首页 > 代码库 > DWR3实现服务器端向客户端精确推送消息
DWR3实现服务器端向客户端精确推送消息
原贴地址:http://blog.csdn.net/luojia_wang/article/details/8825929
研究了一天半,终于模拟出了这个功能,网上DWR的资料不少,但是真正实现客户端向服务器端精确推送消息的只有两篇文章。但是代码都只有一部分,向我这种刚开始学习DWR的人来说要看懂真的蛮难。不过即便如此,http://www.blogjava.net/stevenjohn/archive/2012/07/07/382447.html这片文章还是给了我很大帮助,再次表示感谢,下面我将这两天的研究详细记录下来备忘,也希望能帮助到像我一样的人。只写过程,不写原理(不是不写,而是有些地方我也不太懂),下面开始:
第一、在项目中引入dwr.jar,然后在web.xml中进行配置,配置如下:
- <servlet>
- <servlet-name>dwr-invoker</servlet-name>
- <servlet-class>
- org.directwebremoting.servlet.DwrServlet
- </servlet-class>
- <init-param>
- <param-name>crossDomainSessionSecurity</param-name>
- <param-value>false</param-value>
- </init-param>
- <init-param>
- <param-name>allowScriptTagRemoting</param-name>
- <param-value>true</param-value>
- </init-param>
- <init-param>
- <param-name>classes</param-name>
- <param-value>java.lang.Object</param-value>
- </init-param>
- <init-param>
- <param-name>activeReverseAjaxEnabled</param-name>
- <param-value>true</param-value>
- </init-param>
- <init-param>
- <param-name>initApplicationScopeCreatorsAtStartup</param-name>
- <param-value>true</param-value>
- </init-param>
- <init-param>
- <param-name>maxWaitAfterWrite</param-name>
- <param-value>3000</param-value>
- </init-param>
- <init-param>
- <param-name>debug</param-name>
- <param-value>true</param-value>
- </init-param>
- <init-param>
- <param-name>logLevel</param-name>
- <param-value>WARN</param-value>
- </init-param>
- </servlet>
第二:在web.xml的同级目录下新建dwr.xml文件,内容如下
- <!DOCTYPE dwr PUBLIC
- "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN"
- "http://getahead.org/dwr/dwr30.dtd">
- <dwr>
- <alow>
- <create creator="new" javascript="MessagePush">
- <param name="class" value=http://www.mamicode.com/"com.huatech.messageremind.service.MessagePush"/>
- </create>
- <create creator="new" javascript="TestPush">
- <param name="class" value=http://www.mamicode.com/"com.huatech.messageremind.service.Test"/>
- </create>
- </alow>
- </dwr>
这个是dwr的基本配置,MessagePush在页面的javascript中使用,这个是对被推送页面开放的java类,Test是对推送页面开放的java类。场景:管理员后台登陆,发布一条消息,通过Test推送到后台,后台通过MessagePush推送给指定的用户,当然,至于怎么找到指定的用户,下面会说。
第三,被推送的页面代码
- <%@ 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=http://www.mamicode.com/"<%=basePath%>">
- <title>DWR DEMO</title>
- <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">
- </head>
- <script type=‘text/javascript‘ src=http://www.mamicode.com/‘dwr/engine.js‘></script>
- <script type=‘text/javascript‘ src=http://www.mamicode.com/‘dwr/util.js‘></script>
- <script type="text/javascript" src=http://www.mamicode.com/"dwr/interface/MessagePush.js"></script>
- <script type="text/javascript">
- //通过该方法与后台交互,确保推送时能找到指定用户
- function onPageLoad(){
- var userId = ‘${userinfo.humanid}‘;
- MessagePush.onPageLoad(userId);
- }
- //推送信息
- function showMessage(autoMessage){
- alert(autoMessage);
- }
- </script>
- <body onload="onPageLoad();dwr.engine.setActiveReverseAjax(true);dwr.engine.setNotifyServerOnPageUnload(true);;">
- This is my DWR DEOM page. <hr>
- <br>
- <div id="DemoDiv">demo</div>
- </body>
- </html>
以上代码的简单解释:
页面页面onload的3个函数都是必须的,后两个是dwr的,第一个是将登录用户的userid与对应 的scriptSession进行处理,以便精确推送的时候能找到推送对象
第四 MessagePush类中实现的方法如下:
- public void onPageLoad(String userId) {
- ScriptSession scriptSession = WebContextFactory.get().getScriptSession();
- scriptSession.setAttribute(userId, userId);
- DwrScriptSessionManagerUtil dwrScriptSessionManagerUtil = new DwrScriptSessionManagerUtil();
- try {
