DWR第三篇之逆向Ajax升级

时间：2022-05-10 00:39:04

1. 本示例在第二篇架构基础上添加代码

2.在client.jsp开头的地方添加如下代码：

本示例需要做的是定向推送，那么就需要浏览器进行登录，从而进行定向的推送功能，为了节省时间，这里不做登录模块了，在url后拼接一个参数作为登录标识。

 <%

     String id = request.getParameter("id");

     session.setAttribute("id", id);

 %>

这样，在登录的时候在url后边拼接id=xxx，就可以模拟登录功能，并将登陆信息存在session中。

3. 此外，client.jsp中还要添加如下代码（修改原来的地方）

 <script type="text/javascript">

     window.onload = function() {

         //开启逆向Ajax功能

         dwr.engine.setActiveReverseAjax(true);

         //开启关闭页面提醒服务器功能

         dwr.engine.setNotifyServerOnPageUnload(true);

         //对当前用户进行注册

         CoreServlet.regist();

     }

 </script>

4. 修改index.jsp内容：

 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

 <%

     String path = request.getContextPath();

     String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";

 %>

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

 <html>

 <head>

 <base href="<%=basePath%>">

 <title>dwr_demo</title>

 <script type='text/javascript' src='dwr/engine.js'></script>

 <script type='text/javascript' src='dwr/util.js'></script>

 <script type='text/javascript' src='dwr/interface/CoreServlet.js'></script>

 </head>

 <body>

     <input type="button" value="发送" onclick="sayHello();">

     <br>

     <input type="text" id="getHello">

     <input type="button" value="发送" onclick="getHello();">

     <input type="text" id="getHelloValue">

     <br>

     <input type="text" id="sendMsg">

     <input type="button" value="推送" onclick="sendMsg();">

     <br>

     发送目标：<input type="text" id="target">

     发送内容：<input type="text" id="msg">

     <input type="button" value="发送" onclick="directionalSendMsg();">

 </body>

 <script type="text/javascript">

     function sayHello() {

         CoreServlet.sayHello();

     }

     function getHello() {

         var name = dwr.util.getValue("getHello");

         CoreServlet.getHello(name, function(data) {

             dwr.util.setValue("getHelloValue", data);

         });

     }

     function sendMsg() {

         var msg = dwr.util.getValue("sendMsg");

         CoreServlet.send(msg);

     }

     function directionalSendMsg() {

         var target = dwr.util.getValue("target");

         var msg = dwr.util.getValue("msg");

         CoreServlet.directionalSendMsg(target + ":" + msg);

     }

 </script>

 </html>

5. 在CoreServlet.java里添加两个方法

 /**

 * 定向推送消息

 */

 public void directionalSendMsg(String msg) {

     final String[] param = msg.split(":");

     Browser.withAllSessionsFiltered(new ScriptSessionFilter() {

         @Override

         public boolean match(ScriptSession session) {

             boolean flag = param[0].equals(session.getAttribute("key"));

             return flag;

         }

     }, new Runnable() {

         @Override

         public void run() {

             Util.setValue("msg", param[1]);

         }

     });

 }

 /**

  * 用户注册

  */

 public void regist() {

     // 获取当前的scriptSession

     ScriptSession scriptSession = WebContextFactory.get().getScriptSession();

     // 获取HttpSession 并获得其中的userId

     HttpSession session = WebContextFactory.get().getSession();

     String id = (String) session.getAttribute("id");

     // 对当前scriptSession的key设置指定的值

     scriptSession.setAttribute("key", id);

 }

6. 开三个窗口进行测试:

http://localhost:8080/dwr_demo/client.jsp?id=zhangsan
http://localhost:8080/dwr_demo/client.jsp?id=lisi
http://localhost:8080/dwr_demo/

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