一。log4j的基础知识
1.log4j有三种主要组件:logger、appender and layout
2.Log4j提供的appender有以下几种:
org.apache.log4j.ConsoleAppender(控制台)
org.apache.log4j.FileAppender(文件)
org.apache.log4j.DailyRollingFileAppender(每天产生一个日志文件)
org.apache.log4j.RollingFileAppender(文件大小到达指定尺寸的时候产生一个新的文件)
org.apache.log4j.WriterAppender(将日志信息以流格式发送到任意指定的地方)
3.Log4j提供的layout有以下几种:
org.apache.log4j.HTMLLayout(以HTML表格形式布局)
org.apache.log4j.PatternLayout(可以灵活地指定布局模式)
org.apache.log4j.SimpleLayout(包含日志信息的级别和信息字符串)
org.apache.log4j.TTCCLayout(包含日志产生的时间、线程、类别等等信息)
4.Log4j提供的几种输出格式:
%M:Used to output the method name where the logging request was issued.
%m:Used to output the application supplied message associated with the logging event.
%l:Used to output location information of the caller which generated the logging event
%L:Used to output the line number from where the logging request was issued.
%p:Used to output the priority of the logging event.
%n:Outputs the platform dependent line separator character or characters.
%r:Used to output the number of milliseconds elapsed since the start of the application until the creation of the logging event.
%F:Used to output the file name where the logging request was issued.
%d:Used to output the date of the logging event.
%c:Used to output the category of the logging event
%C:Used to output the fully qualified class name of the caller issuing the logging request
5.如果是对于效率要求比较高的话,要在log.debug()之前加上log.isDebugEnabled()进行判断,这样能够大大减少执行时间
6.对于各个appenders,共有的属性是layout(一般设置为org.apache.log4j.PatternLayout),Threshold(Log的级别)
(1)ConsoleAppender:Target(System.out和System.err)
(2)FileAppender:File(定义输出的文件名),Append(定义是否为追加)
(3)DailyRollingFileAppender(除FileAppender属性外):MaxFileSize(最大文件大小),MaxBackupIndex()
以上来自http://www.wangchao.net.cn/bbsdetail_64587.html
二。详细配置log4j.xml文件
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration threshold="debug"
xmlns:log4j='http://jakarta.apache.org/log4j/'>
<appender name="console.CONSOLE"
class="org.apache.log4j.ConsoleAppender">
<param name="threshold" value="debug" />
<layout class="org.apache.log4j.PatternLayout">
<!--
<param name="ConversionPattern" value="%d{HH:mm:ss}[%C.%M(%L)-%p] %m%n"/>
-->
<param name="ConversionPattern" value="%d{HH:mm:ss}[%C(%L)-%p] %m%n"/>
</layout>
</appender>
<appender name="file.text.SYSFILE"
class="org.apache.log4j.RollingFileAppender">
<param name="threshold" value="error" />
<param name="file" value="/juyee.log" />
<param name="maxFileSize" value="2MB" />
<param name="maxBackupIndex" value="5" />
<param name="append" value="true" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern"
value="%-d{yyyy-MM-dd HH:mm:ss.SSS} [%p]-[%c] %m%n" />
</layout>
</appender>
<appender name="file.text.DATE_FILE"
class="org.apache.log4j.DailyRollingFileAppender">
<param name="threshold" value="debug" />
<param name="file" value="/juyee.log" />
<param name="append" value="true" />
<param name="datePattern" value="'.'yyyy-MM-dd" />
<!-- each hour
<param name="DatePattern" value="'.'yyyy-MM-dd-HH"/>
-->
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%d %-5p [%c] %m%n" />
</layout>
</appender>
<appender name="file.text.APPFILE"
class="org.apache.log4j.RollingFileAppender">
<param name="threshold" value="error" />
<param name="file" value="${webapp.root}/WEB-INF/logs/juyee.log" />
<param name="maxFileSize" value="1024KB" />
<param name="maxBackupIndex" value="5" />
<param name="append" value="true" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern"
value="%d %-5p %c - %m [%t] (%F:%L)%n" />
</layout>
</appender>
<appender name="file.html.HTML"
class="org.apache.log4j.RollingFileAppender">
<param name="threshold" value="error" />
<param name="file" value="/juyee-log.html" />
<param name="maxFileSize" value="1024KB" />
<param name="maxBackupIndex" value="5" />
<param name="append" value="true" />
<layout class="org.apache.log4j.HTMLLayout" />
</appender>
<appender name="file.xml.XML"
class="org.apache.log4j.RollingFileAppender">
<param name="threshold" value="error" />
<param name="file" value="/juyee-log.xml" />
<param name="maxFileSize" value="1024KB" />
<param name="maxBackupIndex" value="5" />
<param name="append" value="true" />
<layout class="org.apache.log4j.xml.XMLLayout" />
</appender>
<appender name="mail.MAIL" class="org.apache.log4j.net.SMTPAppender">
<param name="threshold" value="debug"/>
<!--
<param name="threshold" value="fatal"/>
-->
<param name="BufferSize" value="10"/>
<param name="From" value="yangguanjun@justonetech.com"/>
<param name="SMTPHost" value="www.justonetech.com"/>
<param name="Subject" value="juyee-log4jMessage"/>
<param name="To" value="yangguanjun@justonetech.com"/>
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="%-d{yyyy-MM-dd HH:mm:ss.SSS} [%p]-[%c] %m%n" />
</layout>
</appender>
<appender name="remote.CHAINSAW"
class="org.apache.log4j.net.SocketAppender">
<param name="threshold" value="fatal" />
<param name="remoteHost" value="localhost" />
<param name="port" value="4445" />
<param name="locationInfo" value="true" />
</appender>
<category name="com.juyee" additivity="true">
<priority value="info" />
<appender-ref ref="console.CONSOLE" />
<!--
<appender-ref ref="file.text.DATE_FILE" />
-->
</category>
<category name="com.co" additivity="true">
<priority value="debug" />
<appender-ref ref="console.CONSOLE" />
<appender-ref ref="file.text.DATE_FILE" />
</category>
<category name="org" additivity="true">
<priority value="WARN" />
<appender-ref ref="console.CONSOLE" />
<!--
<appender-ref ref="file.text.DATE_FILE" />
-->
</category>
<root>
<!--
<level value="trace" />
<level value="debug" />
<level value="info" />
<level value="warn" />
<level value="error" />
<level value="fatal" />
<appender-ref ref="console.CONSOLE" />
<appender-ref ref="file.text.DATE_FILE"/>
-->
</root>
</log4j:configuration>
Refer : http://dolphin-ygj.javaeye.com/blog/312504
三。加载log4j.xml
Refer : http://smilecertian.blog.sohu.com/52335422.html