DWR3使用

- 日理万妓 2023-10-16 22:48 58阅读 0赞

导入官方demo里面的jar包

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新建DWRScriptSessionListener

package com.dwr.test;
    
    import java.util.Collection;
    import java.util.HashMap;
    import java.util.Map;
    
    import javax.servlet.http.HttpSession;
    
    import org.directwebremoting.ScriptSession;
    import org.directwebremoting.WebContext;
    import org.directwebremoting.WebContextFactory;
    import org.directwebremoting.event.ScriptSessionEvent;
    import org.directwebremoting.event.ScriptSessionListener;
    
    public class DWRScriptSessionListener implements ScriptSessionListener {
    	// 维护一个Map key为session的Id， value为ScriptSession对象
    	public static final Map<String, ScriptSession> scriptSessionMap = new HashMap<String, ScriptSession>();
    
    	/**
    	 * ScriptSession创建事件
    	 */
    	@Override
    	public void sessionCreated(ScriptSessionEvent event) {
    		WebContext webContext = WebContextFactory.get();
    		HttpSession session = webContext.getSession();
    		ScriptSession scriptSession = event.getSession();
    		scriptSessionMap.put(session.getId(), scriptSession); // 添加scriptSession
    		System.out.println("session: " + session.getId() + " scriptSession: " + scriptSession.getId() + "is created!");
    	}
    
    	/**
    	 * ScriptSession销毁事件
    	 */
    	@Override
    	public void sessionDestroyed(ScriptSessionEvent event) {
    		WebContext webContext = WebContextFactory.get();
    		HttpSession session = webContext.getSession();
    		ScriptSession scriptSession = scriptSessionMap.remove(session.getId()); // 移除scriptSession
    		System.out.println("session: " + session.getId() + " scriptSession: " + scriptSession.getId() + "is destroyed!");
    	}
    
    	/**
    	 * 获取所有ScriptSession
    	 */
    	public static Collection<ScriptSession> getScriptSessions() {
    		return scriptSessionMap.values();
    	}
    
    }

新建DWRScriptSessionManager

package com.dwr.test;
    
    import org.directwebremoting.impl.DefaultScriptSessionManager;
    
    public class DWRScriptSessionManager extends DefaultScriptSessionManager {
    	public DWRScriptSessionManager() {
    		// 绑定一个ScriptSession增加销毁事件的监听器
    		this.addScriptSessionListener(new DWRScriptSessionListener());
    		System.out.println("bind DWRScriptSessionListener");
    	}
    }

新建主类MessagePush

package com.dwr.test;
    
    import java.util.Collection;
    
    import org.directwebremoting.Browser;
    import org.directwebremoting.ScriptBuffer;
    import org.directwebremoting.ScriptSession;
    import org.directwebremoting.ScriptSessionFilter;
    import org.directwebremoting.WebContextFactory;
    
    public class MessagePush {
    	public void onPageLoad(final String tag) {
    		// 获取当前的ScriptSession
    		ScriptSession scriptSession = WebContextFactory.get().getScriptSession();
    		scriptSession.setAttribute("tag", tag);
    		System.out.println("setAttribute");
    	}
    
    	public void send(String msg) {
    		if(null==msg){
    			msg="this is a message!";
    		}
    		final String content=msg;
    		// 过滤器
    		ScriptSessionFilter filter = new ScriptSessionFilter() {
    			public boolean match(ScriptSession scriptSession) {
    				String tag = (String) scriptSession.getAttribute("tag");
    				System.out.println("tag="+tag);
    				return "receiverTag".equals(tag);
    			}
    		};
    
    		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 = DWRScriptSessionListener.getScriptSessions();
    				// 遍历每一个ScriptSession
    				for (ScriptSession scriptSession : sessions) {
    					scriptSession.addScript(script);
    				}
    			}
    		};
    		// 执行推送
    		Browser.withAllSessionsFiltered(filter, run); // 注意这里调用了有filter功能的方法
    	}
    }

在web.xml同目录新建dwr.xml文件

<?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/dwr30.dtd">
    <dwr>
    	<allow>
    		<create creator="new" javascript="MessagePush">
    			<param name="class" value="com.dwr.test.MessagePush" />
    		</create>
    	</allow>
    </dwr>

在web.xml文件中添加一下配置

<servlet>
    		<servlet-name>dwr-invoker</servlet-name>
    		<servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class>
    		<init-param>
    			<param-name>org.directwebremoting.extend.ScriptSessionManager</param-name>
    			<param-value>com.dwr.test.DWRScriptSessionManager </param-value>
    		</init-param>
    		<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>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>
    			
    			<param-name>config</param-name>
    			<param-value>/WEB-INF/dwr.xml</param-value>
    		</init-param>
    		<load-on-startup>1</load-on-startup>
    	</servlet>
    
    	<servlet-mapping>
    		<servlet-name>dwr-invoker</servlet-name>
    		<url-pattern>/dwr/*</url-pattern>
    	</servlet-mapping>

jsp页面

<%@ 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 'index.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">    
    	
    	<script type="text/javascript" src="js/jquery-1.8.3.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>  
    	
    	<script>
            dwr.engine.setActiveReverseAjax(true);
    		dwr.engine.setNotifyServerOnPageUnload(true,true);
    		var tag = "receiverTag";    //自定义一个标签
            MessagePush.onPageLoad(tag);
    		dwr.engine.setErrorHandler(function(){});
    		
    		function show(content){ 
                alert(content);
            }
            
            function sendMessage(){
            	var message = dwr.util.getValue("msg");
            	MessagePush.send(message);
            }
    	</script>
      </head>
      
      <body>
        <div align="center">
           <p>
               Your Message:
               <input id="msg"  />
               <input type="button" value="Send" οnclick="sendMessage()" />
           </p>
        </div>
      </body>
    </html>

注意需要引用一下几个js

jquery-1.8.3.min.js--页面上使用到了jquery

dwr/util.js-----与下面的js都是dwr内置的，固定写法

dwr/engine.js

dwr/interface/MessagePush.js---这个是我们在dwr.xml中配置的 javascript="MessagePush"，名字对应

效果

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在文本框中输入一句话，然后点击send按钮，后台接收到消息后推送到前台页面

[Center]: https://img-blog.csdn.net/20151229171540533?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[Center 1]: https://img-blog.csdn.net/20151229172007574?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center