【Log4j日志输出】控制台输出、输出到文件：简单使用示例

官方下载

链接：Apache Log4j Download Mirrors

---

使用方式

下载完毕后解压：

复制jar包

把log4j-1.2.17.jar包放进项目里，添加到Java Build Path

在src同级目录创建log4j.properties

log4j.rootCategory=DEBUG, CONSOLE,LOGFILE

log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=-%p-%d{yyyy/MM/dd HH:mm:ss,SSS}-%l-%L-%m%n

log4j.appender.LOGFILE=org.apache.log4j.FileAppender
log4j.appender.logFile.Threshold=DEBUG
log4j.appender.logFile.ImmediateFlush=true
log4j.appender.LOGFILE.Append=true
log4j.appender.LOGFILE.File=C:/picture/mylog.log
log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
log4j.appender.LOGFILE.layout.ConversionPattern=-%p-%d{yyyy/MM/dd HH:mm:ss,SSS}-%l-%L-%m%n

---

代码示例

package cn.hanquan.test;

import org.apache.log4j.Logger;

public class TestLog4j {
	public static void main(String[] args) {
		Logger logger = Logger.getLogger(TestLog4j.class);

		// 记录debug级别的信息
		logger.debug("This is debug message.");
		// 记录info级别的信息
		logger.info("This is info message.");
		// 记录error级别的信息
		logger.error("This is error message.");
	}
}

---

输出结果

控制台

-DEBUG-2019/08/21 19:56:49,494-cn.hanquan.test.TestLog4j.main(TestLog4j.java:10)-10-This is debug message.
-INFO-2019/08/21 19:56:49,502-cn.hanquan.test.TestLog4j.main(TestLog4j.java:12)-12-This is info message.
-ERROR-2019/08/21 19:56:49,503-cn.hanquan.test.TestLog4j.main(TestLog4j.java:14)-14-This is error message.

log文件