Log4j的使用

Log4j可以很好的进行程序的跟踪：

1.首先编写log4j.properties，这个在网上有很多，可以直接拿过来使用

log4j.rootLogger=debug, stdout, R
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n

log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=./example.log
log4j.appender.R.MaxFileSize= 100KB

# Keep one backup file
log4j.appender.R.MaxBackupIndex=1

log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n     

2.添加log4j-1.2.16.jar到工程中，如果不行也可添加logging-log4j-1.2.9.jar

3.写一个测试类：

import org.apache.log4j.Logger;

public class Log4jTest {
	
	static Logger logger = Logger.getLogger(Log4jTest.class.getName());
    public static void main(String[] args) {
      // BasicConfigurator replaced with PropertyConfigurator.
      logger.info("Entering application.");
      logger.info("Exiting application.");
      logger.debug("Exiting application.");
    }
}