2、加入jar包 log4j.jar

3、配置log4j.properties

log4j.rootLogger=DEBUG,CONSOLE,FILE,DailyRollingFile,RollingFile,EFile

#Console
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%d [%t] %-5p %c - %m%n

#File
log4j.appender.FILE = org.apache.log4j.DailyRollingFileAppender
log4j.appender.FILE.File =d:\\log\\log_File\\log.log
log4j.appender.FILE.Append = true
log4j.appender.FILE.Threshold = ERROR
log4j.appender.FILE.layout = org.apache.log4j.PatternLayout
log4j.appender.FILE.layout.ConversionPattern =%d [%t] %-5p %c - %m%n

#DailyRollingFile
log4j.appender.DailyRollingFile=org.apache.log4j.DailyRollingFileAppender
log4j.appender.DailyRollingFile.File = d:\\log\\log_DailyRollingFile\\log.log
log4j.appender.DailyRollingFile.layout = org.apache.log4j.PatternLayout
log4j.appender.DailyRollingFile.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n
 
#RollingFile
log4j.appender.RollingFile = org.apache.log4j.RollingFileAppender
log4j.appender.RollingFile.File = d:\\log\\log_RollingFile\\log.log
log4j.appender.RollingFile.MaxFileSize=1KB
log4j.appender.RollingFile.MaxBackupIndex=3
log4j.appender.RollingFile.layout = org.apache.log4j.PatternLayout
log4j.appender.RollingFile.layout.ConversionPattern =%d [%t] %-5p [%c] - %m%n

#EFile
log4j.appender.EFile = org.apache.log4j.RollingFileAppender
log4j.appender.EFile.File = d:\\log\\log_EFile\\log.log
log4j.appender.EFile.MaxFileSize=1KB
log4j.appender.EFile.MaxBackupIndex=3
log4j.appender.EFile.layout = org.apache.log4j.PatternLayout
log4j.appender.EFile.layout.ConversionPattern =%d [%t] %-5p [%c] - %m%n

4、测试java类

package testLog4j;
import org.apache.log4j.Logger;
public class Test {
    private static Logger logger=Logger.getLogger(Test.class); 
    public static void main(String[] args) {
        for(int i=0;i<10;i++){
        logger.info("Info");
        logger.debug("debug");
        logger.error("error");
        logger.fatal("fatal");
        logger.warn("warn");
        System.out.println("----------------- "+i+"   ---------------------");
        }
    }
}

5、结果

a）、

# 将 ERROR 日志输出到 FILE 文件（Threshold=ERROR）
# DEBUG 日志输出到Console、DailyRollingFile、RollingFile、EFile。

b）、

# 两者结果相同，RollingFile 和 EFile 是文件名，对结果无影响
# EFile
log4j.appender.EFile = org.apache.log4j.RollingFileAppender
# RollingFile
log4j.appender.RollingFile = org.apache.log4j.RollingFileAppender

c）、

# File
# 输出类型：
log4j.appender.FILE = org.apache.log4j.DailyRollingFileAppender
# 输出路径：
log4j.appender.xxx.File =d:\\log\\log_EFile\\log.log
# 是否追加：
log4j.appender.FILE.Append = true
# FILE 日志级别：
log4j.appender.FILE.Threshold = ERROR
# 自定义输出格式：
log4j.appender.FILE.layout = org.apache.log4j.PatternLayout
log4j.appender.FILE.layout.ConversionPattern =%d [%t] %-5p %c - %m%n

# RollingFile
# 文件最大容量为1kb
log4j.appender.RollingFile.MaxFileSize=1KB
# 文件最大数量为3
log4j.appender.RollingFile.MaxBackupIndex=3

6、可能遇到的错误

1) Logger cannot be resolved to  a type
原因：log4j.jar包导入出错，重新导入并buildPath

2) log4j中Logger.getLogger()加载一个类提示错误错误提示如下：
 The method getLogger(String) in the type Logger is not applicable 
for the arguments (Class)
原因：你import的不会是java.util.logging.Logger吧？
要导入import org.apache.log4j.Logger.Logger

文章引用
http://blog.java1234.com/blog/q.html