用DWR comet+Spring实现服务器推送的例子--网页聊天室

最近网上看的代码 敲下来试试 行得通 于是拿到这里和大家分享下。

首先 下载DWR的JAR包 下载地址http://directwebremoting.org/dwr/downloads/index.html

接下来 在web工程中加入相应的jar包，因为用到了spring的消息驱动机制 如下:

Message.java

import java.util.Date;  
/** 
 * 作为信息传递的基础类 
 * @author frank59 
 * 
 */  
public class Message {  
    private int id;  
    private String msg;  
    private Date time;  
    public int getId() {  
        return id;  
    }  
    public void setId(int id) {  
        this.id = id;  
    }  
    public String getMsg() {  
        return msg;  
    }  
    public void setMsg(String msg) {  
        this.msg = msg;  
    }  
    public Date getTime() {  
        return time;  
    }  
    public void setTime(Date time) {  
        this.time = time;  
    }  
}  

ChatMessageEvent.java

import org.springframework.context.ApplicationEvent;  
/** 
 * 自定义事件类 
 * @author frank59 
 * 
 */  
public class ChatMessageEvent extends ApplicationEvent{  
  
    public ChatMessageEvent(Object source) {  
        super(source);  
    }  
    private static final long serialVersionUID = -6626763488290315190L;  
}  

ChatMessageClient.java

import java.util.Collection;  
import java.util.Date;  
import javax.servlet.ServletContext;  
import org.directwebremoting.ScriptBuffer;  
import org.directwebremoting.ScriptSession;  
import org.directwebremoting.ServerContext;  
import org.directwebremoting.ServerContextFactory;  
import org.springframework.context.ApplicationEvent;  
import org.springframework.context.ApplicationListener;  
import org.springframework.web.context.ServletContextAware;  
  
import entity.Message;  
/** 
 * MessageEvent事件的监听类 
 * 需要spring的支持 利用spring的消息驱动机制 
 * @author frank59 
 * 
 */  
@SuppressWarnings("unchecked")  
public class ChatMessageClient implements ApplicationListener,  
        ServletContextAware {  
    private ServletContext ctx;  
  
    @SuppressWarnings("deprecation")  
    public void onApplicationEvent(ApplicationEvent event) {  
        // 如果事件类型是ChatMessageEvent就执行下面操作  
        if (event instanceof ChatMessageEvent) {  
            Message msg = (Message) event.getSource();  
            ServerContext context = ServerContextFactory.get();  
            // 获得客户端所有chat页面script session连接数  
            Collection<ScriptSession> sessions = context  
                    .getScriptSessionsByPage(ctx.getContextPath() + "/chat.jsp");  
            for (ScriptSession session : sessions) {  
                ScriptBuffer sb = new ScriptBuffer();  
                Date time = msg.getTime();  
                String s = time.getYear() + "-" + (time.getMonth() + 1) + "-"  
                        + time.getDate() + " " + time.getHours() + ":"  
                        + time.getMinutes() + ":" + time.getSeconds();  
                System.out.println(s);/////////////////s  
                // 执行setMessage方法  
                sb.appendScript("showMessage({msg: '").appendScript(  
                        msg.getMsg()).appendScript("', time: '")  
                        .appendScript(s).appendScript("'})");  
                System.out.println(sb.toString());/////////////////sb  
                //执行客户端script session方法，相当于浏览器执行JavaScript代码                     
                //上面就会执行客户端浏览器中的showMessage方法，并且传递一个对象过去    
                session.addScript(sb);  
            }  
        }  
    }  
    public void setServletContext(ServletContext arg0) {  
        this.ctx = arg0;  
    }  
}  

ChatService.java

实现 ApplicationContextAware 接口 ，新增ChatMessageEvent 并 publishEvent

applicationContext-beans.xml

<?xml version="1.0" encoding="UTF-8"?>  
<beans xmlns="http://www.springframework.org/schema/beans"  
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"  
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:util="http://www.springframework.org/schema/util"  
    xmlns:context="http://www.springframework.org/schema/context"  
    xsi:schemaLocation="http://www.springframework.org/schema/beans   
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd   
    http://www.springframework.org/schema/aop         
    http://www.springframework.org/schema/aop/spring-aop-3.0.xsd        
    http://www.springframework.org/schema/tx         
    http://www.springframework.org/schema/tx/spring-tx-3.0.xsd        
    http://www.springframework.org/schema/util         
    http://www.springframework.org/schema/util/spring-util-3.0.xsd        
    http://www.springframework.org/schema/context         
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">  
    <bean id="chatService" class="chat.ChatService"/>   
    <bean id="chatMessageClient" class="chat.ChatMessageClient"/>  
</beans>  

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>  
        <convert match="entity.Message" converter="bean">  
            <param name="include" value="msg,time" />  
        </convert>  
        <create creator="spring" javascript="ChatService">  
            <param name="beanName" value="chatService" />  
        </create>  
    </allow>  
</dwr>  

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">  
    <!-- 加载Spring容器配置 -->  
    <listener>  
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>  
    </listener>  
    <!-- 设置Spring容器加载配置文件路径 -->  
    <context-param>  
        <param-name>contextConfigLocation</param-name>  
        <param-value>classpath*:applicationContext-*.xml</param-value>  
    </context-param>  
    <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>debug</param-name>  
            <param-value>true</param-value>  
        </init-param>  
        <!-- dwr的comet控制 -->  
        <init-param>  
            <param-name>pollAndCometEnabled</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>  
    <welcome-file-list>  
        <welcome-file>index.jsp</welcome-file>  
    </welcome-file-list>  
</web-app> 

chat.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%>">  
  
        <title>My JSP 'chat.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">  
        <!-- 
    <link rel="stylesheet" type="text/css" href="styles.css"> 
    -->  
        <script type="text/javascript"  
            src="${pageContext.request.contextPath }/dwr/engine.js"></script>  
        <script type="text/javascript"  
            src="${pageContext.request.contextPath }/dwr/util.js"></script>  
        <script type="text/javascript"  
            src="${pageContext.request.contextPath }/dwr/interface/ChatService.js"></script>  
        <script type="text/javascript">           
            function send() {                
                var time = new Date();                
                var content = dwr.util.getValue("content");                
                var name = dwr.util.getValue("userName");                
                var info = encodeURI(encodeURI(name + " say:\n" + content));                
                var msg = {"msg": info, "time": time};                
                dwr.util.setValue("content", "");                
                if (!!content) {                    
                    ChatService.sendMessage(msg);                
                } else {                    
                    alert("发送的内容不能为空！");                
                }            
            }               
            function showMessage(data) {                
                var message = decodeURI(decodeURI(data.msg));                
                var text = dwr.util.getValue("info");                
                if (!!text) {                      
                    dwr.util.setValue("info", text + "\n" + data.time + "  " + message);                
                } else {                    
                    dwr.util.setValue("info", data.time + "  " + message);                
                }            
            }        
        </script>  
    </head>  
  
    <body onload="dwr.engine.setActiveReverseAjax(true);">  
        <textarea rows="20" cols="60" id="info" readonly="readonly"></textarea>  
        <hr />  
        昵称：<input type="text" id="userName" />  
        <br />  
        消息：<textarea rows="5" cols="30" id="content"></textarea>  
        <input type="button" value=" Send " onclick="send()" style="height: 85px; width: 85px;" />  
    </body>  
</html>