DWR3使用

导入官方demo里面的jar包

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>
			<!-- dwr配置文件路径 -->
			<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">    
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
	<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" onclick="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

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

原文链接：https://www.f2er.com/ajax/162553.html

猜你在找的Ajax相关文章