- dwrScriptSessionManagerUtil.init();
- System.out.println("cacaca");
- } catch (ServletException e) {
- e.printStackTrace();
- }
- }
里面对应的DwrScriptSessionManagerUtil 对应如下:
- import javax.servlet.ServletException;
- import javax.servlet.http.HttpSession;
- import org.directwebremoting.Container;
- import org.directwebremoting.ServerContextFactory;
- import org.directwebremoting.WebContextFactory;
- import org.directwebremoting.event.ScriptSessionEvent;
- import org.directwebremoting.event.ScriptSessionListener;
- import org.directwebremoting.extend.ScriptSessionManager;
- import org.directwebremoting.servlet.DwrServlet;
- public class DwrScriptSessionManagerUtil extends DwrServlet{
- private static final long serialVersionUID = -7504612622407420071L;
- public void init()throws ServletException {
- Container container = ServerContextFactory.get().getContainer();
- ScriptSessionManager manager = container.getBean(ScriptSessionManager.class);
- ScriptSessionListener listener = new ScriptSessionListener() {
- public void sessionCreated(ScriptSessionEvent ev) {
- HttpSession session = WebContextFactory.get().getSession();
- String userId =((User) session.getAttribute("userinfo")).getHumanid()+"";
- System.out.println("a ScriptSession is created!");
- ev.getSession().setAttribute("userId", userId);
- }
- public void sessionDestroyed(ScriptSessionEvent ev) {
- System.out.println("a ScriptSession is distroyed");
- }
- };
- manager.addScriptSessionListener(listener);
- }
- }
第五 推送页面代码:
- <%@ 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=http://www.mamicode.com/"<%=basePath%>">
- <title>My JSP ‘MyJsp.jsp‘ starting page</title>
- <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">
- <script type="text/javascript" src=http://www.mamicode.com/"<%=request.getContextPath() %>/js/jquery-1.5.1.js"></script>
- <script type=‘text/javascript‘ src=http://www.mamicode.com/‘dwr/engine.js‘></script>
- <script type=‘text/javascript‘ src=http://www.mamicode.com/‘dwr/util.js‘></script>
- <script type=‘text/javascript‘ src=http://www.mamicode.com/‘dwr/interface/TestPush.js‘></script>
- <script type="text/javascript">
- function test() {
- var msg = document.getElementById("msgId").value;
- //msg = {msgId: ‘1‘, context: $("#msgContext").val()};
- TestPush.sendMessageAuto(msg,"哈哈哈");
- }
- </script>
- </head>
- <body>
- id : <input type="text" name="msgId" id="msgId" /> <br />
- <input type="button" value=http://www.mamicode.com/"Send" onclick="test()" />
- </body>
- </html>
第六:精确推送要实现的代码:
- public class Test{
- public void sendMessageAuto(String userid, String message){
- final String userId = userid;
- final String autoMessage = message;
- Browser.withAllSessionsFiltered(new ScriptSessionFilter() {
- public boolean match(ScriptSession session){
- if (session.getAttribute("userId") == null)
- return false;
- else
- return (session.getAttribute("userId")).equals(userId);
- }
- }, new Runnable(){
- private ScriptBuffer script = new ScriptBuffer();
- public void run(){
- script.appendCall("showMessage", autoMessage);
- Collection<ScriptSession> sessions = Browser
- .getTargetSessions();
- for (ScriptSession scriptSession : sessions){
- scriptSession.addScript(script);
- }
- }
- });
- }
- }
至此 这个例子的代码都已经贴出来了,应该是可以跑通的,有问题的话可以给我留言。当然,要自己写个登录,然后把userId放到session里面,这个比较简单,就不贴代码了,有问题可以在http://download.csdn.net/detail/luojia_wang/5275588上下载原项目。我只是简单的做了一个能实现功能的例子,还有很多地方要研究,比如跟spring整合,还可能有很多优化,等我继续学习一下再说.
DWR3实现服务器端向客户端精确推送消息