servlet3.0

servlet3.0 反向ajax的操作模板

1.servlet

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Queue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
 *
 * @author Administrator
 */
@WebServlet(name = "ChatRoom", urlPatterns = {"/ChatRoom"},asyncSupported=true)
public class ChatRoom extends HttpServlet {
    //在并发链接队列中存放异步交互上下文
    private static final Queue<AsyncContext> queue=new ConcurrentLinkedQueue<AsyncContext>();
    //在阻塞队列中存放消息(链接阻塞队列)
    private static final BlockingQueue<String> messageQueue=new LinkedBlockingQueue<String>();
    //javascript 发送至iframe中
    private static final String BEGIN_SCRIPT_TAG = "<script type='text/javascript'>\n";
    private static final String END_SCRIPT_TAG = "</script>\n";
    private Thread notifierThread=null;
    @Override
    public void init(ServletConfig config) throws ServletException {
    Runnable notifierRunnable=new Runnable() {
            @Override
            public void run() {
            boolean done = false;
                while (!done) {
                    String cMessage = null;
                    try {
                        cMessage = messageQueue.take();
                        for (AsyncContext ac : queue) {
                            try {
                                PrintWriter acWriter = ac.getResponse().getWriter();
                                acWriter.println(cMessage);
                                acWriter.flush();
                            } catch(IOException ex) {
                                System.out.println(ex);
                                queue.remove(ac);
                            }
                        }
                    } catch(InterruptedException iex) {
                        done = true;
                        System.out.println(iex);
                    }
                }
            }
        };
        notifierThread = new Thread(notifierRunnable);
        notifierThread.start();            
    }
    
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html");
        response.setHeader("Cache-Control", "private");
        response.setHeader("Pragma", "no-cache");        
         final AsyncContext ac = request.startAsync();
        ac.setTimeout(10  * 60 * 1000);
        ac.addListener(new AsyncListener() {
            @Override
            public void onComplete(AsyncEvent event) throws IOException {
                queue.remove(ac);
            }

            @Override
            public void onTimeout(AsyncEvent event) throws IOException {
                queue.remove(ac);
            }
            @Override
            public void onError(AsyncEvent event) throws IOException {
                queue.remove(ac);
            }
            @Override
            public void onStartAsync(AsyncEvent event) throws IOException {
            }
        });
        queue.add(ac);
    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        try {
            response.setContentType("text/html;charset=UTF-8");
            response.setHeader("Cache-Control", "private");
            request.setCharacterEncoding("UTF-8");                
            String name=request.getParameter("name");
            String script="window.parent.alert('"+name+"')";
            String cMessage=BEGIN_SCRIPT_TAG+script +END_SCRIPT_TAG;      
            messageQueue.put(cMessage);
        } catch (InterruptedException ex) {
            Logger.getLogger(ChatRoom.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    @Override
    public void destroy() {
      queue.clear();
      notifierThread.interrupt();
    }   
}

2.html

 <!DOCTYPE html>
<html>
    <head>
        <title></title>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <script type="text/javascript" src="js/jquery-1.7.min.js"></script>
        <script type="text/javascript" src="js/application.js"></script> 
      
    </head>
    <body >
        <div id="form">
            <label>输入姓名</label>
            <input type="text"/>
            <input type="button" value="提交"/>
        </div>
        <iframe id="comet-frame" style="display: none;"></iframe>   
    </body>
</html>

3.javascript
application.js 使用了jquery1.7

var app={
    post:function(){
     $.post("ChatRoom", {name:$("#form input[type='text']").val()},"html")         
    }
}
$(document).ready(function() { 
     var count=0;
     var url = 'ChatRoom'+'?'+count; 
     $('#comet-frame').attr("src", url)
     count++;
     $("#form input[type='button']").click(function(){
         app.post();
     })
 });