用DWR comet+Spring实现服务器推送的例子--网页聊天室

小灰灰 2021-05-12 11:51 374阅读 0赞

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][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:

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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">  
          
        <listener>  
            <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>  
        </listener>  
          
        <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>  
              
            <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">  
              
            <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 οnlοad="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 " οnclick="send()" style="height: 85px; width: 85px;" />  
        </body>  
    </html>

[http_directwebremoting.org_dwr_downloads_index.html]: http://directwebremoting.org/dwr/downloads/index.html
[Center]: /images/20210511/cbf6a865b347496f9ddc7e450104bdee.png
[Center 1]: /images/20210511/9824d8b77c6c4ef791d0451ba08effd1.png