applicationlistener.java

一个基于java工厂模式的 的实现

/*
 * ApplicationListener.java
 *
 * Created on 2007年4月28日, 下午1:44
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package com.ebuy.web.listeners;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;

/**
 *
 * @author Administrator
 */
public class ApplicationListener implements javax.servlet.ServletContextListener
{
    
    /** Creates a new instance of ApplicationListener */
    public ApplicationListener()
    {
    }

    public void contextInitialized(ServletContextEvent sce)
    {
        ServletContext context=sce.getServletContext();
        String path=context.getRealPath("count.txt");
        java.io.File file=new java.io.File(path);
        if(!file.exists())
        {
            context.setAttribute("total",1000);
        }
        else
        {
            int total;
            try
            {
                DataInputStream dis=new DataInputStream(new FileInputStream(path));
                total = dis.readInt();
            } 
            catch (Exception ex)
            {
                ex.printStackTrace();
                total=0;
            }           
           context.setAttribute("total",total);
        }
        
        context.setAttribute("online",0);        
    }
    public void contextDestroyed(ServletContextEvent sce)
    {
        ServletContext context=sce.getServletContext();
        String path=context.getRealPath("count.txt");
        int total=Integer.parseInt(context.getAttribute("total").toString());
        try
        {            
            FileOutputStream fos=new FileOutputStream(path);      
            DataOutputStream dos=new DataOutputStream(fos);
            dos.writeInt(total);
            dos.close();
            fos.close();
        } 
        catch (Exception ex)
        {
            ex.printStackTrace();
        }
    }
    
}