DWR的精确推送

功能需求：

有一个系统，当我们登录成功后，跳转到success.jsp页面。多人登录，每个人都会停留在这个页面。此事，我只想给一个账号叫aaa的人的success.jsp页面推送信息；其他人的success.jsp接收不到。

思路：

当一个页面调用dwr生成的js时，会产生一个scriptSession。类似与session，是一个唯一标示符。根据这个scriptSession我们可以知道到底要推给哪一个页面。鉴于此：

1.在登录的时候，我们将登录的人的信息放入到session里面(这里是session，而不是scriptSession)；这一步是在login.jsp页面提交后跳转到loginAction里面实现。

2.在登录成功后，加载success.jsp页面时，我们出发一个dwr生成的js里面的方法，此事产生一个scriptSession，我们将session中的个人信息取出来，将用户名存入scriptSession中；

3.在发送页面，push.jsp；当我们点击发送时，遍历所有的scriptSession，在scriptSession找到用户名，推送。

代码目录：

具体代码：

<span style="font-size:14px;">public class User {
	private String name;
	private String password;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
}</span>

下面定义管理器和监听器：

<span style="font-size:14px;">public class DwrScriptSessionManagerUtil extends DefaultScriptSessionManager {

	 private static final long serialVersionUID = -7504612622407420071L;
	 
	 public DwrScriptSessionManagerUtil(){
		 System.out.println("正在启动scriptSessionManager...");
		 this.addScriptSessionListener(new DwrScriptSessionListener());
	 }
		
}
</span>

<span style="font-size:14px;">public class DwrScriptSessionListener implements ScriptSessionListener{
//	public static final List list = new ArrayList<Map>();
	@Override
	public void sessionCreated(ScriptSessionEvent event) {
		// TODO Auto-generated method stub\
		System.out.println("create a new scriptSession");
		 WebContext context = WebContextFactory.get();
		 HttpSession session = context.getSession();
		 ScriptSession scriptSession = event.getSession();
		 System.out.println(scriptSession.getId());
		 //session中的username放入到scriptSession中
		 scriptSession.setAttribute("username",((User)session.getAttribute("user")).getName());
	}

	@Override
	public void sessionDestroyed(ScriptSessionEvent arg0) {
		// TODO Auto-generated method stub
		System.out.println("destroy the old scriptSession");
		 WebContext context = WebContextFactory.get();
		 HttpSession session = context.getSession();
	}

}</span>

<span style="font-size:14px;">public class Login  extends HttpServlet {

	public void doGet(HttpServletRequest request,HttpServletResponse response)
			throws ServletException,IOException {
		this.doPost(request,response);
	}

	public void doPost(HttpServletRequest request,IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");
		HttpSession session = request.getSession();
		User user = new User();
		user.setName(username);
		user.setPassword(password);
		session.setAttribute("user",user);
		response.sendRedirect("success.jsp");
	}
<span style="font-size:18px;">}</span></span>

推送：

<span style="font-size:14px;">public class PushMessage {
	
	public void pushMessage(String name,String content){
		System.out.println("准备发送消息");
		final String username = name;
		final String autoMessage  = content;
		WebContext context = WebContextFactory.get();
		Browser.withAllSessionsFiltered(new ScriptSessionFilter(){

			public boolean match(ScriptSession session) {
				//这里判断session里面保存的用户信息，获取scriptSession的情况
				if(username.equals((String)session.getAttribute("username")))
					return true;
				return false;
					
			}
		},new Runnable(){
			private ScriptBuffer script = new ScriptBuffer(); 
			@Override
			public void run() {
				// TODO Auto-generated method stub
					script.appendCall("showMessage",autoMessage);
				   Collection<ScriptSession> sessions = Browser.getTargetSessions();
				   for (ScriptSession scriptSession : sessions){  
	                    scriptSession.addScript(script);  
	                }  
			}
			
		});
	}
}</span>

<span style="font-size:14px;">public class InitRecieve {
	
	
	public void initMessage(String username){
		System.out.println("初始化将要显示推送信息的页面");
		ScriptSession scriptSession = WebContextFactory.get().getScriptSession();
		scriptSession.setAttribute("username",username);
		System.out.println(scriptSession.getId());
		HttpSession session = WebContextFactory.get().getSession();
		System.out.println(((User)session.getAttribute("user")).getName());
	}

}</span>

配置文件：

web.xml

<span style="font-size:14px;"><?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">
  
