbsent(key.getName(), new FailsafeLogger(LOGGER_ADAPTER.getLogger(key)));
			logger = LOGGERS.get(key.getName());
		}
		return logger;
	}

	/**
	 * 获取日志输出器
	 * 
	 * @param key
	 *            分类键
	 * @return 日志输出器, 后验条件: 不返回null.
	 */
	public static Logger getLogger(String key) {
		FailsafeLogger logger = LOGGERS.get(key);
		if (logger == null) {
			LOGGERS.putIfAbsent(key, new FailsafeLogger(LOGGER_ADAPTER.getLogger(key)));
			logger = LOGGERS.get(key);
		}
		return logger;
	}
	
	/**
	 * 动态设置输出日志级别
	 * 
	 * @param level 日志级别
	 */
	public static void setLevel(Level level) {
		LOGGER_ADAPTER.setLevel(level);
	}

	/**
	 * 获取日志级别
	 * 
	 * @return 日志级别
	 */
	public static Level getLevel() {
		return LOGGER_ADAPTER.getLevel();
	}
	
	/**
	 * 获取日志文件
	 * 
	 * @return 日志文件
	 */
	public static File getFile() {
		return LOGGER_ADAPTER.getFile();
	}

}