myservletcontextlistener.java

JSP高级程序员网络开发源代码

package com.jspdev.ch8;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextAttributeEvent;
import javax.servlet.ServletContextAttributeListener;
import java.io.*;


public final class MyServletContextListener
    implements ServletContextListener,ServletContextAttributeListener {
   
    private ServletContext context = null;

    /**
     *以下代码实现ServletContextListener接口。
     */
    public void contextDestroyed(ServletContextEvent sce) {

	logout("contextDestroyed()-->ServletContext被销毁");
	   this.context = null;

    }

    public void contextInitialized(ServletContextEvent sce) {

	this.context = sce.getServletContext();
	logout("contextInitialized()-->ServletContext初始化了");

    }//ServletContextListener
    
    /**
     *以下代码实现 ServletContextAttributeListener接口
     */    
    public void attributeAdded(ServletContextAttributeEvent scae) {

	logout("增加了一个ServletContext属性：attributeAdded('" + scae.getName() + "', '" +
	    scae.getValue() + "')");

    }

    public void attributeRemoved(ServletContextAttributeEvent scae) {

	logout("删除了一个ServletContext属性：attributeRemoved('" + scae.getName() + "', '" +
	    scae.getValue() + "')");

    }


    public void attributeReplaced(ServletContextAttributeEvent scae) {

	logout("某个ServletContext的属性被改变：attributeReplaced('" + scae.getName() + "', '" +
	    scae.getValue() + "')");

    }

    private void logout(String message) {	
	    
	    PrintWriter out=null;
	    try
	    {
	    	out=new PrintWriter(new FileOutputStream("c:\\test.txt",true));
	    	out.println(new java.util.Date().toLocaleString()+"::Form ContextListener: " + message);
	    	out.close();
	    }
	    catch(Exception e)
	    {
	    	out.close();
	    	e.printStackTrace();
	    }

    }  

}