  <listener>
  	<listener-class>org.directwebremoting.servlet.DwrListener</listener-class>
  </listener>
  <servlet>
    <servlet-name>dwr</servlet-name>
    <servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class>
    <init-param>
      <param-name>debug</param-name>
      <param-value>true</param-value>
    </init-param>
    <!-- 是否可以从别的域进行请求 -->
    <init-param>
      <param-name>crossDomainSessionSecurity</param-name>
      <param-value>false</param-value>
    </init-param>
    <!-- 解决找不到注释类产生的报错 -->
       <init-param>
          <param-name>classes</param-name>
          <param-value>java.lang.Object</param-value>
        </init-param>
        <!-- 启动逆ajax，也就是推 -->
        <init-param>
            <param-name>activeReverseAjaxEnabled</param-name>
            <param-value>true</param-value>
        </init-param>
        <!-- 启动自定义管理scriptSession -->
        <init-param>
        	<param-name>org.directwebremoting.extend.ScriptSessionManager</param-name>
        	<param-value>com.mz.dwr.DwrScriptSessionManagerUtil</param-value>
        </init-param>
        <init-param>
           <param-name>initApplicationScopeCreatorsAtStartup</param-name>
           <param-value>true</param-value>
        </init-param>
        <init-param>
            <param-name>maxWaitAfterWrite</param-name>
            <param-value>3000</param-value>
        </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>dwr</servlet-name>
    <url-pattern>/dwr/*</url-pattern>
  </servlet-mapping>
  
  <servlet>
		<servlet-name>LoginAction</servlet-name>
		<servlet-class>com.mz.action.Login</servlet-class>
  </servlet>

	<servlet-mapping>
		<servlet-name>LoginAction</servlet-name>
		<url-pattern>/login.do</url-pattern>
	</servlet-mapping>
</web-app></span>

dwr.xml

<span style="font-size:14px;"><?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN" "http://getahead.org/dwr/dwr20.dtd">
<!-- 通用dwr配置 -->
<dwr>
<allow>
	<!-- 建立JS对象，将目标对象的方法转换成JS对象的方法 -->
	<create creator="new" javascript="initRecieve" >
		<param name="class" value="com.mz.action.InitRecieve"></param>
	</create>
	
	<create creator="new" javascript="pushMessage">
		<param name="class" value="com.mz.action.PushMessage"></param>
	</create>
</allow>
</dwr></span>

JSP页面：

<span style="font-size:14px;"><%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>
<%
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">    
	<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">
	-->
  </head>
  
  <body>
  <form action="login.do" method="post">
    <input type="text" id="username" name="username"><br/>
    <input type="password" id="password" name="passoword"><br/>
    <input type="submit"  value="send"/>
    </form>
  </body>
</html></span>

success.jsp

<span style="font-size:14px;"><%@ 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">    
	<Meta http-equiv="keywords" content="keyword1,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>  
  <!--在线jquery库-->      <script type='text/javascript' src='${pageContext.request.contextPath}/dwr/interface/initRecieve.js'></script>
	<script src="http://code.jquery.com/jquery-latest.js"></script>
	<script type="text/javascript">
		function init(){
			//开启推送
			dwr.engine.setActiveReverseAjax(true);
			//销毁或刷新页面时销毁当前ScriptSession
			dwr.engine.setNotifyServerOnPageUnload(true);
			//服务器关闭，取消dwr弹的错误提示框
			dwr.engine.setErrorHandler(function(){});
		}
		
		function onPageLoad(){
			initRecieve.initMessage('${user.name}');
		}
		
		 function showMessage(autoMessage){  
			alert("s");
			  $("#show").text(autoMessage);  
		 }
	</script>
  </head>
  
  <body onload="init(); onPageLoad();">
   <div id="show"></div>
  </body>
</html></span>

push.jsp

<span style="font-size:14px;"><%@ 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='${pageContext.request.contextPath}/dwr/engine.js'></script>  
    <script type='text/javascript' src='${pageContext.request.contextPath}/dwr/util.js'></script>  
    <script type='text/javascript' src='${pageContext.request.contextPath}/dwr/interface/pushMessage.js'></script>  
    <script type="text/javascript">
	function init(){
		//开启推送
		//销毁或刷新页面时销毁当前ScriptSession
		dwr.engine.setNotifyServerOnPageUnload(true);
		//服务器关闭，取消dwr弹的错误提示框
	}
    function test() {  
        var username = document.getElementById("username").value;  
        var content = document.getElementById("content").value;
        //msg = {msgId: '1',context: $("#msgContext").val()};  
        pushMessage.pushMessage(username,content);  
   //     location.reload();
          
    }  
    </script>
  </head>
  
  <body >
    username : <input type="text" name="username" id="username" /> <br />  
      <input type="text" id="content"/>
    <input type="button" value="Send" onclick="test()"  />  
   
  </body>
</html></span>

测试方法：

启动项目后，打开多个login.jsp；任意输入账号密码；

打开push.jsp; 输入刚才登录的其中一个账号；并且输出内容；查看变化。

问题：

上面说了，每当调用页面里面由dwr产生的js时都会创建一个scriptSession，所以在发送发送消息是，会发现多产了一个ScriptSession.由于我是在后台Quartz不断调度任务进行推的。所以没有用到页面推送，也就没解决这个问题。但是我觉的，在发送后立即刷新页面应该是一个解决方法。

代码打包，附上连接：

DWR的精确推送

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