使用DWR框架实现服务器推送Demo

1、新建web项目

2、导入jar包（commons-logging-1.2.jar、dwr3.0.jar）

3、配置web.xml，并在web.xml同目录下创建dwr.xml

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">
  <display-name></display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
<servlet>  
        <servlet-name> dwr-invoker </servlet-name>  
        <servlet-class> uk.ltd.getahead.dwr.DWRServlet</servlet-class > 
        <init-param>  
            <param-name> debug</param-name > 
            <param-value> true</param-value >
        </init-param>
        <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>activeReverseAjaxEnabled</param-name>
<param-value>true</param-value>
</init-param>
</servlet> 
<servlet-mapping>  
        <servlet-name> dwr-invoker </servlet-name>  
        <url-pattern>/dwr/*</url-pattern> 
</servlet-mapping>
</web-app>

dwr.xml：

<?xml version="1.0" encoding= "UTF-8"?> 
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN" "http://getahead.org/dwr/dwr30.dtd" > 
<dwr>  
        <allow>  
               <create creator="new" javascript= "messagePush"> 
                      <param name="class" >sugar.dwr.MessagePush</param> 
               </create>
        </allow>  
</dwr>

4、编写java类

package sugar.dwr;
/**
 * 本节Demo实现的基本功能：
 * 在之前的的代码基础上修改，
 * 实现将index.jsp输入框中的推送文本显示在其它打开的jsp页面上
 * 目前流行的服务器推送技术
 */
import java.util.Collection;
import org.directwebremoting.Browser;
import org.directwebremoting.ScriptBuffer;
import org.directwebremoting.ScriptSession;

public class MessagePush {

        public void send(final String content){

              Runnable run = new Runnable(){
                      private ScriptBuffer script = new ScriptBuffer();
                      public void run() {
                            //设置要调用的 js及参数
                            script.appendCall("show" , content);
                            //得到所有ScriptSession
                           Collection<ScriptSession> sessions = Browser.getTargetSessions();
                            //遍历每一个ScriptSession
                            for (ScriptSession scriptSession : sessions){
                                  scriptSession.addScript( script);
                           }
                     }
              };
               //执行推送
              Browser. withAllSessions(run);
       }
}

5、编写页面

index.xml：

<%@ page language= "java" import ="java.util.*" pageEncoding="UTF-8" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head >
    <title >DWR</title>
    <script src="http://libs.baidu.com/jquery/1.8.3/jquery.min.js"></script>
    <script type= "text/javascript" src ="dwr/util.js"></script>   
        <script type="text/javascript" src= "dwr/engine.js"></script > 
        <script type="text/javascript" src= "dwr/interface/messagePush.js" ></script>
  </head >
  <body >
        <table border="0" >
               <tr>
                      <td><input id ="content" type="text"/></td>
                      <td><input id ="send" type="button" value= "send"/></td >
               </tr>
        </table>
        <script type="text/javascript" >
              $( "#send").click(function(){
                      var content = $("#content" ).val();
                     messagePush.send(content);
              });
        </script>
  </body >
</html>

receiver.xml：

<%@ page language= "java" import ="java.util.*" pageEncoding="UTF-8" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head >
    <title>dwr接收</title >
        <script src="http://libs.baidu.com/jquery/1.8.3/jquery.min.js"></script>
        <script type="text/javascript" src= "dwr/util.js"></script >   
        <script type="text/javascript" src= "dwr/engine.js"></script >
        <script type="text/javascript" src= "dwr/interface/messagePush.js" ></script>
  </head >

  <body>dwr接收<br/>
        <div id="content" style=" width: 200px ;height: 30px;border : 1px solid ; text-align: center ; padding: 5px;"></div>
        <script type="text/javascript" >
           //这个方法用来启动该页面的ReverseAjax功能
           dwr.engine.setActiveReverseAjax(true);
           //设置在页面关闭时，通知服务端销毁会话
           dwr.engine.setNotifyServerOnPageUnload(true);
           //这个函数是提供给后台推送的时候 调用的
           function show(content){ 
               $( "#content" ).text(content);
           }
        </script>
  </body >
</html>

运行项目，先打开http://******:8080/ServerPush/receiver.jsp

然后在index.xml中输入发送的内容，即可发送并显示到receiver.jsp页面上。

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使用DWR框架实现服务器推送Demo

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