一个关于dwr实现服务器推技术的问题求解

发布于 2021-12-02 02:33:47 字数 6770 浏览 884 评论 3

我想实现一个客户端登陆后然后服务器主动给客户端发消息的功能但是消息死活推不过去
代码如下

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>

    <!-- 把Web应用根目录以属性名添加到系统参数中 -->
    <listener>
        <listener-class>
            org.directwebremoting.servlet.DwrListener
        </listener-class>
    </listener>

    <servlet>
        <servlet-name>dwr-invoker</servlet-name>
        <servlet-class>
            org.directwebremoting.servlet.DwrServlet
        </servlet-class>
        <init-param>
            <param-name>pollAndCometEnabled</param-name>
            <param-value>true</param-value>
        </init-param>
        <init-param>
            <param-name>activeReverseAjaxEnabled</param-name>
            <param-value>true</param-value>
        </init-param>
        <init-param>
            <!-- dwr配置文件路径 -->
            <param-name>config</param-name>
            <param-value>/WEB-INF/dwr.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet>
        <servlet-name>LoginServlet</servlet-name>
        <servlet-class>com.msg.web.LoginServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>dwr-invoker</servlet-name>
        <url-pattern>/dwr/*</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>LoginServlet</servlet-name>
        <url-pattern>/LoginServlet</url-pattern>
    </servlet-mapping>

</web-app>

dwr.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 1.0//EN" "http://www.getahead.ltd.uk/dwr/dwr10.dtd">
<dwr>
    <allow>
        <!-- chat -->
        <create creator="new" javascript="MsgService">
            <param name="class" value="com.msg.service.MsgService" />
        </create>
    </allow>

</dwr>

MsgService.java

package com.msg.service;

import org.directwebremoting.Browser;
import org.directwebremoting.ServerContextFactory;
import org.directwebremoting.ui.dwr.Util;

public class MsgService {
    
    public void sendMsg(final String msg) {
        // 向指定页面推送消息
        Browser.withPage(ServerContextFactory.get().getContextPath()+"/client.jsp",new Runnable() {
            public void run() {
                Util.setValue("msgBox", msg);
            }
        });
    }

}

client.jsp

<%@ 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%>">

        <meta http-equiv="pragma" content="no-cache">
        <meta http-equiv="cache-control" content="no-cache">
        <meta http-equiv="expires" content="0">
        <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
        <meta http-equiv="description" content="This is my page">
        <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
        <script type='text/javascript' src='dwr/engine.js'></script>
          <script type='text/javascript' src='dwr/interface/MsgService.js'></script>
          <script type='text/javascript' src='dwr/util.js'></script>
    </head>

    <body onload="dwr.engine.setActiveReverseAjax(true);">
        <br>
        <br/>
        <div align="center">
        <span>当前登录用户名:</span>${userName}
        <p>
            Server Message:
        </p>
        <hr />
        </div>
        <div id="msgBox"></div>
    </body>
</html>

server.jsp

<%@ 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%>">

        <meta http-equiv="pragma" content="no-cache">
        <meta http-equiv="cache-control" content="no-cache">
        <meta http-equiv="expires" content="0">
        <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
        <meta http-equiv="description" content="This is my page">
        <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
        <script type='text/javascript' src='dwr/engine.js'></script>
          <script type='text/javascript' src='dwr/interface/MsgService.js'></script>
          <script type='text/javascript' src='dwr/util.js'></script>
          
        <script type="text/javascript">
            dwr.engine.setActiveReverseAjax(true);
            function sendMessage(){
                var message = dwr.util.getValue("msg");
                MsgService.sendMsg(message);
            }
        </script>
    </head>

    <body>
        <br>
        <br/>
        <div align="center">
        <p>
            Your Message:
            <input id="msg"  />
            <input type="button" value="Send" onclick="sendMessage()" />
        </p>
        </div>
    </body>
</html>

这是大部分实现代码实在不明白为什么推不出去了希望做过这方面的大神提示一下下

感谢

另外我用 Browser.withCurrentPage() 实现了客户端直接的信息传递即聊天室功能
但是服务器主动给客户端发送信息死活不行。。。

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