Log4j 简单配置

首先，当然是下载jar包：http://logging.apache.org/log4j/1.2/download.html

其次，import到工程中，我这里用的intellij，导入方法：

File -> project structure -> module -> dependencies
点击 ‘+’ 选择第一项 ‘jars or directories’ 

然后，要注意log4j.properties的位置，应放在/src/main/resources里面，配置信息：

log4j.rootLogger= debug,stdout,D,E
#
#### 输出信息到控制抬 ###
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 = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n
### 输出DEBUG 级别以上的日志到=E://logs/error.log ###
log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = /Users/xfli/Documents/design-patterns/log.log
log4j.appender.D.Append = true
log4j.appender.D.Threshold = DEBUG
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n
### 输出ERROR 级别以上的日志到=E://logs/error.log ###
log4j.appender.E = org.apache.log4j.DailyRollingFileAppender
log4j.appender.E.File =/Users/xfli/Documents/design-patterns/error.log
log4j.appender.E.Append = true
log4j.appender.E.Threshold = ERROR
log4j.appender.E.layout = org.apache.log4j.PatternLayout
log4j.appender.E.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n
Set root logger level to DEBUG and its only appender to A1.

最后就可以在main方法中测试啦：

package net.lixufei.weather;
import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.Logger;

public class WeatherStation {

private static Logger logger = Logger.getLogger(WeatherStation.class);

public static void main (String[] args) {

logger.debug("This is debug message.");
logger.info("This is info message.");
logger.error("This is error message.");
}
}

。

运行之后，控制台会打印出：

[DEBUG] 2016-10-12 08:18:51,193 method:net.lixufei.weather.WeatherStation.main(WeatherStation.java:11)

This is debug message.

[INFO ] 2016-10-12 08:18:51,195 method:net.lixufei.weather.WeatherStation.main(WeatherStation.java:12)

This is info message.

[ERROR] 2016-10-12 08:18:51,195 method:net.lixufei.weather.WeatherStation.main(WeatherStation.java:13)

This is error message.

并且，也会生成error.log和log.log的文件。