persona5 攻略女生:基于AJAX的长轮询（long-polling）方式实现简单的聊天室程序

这里只是做个测试，很简单，没有做好线程同步的问题，只是为了长轮询。原理：可以看:http://yiminghe.javaeye.com/blog/294781AJAX 的出现使得 JavaScript 可以调用 XMLHttpRequest 对象发出 HTTP 请求，JavaScript 响应处理函数根据服务器返回的信息对 HTML 页面的显示进行更新。使用 AJAX 实现“服务器推”与传统的 AJAX 应用不同之处在于： 服务器端会阻塞请求直到有数据传递或超时才返回。
客户端 JavaScript 响应处理函数会在处理完服务器返回的信息后，再次发出请求，重新建立连接。
当客户端处理接收的数据、重新建立连接时，服务器端可能有新的数据到达；这些信息会被服务器端保存直到客户端重新建立连接，客户端会一次把当前服务器端所有的信息取回。
聊天页面的代码：view plaincopy to clipboardprint?
<%@ page language="java" pageEncoding="GBK"%> 
 
 
     
         
         
         
         
         
         
         
         
                    src="ext-2.2/build/locale/ext-lang-zh_CN.js"> 
         
     
     
         
        username:  
         
       
 
        message:  
         
       
 
         
     
 
<%@ page language="java" pageEncoding="GBK"%>


 
  
  
  
  
  
  
  
  
     src="ext-2.2/build/locale/ext-lang-zh_CN.js">
  
 
 
  
  username:
  
  

  message:
  
  

  
 

 定义mm.js，定义发送消息，定义接收消息的JS函数view plaincopy to clipboardprint?
Ext.onReady(function () {  
    getMsg();  
});  
function getMsg() {  
    Ext.Ajax.request({url:"getMsg", callback:function (options, success, response) {  
        if (success) {  
            Ext.DomHelper.append(Ext.get("main"), response.responseText, true);  
        }  
        getMsg();  
    }});  
}  
function putMsg() {  
    Ext.Ajax.request({url:"putMsg", params:{message:document.getElementById("message").value}});  
}  
/* 
Ext.Updater.defaults.indicatorText=''; 
    var updater = Ext.get('main').getUpdater(); 
    updater.update({ 
        url:"getMsg" 
    }); 
*/ 
Ext.onReady(function () {
 getMsg();
});
function getMsg() {
 Ext.Ajax.request({url:"getMsg", callback:function (options, success, response) {
  if (success) {
   Ext.DomHelper.append(Ext.get("main"), response.responseText, true);
  }
  getMsg();
 }});
}
function putMsg() {
 Ext.Ajax.request({url:"putMsg", params:{message:document.getElementById("message").value}});
}
/*
Ext.Updater.defaults.indicatorText='';
 var updater = Ext.get('main').getUpdater();
 updater.update({
  url:"getMsg"
 });
*/  下面是获得message的servletview plaincopy to clipboardprint?
package hyjc.listener;  
 
import java.io.IOException;  
import java.io.PrintWriter;  
 
import javax.servlet.ServletException;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
 
public class GetMsg extends HttpServlet {  
 
    public void doGet(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
 
        response.setContentType("text/html");  
        PrintWriter out = response.getWriter();  
        MessageList m = MessageList.getInstance();  
        boolean end = false;  
        while (!end) {  
            System.out.println("before get");  
            String msg = m.get();  
            System.out.println("after get " + msg);  
            out.write(msg + "
");  
            if (m.isEmpty()) {  
                end = true;  
            }  
        }  
        out.close();  
    }  
 
    public void doPost(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
        doGet(request, response);  
    }  
 
