Log4j简单应用

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Log4j主页：http://logging.apache.org/

Log4j是一款强大的日志记录工具，允许用户对日志记录作出灵活的定义。

测试程序：

package org.eleaf.log4j;

import java.io.IOException;
import java.util.Properties;

import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;

public class Log4jTest {
static Logger logger = Logger.getLogger(Log4jTest.class.getClass()); //定义日志记录器
/**
* @param args
*/
public static void main(String[] args) {
  Properties property = new Properties();
  try {
   property.load(Log4jTest.class.getResourceAsStream("log4jtest.properties")); //获取属性文件
  } catch (IOException e) {
  }
  PropertyConfigurator.configure(property);
  logger.info("Begin Log4jTest");
  for (int i = 0; i < 10; i++)
  {
   try
   {
    int j = random(); //返回一个0-9的随机数。
    logger.warn(i + "/" + j + "=" + (i/j)); //如果分母为0,抛出异常，记录error;否则记录warn.
   } catch (Exception e) {
    logger.error("error:" + e.getMessage());
   }
  }
  logger.info("End Log4jTest");
}
private static int random() //返回一个0-9的随机数。
{
  return (int)(Math.random()*10);
}

}

log4jtest.properties属性文件：(应与Log4jTest.class在同一目录中）

##info指明日志级别，stdout,file是两个不同的输出目的地。

log4j.rootLogger=info, stdout, file

##输出目的地stdout，即标准输出。

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

##定义输出格式：
log4j.appender.stdout.layout.ConversionPattern=[run:%r][date:%d{yyyy-MM-dd HH:mm:ss}][catalog:%c][priority:%p][message:%m][location:%l][thread:%t]%n

##输出目的地file，输出到文件log4jtest.log。

log4j.appender.file=org.apache.log4j.FileAppender
log4j.appender.file.File=log4jtest.log
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=[run:%r][date:%d{yyyy-MM-dd HH:mm:ss}][catalog:%c][priority:%p][message:%m][location:%l][thread:%t]%n

控制台标准输出结果：

[run:0][date:2005-10-18 17:16:58][catalog:java.lang.Class][priority:INFO][message:Begin Log4jTest][location:org.eleaf.log4j.Log4jTest.main(Log4jTest.java:22)][thread:main]
[run:31][date:2005-10-18 17:16:58][catalog:java.lang.Class][priority:WARN][message:0/8=0][location:org.eleaf.log4j.Log4jTest.main(Log4jTest.java:28)][thread:main]
[run:31][date:2005-10-18 17:16:58][catalog:java.lang.Class][priority:WARN][message:1/1=1][location:org.eleaf.log4j.Log4jTest.main(Log4jTest.java:28)][thread:main]
[run:47][date:2005-10-18 17:16:58][catalog:java.lang.Class][priority:WARN][message:2/8=0][location:org.eleaf.log4j.Log4jTest.main(Log4jTest.java:28)][thread:main]
[run:47][date:2005-10-18 17:16:58][catalog:java.lang.Class][priority:ERROR][message:error:/ by zero][location:org.eleaf.log4j.Log4jTest.main(Log4jTest.java:30)][thread:main]
[run:47][date:2005-10-18 17:16:58][catalog:java.lang.Class][priority:WARN][message:4/4=1][location:org.eleaf.log4j.Log4jTest.main(Log4jTest.java:28)][thread:main]
[run:47][date:2005-10-18 17:16:58][catalog:java.lang.Class][priority:ERROR][message:error:/ by zero][location:org.eleaf.log4j.Log4jTest.main(Log4jTest.java:30)][thread:main]
[run:47][date:2005-10-18 17:16:58][catalog:java.lang.Class][priority:WARN][message:6/9=0][location:org.eleaf.log4j.Log4jTest.main(Log4jTest.java:28)][thread:main]
[run:47][date:2005-10-18 17:16:58][catalog:java.lang.Class][priority:WARN][message:7/4=1][location:org.eleaf.log4j.Log4jTest.main(Log4jTest.java:28)][thread:main]
[run:47][date:2005-10-18 17:16:58][catalog:java.lang.Class][priority:WARN][message:8/1=8][location:org.eleaf.log4j.Log4jTest.main(Log4jTest.java:28)][thread:main]
[run:47][date:2005-10-18 17:16:58][catalog:java.lang.Class][priority:WARN][message:9/9=1][location:org.eleaf.log4j.Log4jTest.main(Log4jTest.java:28)][thread:main]
[run:47][date:2005-10-18 17:16:58][catalog:java.lang.Class][priority:INFO][message:End Log4jTest][location:org.eleaf.log4j.Log4jTest.main(Log4jTest.java:33)][thread:main]

日志文件输出结果：