如何配置使用 Log4j

最近在用Java 写一个FTP上传下载文件工具，正好需要产生操作日志。

利用Log4j.jar可以轻松解决。下面介绍一下Log4j的使用，具体概念到官网查阅：

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1、下载：

http://archive.apache.org/dist/logging/log4j/

2、添加jar到java项目：

3、创建：Log4j.Properties文件，放在src文件夹下即可：

3.1 输出到console端：

# Root logger option
log4j.rootLogger=INFO, stdout
 
# Direct log messages to stdout 
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

3.2 输出到日志文件：

# Root logger option
log4j.rootLogger=INFO, file
 
# Direct log messages to a log file
log4j.appender.file=org.apache.log4j.RollingFileAppender
log4j.appender.file.File=C:\\loging.log
log4j.appender.file.MaxFileSize=1MB
log4j.appender.file.MaxBackupIndex=1
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

3.3 输出到console同时输出到日志文件：

# Root logger option
log4j.rootLogger=INFO, file, stdout
 
# Direct log messages to a log file
log4j.appender.file=org.apache.log4j.RollingFileAppender
log4j.appender.file.File=C:\\loging.log
log4j.appender.file.MaxFileSize=1MB
log4j.appender.file.MaxBackupIndex=1
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n
 
# Direct log messages to stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

3.4 按天roll over（翻滚，转存）日志：

# Root logger option
log4j.rootLogger=INFO,console,dailyFile
##Daily log:
log4j.appender.dailyFile=org.apache.log4j.DailyRollingFileAppender
log4j.appender.dailyFile.File=e:/ftplog/autoftp.log
log4j.appender.dailyFile.Append=true
log4j.appender.dailyFile.layout=org.apache.log4j.PatternLayout  
log4j.appender.dailyFile.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p - %m%n
log4j.appender.dailyFile.Threshold=INFO
log4j.appender.dailyFile.DatePattern='.'yyyy-MM-dd  

# Direct log messages to console
log4j.appender.console=org.apache.log4j.ConsoleAppender
log4j.appender.console.Threshold=INFO
log4j.appender.console.ImmediateFlush=true
log4j.appender.console.Target=System.out
log4j.appender.console.layout=org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

PS：

Debug Level: 日志记录等级

We have used DEBUG with both the appenders. All the possible options are:

TRACE
DEBUG
INFO
WARN
ERROR
FATAL
ALL

Daily Log File Generation: 每日文件生成模式

DatePattern	Description
'.' yyyy-MM	Roll over at the end of each month and the beginning of the next month.
'.' yyyy-MM-dd	This is the default value and roll over at midnight each day.
'.' yyyy-MM-dd-a	Roll over at midday and midnight of each day.
'.' yyyy-MM-dd-HH	Roll over at the top of every hour.
'.' yyyy-MM-dd-HH-mm	Roll over every minute.
'.' yyyy-ww	Roll over on the first day of each week depending upon the locale.

4、测试代码如下：

import org.apache.log4j.Logger;
    import org.apache.log4j.BasicConfigurator;
    
    public class Hello {
    
      static Logger logger = Logger.getLogger(Hello.class);
    
      public
      static
      void main(String argv[]) {
    	BasicConfigurator.configure();
    	logger.debug("Hello world.");
    	logger.info("What a beatiful day.");
      }
    }

Output：

2013-12-14 13:02:06 ERROR Hello:12 - Hello world.
2013-12-14 13:02:06 INFO Hello:13 - What a beatiful day.

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Dylan presents.