【转】轮询、长轮询、iframe长连接、web socket

引自：http://www.cnblogs.com/AloneSword/p/3517463.html

http://www.cnblogs.com/wei2yi/archive/2011/03/23/1992830.html

代码示例：

1.iframe实现长连接

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>Insert title here</title>
</head>
<script type="text/javascript" src="jquery-1.9.1.js"></script>

<script>
    function loadData(){
        $('#logs').append(new Date());
    }
</script>
<body>
<iframe id="frame" name="polling" src="/myweb/TestLongPolling"></iframe>
        <div id="logs"></div>
</body>
</html>

package bookstore;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class TestLongPolling
 */
@WebServlet("/TestLongPolling")
public class TestLongPolling extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public TestLongPolling() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doPost(request,response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        int i = 0;  
        boolean boo = true;  
        String result = null;  
        while(boo){  
            try {  
                    Thread.sleep(1000);  
                } catch (InterruptedException e) {  
                    e.printStackTrace();    
                }  
            result = "hello I'm server"+i;//要打印到前台的字符  
            //sendMsg(result,response,"msg");//msg是test.jsp中的那个js方法的名称  
            
                response.setContentType("text/html;charset=GBK");  
                response.getWriter().write(  
                        "<script type='text/javascript'>parent.loadData()</script>");  
                response.flushBuffer();  
            
            i++;  
            if(i==10){  
                boo = false;  
            }  
        }  
    }

}

2.web socket

待续....

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原文地址：https://www.cnblogs.com/grape1211/p/4231631.html