} 
package hyjc.listener;import java.io.IOException;
import java.io.PrintWriter;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class GetMsg extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {  response.setContentType("text/html");
  PrintWriter out = response.getWriter();
  MessageList m = MessageList.getInstance();
  boolean end = false;
  while (!end) {
   System.out.println("before get");
   String msg = m.get();
   System.out.println("after get " + msg);
   out.write(msg + "
");
   if (m.isEmpty()) {
    end = true;
   }
  }
  out.close();
 } public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  doGet(request, response);
 }}
 下面是添加消息的servletview plaincopy to clipboardprint?
package hyjc.listener;  
 
import java.io.IOException;  
import java.io.PrintWriter;  
 
import javax.servlet.ServletException;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
 
public class PutMsg extends HttpServlet {  
 
    public void doGet(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
 
        response.setContentType("text/html");  
        System.out.println("put message");  
        PrintWriter out = response.getWriter();  
        out.flush();  
        String msg = request.getParameter("message");  
        if (null != msg) {  
            MessageList.getInstance().add(msg);  
        } else {  
            System.out.println("添加消息:" + msg + "成果");  
        }  
        out.close();  
    }  
 
    public void doPost(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
        doGet(request, response);  
    }  
 
} 
package hyjc.listener;import java.io.IOException;
import java.io.PrintWriter;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class PutMsg extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {  response.setContentType("text/html");
  System.out.println("put message");
  PrintWriter out = response.getWriter();
  out.flush();
  String msg = request.getParameter("message");
  if (null != msg) {
   MessageList.getInstance().add(msg);
  } else {
   System.out.println("添加消息:" + msg + "成果");
  }
  out.close();
 } public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  doGet(request, response);
 }}
 下面是存放消息的消息队列，内部用阻塞队列使用view plaincopy to clipboardprint?
package hyjc.listener;  
 
import java.util.Iterator;  
import java.util.concurrent.LinkedBlockingQueue;  
 
public class MessageList {  
 
    private static MessageList list = null;  
 
    private static Object key = new Object();  
 
    private MessageList() {  
        this.add("hello");  
        this.add("world");  
    }  
 
    public static MessageList getInstance() {  
        synchronized (key) {  
            if (list == null) {  
                list = new MessageList();  
            }  
            return list;  
        }  
    }  
 
    private LinkedBlockingQueue queue = new LinkedBlockingQueue();  
 
    public boolean isEmpty() {  
        return queue.isEmpty();  
    }  
 
    public int size() {  
        return queue.size();  
    }  
 
    public String get() {  
        try {  
            return queue.take();  
        } catch (InterruptedException e) {  
            e.printStackTrace();  
            return null;  
        }  
    }  
 
    public void clear() {  
        queue.clear();  
    }  
 
    public void add(String msg) {  
        try {  
            queue.put(msg);  
        } catch (InterruptedException e) {  
            e.printStackTrace();  
        }  
    }  
 
    public Iterator iterator() {  
        return queue.iterator();  
    }  
} 
package hyjc.listener;import java.util.Iterator;
import java.util.concurrent.LinkedBlockingQueue;public class MessageList { private static MessageList list = null; private static Object key = new Object(); private MessageList() {
  this.add("hello");
  this.add("world");
 } public static MessageList getInstance() {
  synchronized (key) {
   if (list == null) {
    list = new MessageList();
   }
   return list;
  }
 } private LinkedBlockingQueue queue = new LinkedBlockingQueue(); public boolean isEmpty() {
  return queue.isEmpty();
 } public int size() {
  return queue.size();
 } public String get() {
  try {
   return queue.take();
  } catch (InterruptedException e) {
   e.printStackTrace();
   return null;
  }
 } public void clear() {
  queue.clear();
 } public void add(String msg) {
  try {
   queue.put(msg);
  } catch (InterruptedException e) {
   e.printStackTrace();
  }
 } public Iterator iterator() {
  return queue.iterator();
 }
}
 下面是演示效果，输入message，点击submit，就会添加到MessageList中，然后会在GetMsg中继续执行，实现长连接  本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/neusoftware_20063500/archive/2009/04/30/4140903.aspx本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/neusoftware_20063500/archive/2009/04/30/4140903.aspx