下面以xml格式的log4j配置文件為例說明

view plaincopy to clipboardprint?
<?xml version="1.0" encoding="UTF-8"?> 
 
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd"> 
 
<log4j:configuration xmlns:log4j="http://jakarta./log4j/" debug="false"> 
 
  <appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender"> 
 
    <param name="Target" value="System.err"/> 
 
    <param name="Threshold" value="ALL"/> 
 
    <layout class="org.apache.log4j.PatternLayout"> 
 
      <param name="ConversionPattern" value="[%d{HH:mm:ss,SSS}][%p,%c{1}] %m%n"/> 
 
    </layout> 
 
  </appender> 
 
  <appender name="FILE" class="org.apache.log4j.RollingFileAppender"> 
 
    <param name="File" value="${log4jdir}/log.txt"/> 
 
    <param name="Threshold" value="ALL"/> 
 
    <param name="MaxFileSize" value="300KB"/> 
 
    <param name="MaxBackupIndex" value="20"/> 
 
    <layout class="org.apache.log4j.PatternLayout"> 
 
      <param name="ConversionPattern" value="[%d{HH:mm:ss,SSS}][%p,%c{1}] %m%n"/> 
 
    </layout> 
 
  </appender> 
 
   
 
  <root> 
 
    <level value="DEBUG"/> 
 
    <appender-ref ref="CONSOLE"/> 
 
    <appender-ref ref="FILE"/>    
 
  </root> 
 
</log4j:configuration> 

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration xmlns:log4j="http://jakarta./log4j/" debug="false">

  <appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender">

    <param name="Target" value="System.err"/>

    <param name="Threshold" value="ALL"/>

    <layout class="org.apache.log4j.PatternLayout">

      <param name="ConversionPattern" value="[%d{HH:mm:ss,SSS}][%p,%c{1}] %m%n"/>

    </layout>

  </appender>

  <appender name="FILE" class="org.apache.log4j.RollingFileAppender">

    <param name="File" value="${log4jdir}/log.txt"/>

    <param name="Threshold" value="ALL"/>

    <param name="MaxFileSize" value="300KB"/>

    <param name="MaxBackupIndex" value="20"/>

    <layout class="org.apache.log4j.PatternLayout">

      <param name="ConversionPattern" value="[%d{HH:mm:ss,SSS}][%p,%c{1}] %m%n"/>

    </layout>

  </appender>

  <root>

    <level value="DEBUG"/>

    <appender-ref ref="CONSOLE"/>

    <appender-ref ref="FILE"/> 

  </root>

</log4j:configuration>1 在log4j.xml配置文件中以 ${變量名} 寫路徑     <param name="File" value="${log4jdir}/log.txt"/>

2  在初始化log4j之前設(shè)置系統(tǒng)變量    

3 上面d:/webroot/log4j 是寫死了的, 但這個(gè)路徑可以根據(jù)實(shí)際情況動(dòng)態(tài)獲得     比如你想得到WEB-INF的上級(jí)路徑,可以這么寫 這樣解決相對(duì)web路徑的問題

view plaincopy to clipboardprint?
public String getWebRootPath(ServletContextEvent sce) {   
 
   return sce.getServletContext().getRealPath("/");   
 
} 

   public String getWebRootPath(ServletContextEvent sce) {

      return sce.getServletContext().getRealPath("/");

   }4 很多人喜歡直接把log4j.xml或log4j.properties文件放到classes下而不做DOMConfigurator.configure(log4jfile);這個(gè)操作,這時(shí)候可以在啟動(dòng)時(shí)可使用  java -Dlog4jdir=路徑

view plaincopy to clipboardprint?
System.setProperty("log4jdir","d:/webroot/log4j");           
 
String log4jfile = "log4j.xml";       
 
DOMConfigurator.configure(log4jfile);