Web.xml配置详解之listener

<listener>
<listen-class>com.myapp.MyListener</listen-class>
</listener>

　　

• 作用
  该元素用来注册一个监听器类。可以收到事件什么时候发生以及用什么作为响应的通知。事件监听程序在建立、修改和删除会话或servlet环境时得到通知。常与context-param联合使用。
• listen-class 指定监听类，该类继承ServletContextListener 包含初始化方法contextInitialized(ServletContextEvent event) 和 销毁方法contextDestoryed(ServletContextEvent event)
• 示例：初始化日志配置文件

•  <!--初始化日志配置文件 -->  
   <listener>  
       <listener-class>  
           com.myapp.LogbackConfigListener  
       </listener-class>  
   </listener>  
   <context-param>  
       <param-name>logbackConfigLocation</param-name>  
       <param-value>WEB-INF/logback.xml</param-value>  
   </context-param>  
  

  　　

  /**
   * 
   */
  package com.myapp;
  
  import javax.servlet.ServletContextEvent;
  import javax.servlet.ServletContextListener;
  import org.slf4j.Logger;  
  import org.slf4j.LoggerFactory;  
  import ch.qos.logback.classic.LoggerContext;  
  import ch.qos.logback.classic.joran.JoranConfigurator;  
  import ch.qos.logback.core.joran.spi.JoranException; 
  /**
   * @author louisliao
   *
   */
  public class LogbackConfigListener implements ServletContextListener {
  
  	private static final Logger logger = LoggerFactory.getLogger(LogbackConfigListener.class);  
  	private static final String CONFIG_LOCATION = "logbackConfigLocation";  
  	/* (non-Javadoc)
  	 * @see javax.servlet.ServletContextListener#contextDestroyed(javax.servlet.ServletContextEvent)
  	 */
  	public void contextDestroyed(ServletContextEvent arg0) {
  		// TODO Auto-generated method stub
  
  	}
  
  	/* (non-Javadoc)
  	 * @see javax.servlet.ServletContextListener#contextInitialized(javax.servlet.ServletContextEvent)
  	 */
  	public void contextInitialized(ServletContextEvent event) {
  		// TODO Auto-generated method stub
          String logbackConfigLocation = event.getServletContext().getInitParameter(CONFIG_LOCATION);  
          String fn = event.getServletContext().getRealPath(logbackConfigLocation);  
          try {  
              LoggerContext loggerContext = (LoggerContext)LoggerFactory.getILoggerFactory();  
              loggerContext.reset();  
              JoranConfigurator joranConfigurator = new JoranConfigurator();  
              joranConfigurator.setContext(loggerContext);  
              joranConfigurator.doConfigure(fn);  
              logger.debug("loaded slf4j configure file from {}", fn);  
          }  
          catch (JoranException e) {  
              logger.error("can loading slf4j configure file from " + fn, e);  
          }  
  
  	}
  
  }
  

  　转自　http://blog.csdn.net/liaoxiaohua1981/article/details/6760423