DWR第三篇之逆向Ajax升级

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/