学步园

一、下载log4j.jar包

二、配置log4j.properties文件(当然也可用log4j.xml，这里就不多说了) ，配置如下：

log4j.rootLogger=DEBUG, fileLogger,BORROW
#fileLogger
log4j.appender.fileLogger=org.apache.log4j.RollingFileAppender
log4j.appender.fileLogger.File=E://log.log
log4j.appender.fileLogger.MaxFileSize=10MB

log4j.appender.fileLogger.MaxBackupIndex=100
log4j.appender.fileLogger.layout=org.apache.log4j.PatternLayout
log4j.appender.fileLogger.layout.ConversionPattern=%d [%-5p]  %c %m%n

### Appender for Admin related messages ###
log4j.appender.BORROW=org.apache.log4j.ConsoleAppender
###log4j.appender.ADMIN.File=log/admin.log
log4j.appender.BORROW.layout=org.apache.log4j.PatternLayout
log4j.appender.BORROW.layout.ConversionPattern=%d [%-5p] - %c %m%n

 三、JAVA实现代码：

package com.log4j.test;

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

public class TestLog4j {
    private Logger log = Logger.getLogger(TestLog4j.class);
    public TestLog4j() {
        configlog4j.config();
    }

    public void testprint1() {
        log.debug("debug test");
        log.info("info test");
        log.warn("warn test");
        log.error("error test");
    }

    public static void main(String[] args) {
        TestLog4j test = new TestLog4j();
        test.testprint1();

    }
}

class configlog4j {
    public static void config() {
        String connectdir=TestLog4j.class.getResource("log4j.properties").getPath();
        System.out.println("url:::>> " + connectdir);
        PropertyConfigurator.configure(connectdir);
    }
}

注：log4j.properties文件一定和当前运行的class放在同一目录下