（log4j入门）举例说明 log4j 的配置文件

入门级别，老鸟勿进

• log4j可以用多个配置文件 。（多开发组用自己不同的配置文件时很方便）
• 配置文件中能用系统属性 。（动态设定配置的值，比如输出文件路径）
• 配置文件也能放在Jar文件中 一起打包。

net.tianyu.test.log4j.MyMain.java

package net.tianyu.test.log4j;

import org.apache.log4j.Logger;
import org.apache.log4j.xml.DOMConfigurator;

public class MyMain {

	public static void main(String[] args) {
		new MyMain();
	}

	public MyMain() {

		// set system property
		System.setProperty("net.tianyu.logfilename", "MyMain");

		// load init file
		DOMConfigurator.configure(getClass().getResource(
						"/conf/log4j/log_conf_core.xml").getPath());
		DOMConfigurator.configure(getClass().getResource(
						"/conf/log4j/log_conf_ui.xml").getPath());

		// get logger
		Logger uiLogger = Logger.getLogger("uiLogger");
		Logger coreLogger = Logger.getLogger("coreLogger");

		uiLogger.fatal("ui fatal");
		coreLogger.error("core error");
		uiLogger.warn("ui warn");
		coreLogger.info("core info");
		uiLogger.debug("ui debug");
	}
}

 

conf.log4j.log_conf_ui.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/" >
  <appender name="uiAppender" class="org.apache.log4j.ConsoleAppender">
     <param name="Target" value="System.out" /> 
     <layout class="org.apache.log4j.PatternLayout">
        <param name="ConversionPattern" value="%d %5p %c{1} - %m%n" />
     </layout>
  </appender>
  
  <category name="uiLogger" >
    <priority value ="info" />
    <appender-ref ref="uiAppender" />
  </category>
</log4j:configuration>
 

 

conf.log4j.log_conf_core.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
	<appender name="coreStdoutAppender" class="org.apache.log4j.ConsoleAppender">
		<param name="Target" value="System.out" />
		<layout class="org.apache.log4j.PatternLayout">
			<param name="ConversionPattern" value="%d %5p %c{1} - %m%n" />
		</layout>
	</appender>

	<appender name="coreFileAppender" class="org.apache.log4j.FileAppender">
		<param name="File" value="${net.tianyu.logfilename}_mylog.log" />
		<param name="Append" value="true" />
		<layout class="org.apache.log4j.PatternLayout">
			<param name="ConversionPattern" value="%d %5p %c{1} - %m%n" />
		</layout>
	</appender>


	<category name="coreLogger">
		<priority value="info" />
		<appender-ref ref="coreStdoutAppender" />
		<appender-ref ref="coreFileAppender" />
	</category>
</log4j:configuration>