研究了一天半,终于模拟出了这个功能,网上DWR的资料不少,但是真正实现客户端向服务器端精确推送消息的只有两篇文章。但是代码都只有一部分,向我这种刚开始学习DWR的人来说要看懂真的蛮难。不过即便如此,http://www.blogjava.net/stevenjohn/archive/2012/07/07/382447.html这片文章还是给了我很大帮助,再次表示感谢,下面我将这两天的研究详细记录下来备忘,也希望能帮助到像我一样的人。只写过程,不写原理(不是不写,而是有些地方我也不太懂),下面开始:
第一、在项目中引入dwr.jar,然后在web.xml中进行配置,配置如下:
- <servlet>
-
- <servlet-name>dwr-invoker</servlet-name>
- <servlet-class>
- org.directwebremoting.servlet.DwrServlet
- </servlet- <init-param>
- <param-name>crossDomainSessionSecurity</param-name>
- <param-value>false</param-value>
- </init-param>
- <param-name>allowScriptTagRemoting</param-name>
- true</param-value>
- <param-name>classes</param-name>
- <param-value>java.lang.Object</param-value>
- <param-name>activeReverseAjaxEnabled</param-name>
- <param-name>initApplicationScopeCreatorsAtStartup</param-name>
- <param-name>maxWaitAfterWrite</param-name>
- <param-value>3000</param-value>
- <param-name>debug</param-name>
- <param-name>logLevel</param-name>
- <param-value>WARN</param-value>
- </servlet>
第二:在web.xml的同级目录下新建dwr.xml文件,内容如下
<!DOCTYPEdwrPUBLIC
"-//GetAheadLimited//DTDDirectWebRemoting3.0//EN"
"http://getahead.org/dwr/dwr30.dtd">
<dwr>
<alow>
<createcreator="new"javascript="MessagePush">
<paramname="class"value="com.huatech.messageremind.service.MessagePush"/>
</create>
<createcreator="new"javascript="TestPush">
<paramname="class"value="com.huatech.messageremind.service.Test"/>
</alow>
</dwr>
这个是dwr的基本配置,MessagePush在页面的javascript中使用,这个是对被推送页面开放的java类,Test是对推送页面开放的java类。场景:管理员后台登陆,发布一条消息,通过Test推送到后台,后台通过MessagePush推送给指定的用户,当然,至于怎么找到指定的用户,下面会说。
第三,被推送的页面代码
<%@pagelanguage="java"import="java.util.*"pageEncoding="utf-8"%>
<%
Stringpath=request.getContextPath();
StringbasePath=request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPEHTMLPUBLIC"-//W3C//DTDHTML4.01Transitional//EN">
<html>
<head>
<basehref="<%=basePath%>">
<title>DWRDEMO</title>
<metahttp-equiv="pragma"content="no-cache">
<metahttp-equiv="cache-control"content="no-cache">
<metahttp-equiv="expires"content="0">
<metahttp-equiv="keywords"content="keyword1,keyword2,keyword3">
<metahttp-equiv="description"content="Thisismypage">
</head>
<scripttype='text/javascript'src='dwr/engine.js'></script>
<scripttype='text/javascript'src='dwr/util.js'></script>
<scripttype="text/javascript"src="dwr/interface/MessagePush.js"></script>
<scripttype="text/javascript">
functiononPageLoad(){
varuserId='${userinfo.humanid}';
MessagePush.onPageLoad(userId);
}
//推送信息
functionshowMessage(autoMessage){
alert(autoMessage);
</script>
<bodyonload="onPageLoad();dwr.engine.setActiveReverseAjax(true);dwr.engine.setNotifyServerOnPageUnload(true);;">
ThisismyDWRDEOMpage.<hr>
<br>
<divid="DemoDiv">demo</div>
</body>
</html>
以上代码的简单解释:
页面页面onload的3个函数都是必须的,后两个是dwr的,第一个是将登录用户的userid与对应 的scriptSession进行处理,以便精确推送的时候能找到推送对象
第四 MessagePush类中实现的方法如下:
publicvoidonPageLoad(StringuserId){
ScriptSessionscriptSession=WebContextFactory.get().getScriptSession();
scriptSession.setAttribute(userId,userId);
DwrScriptSessionManagerUtildwrScriptSessionManagerUtil=newDwrScriptSessionManagerUtil();
try{
dwrScriptSessionManagerUtil.init();
System.out.println("cacaca");
}catch(ServletExceptione){
e.printStackTrace();
}
里面对应的DwrScriptSessionManagerUtil 对应如下:
importjavax.servlet.ServletException;
importjavax.servlet.http.HttpSession;
importorg.directwebremoting.Container;
importorg.directwebremoting.ServerContextFactory;
importorg.directwebremoting.WebContextFactory;
importorg.directwebremoting.event.ScriptSessionEvent;
importorg.directwebremoting.event.ScriptSessionListener;
importorg.directwebremoting.extend.ScriptSessionManager;
importorg.directwebremoting.servlet.DwrServlet;
classDwrScriptSessionManagerUtilextendsDwrServlet{
privatestaticfinallongserialVersionUID=-7504612622407420071L;
voidinit()throwsServletException{
Containercontainer=ServerContextFactory.get().getContainer();
ScriptSessionManagermanager=container.getBean(ScriptSessionManager.class);
ScriptSessionListenerlistener=newScriptSessionListener(){
voidsessionCreated(ScriptSessionEventev){
HttpSessionsession=WebContextFactory.get().getSession();
StringuserId=((User)session.getAttribute("userinfo")).getHumanid()+"";
System.out.println("aScriptSessioniscreated!");
ev.getSession().setAttribute("userId",85); font-weight:bold">voidsessionDestroyed(ScriptSessionEventev){
System.out.println("aScriptSessionisdistroyed");
};
manager.addScriptSessionListener(listener);
第五 推送页面代码:
import="java.util.*"pageEncoding="UTF-8"%>
<title>MyJSP'MyJsp.jsp'startingpage</title>
<scripttype="text/javascript"src="<%=request.getContextPath()%>/js/jquery-1.5.1.js"></script>
<scripttype='text/javascript'src='dwr/interface/TestPush.js'></script>
functiontest(){
varmsg=document.getElementById("msgId").value;
//msg={msgId:'1',context:$("#msgContext").val()};
TestPush.sendMessageAuto(msg,"哈哈哈");
<body>
id :<inputtype="text"name="msgId"id="msgId"/><br/>
<inputtype="button"value="Send"onclick="test()"/>
第六:精确推送要实现的代码:
classTest{
voidsendMessageAuto(Stringuserid,Stringmessage){
finalStringuserId=userid;
finalStringautoMessage=message;
Browser.withAllSessionsFiltered(newScriptSessionFilter(){
booleanmatch(ScriptSessionsession){
if(session.getAttribute("userId")==null)
returnfalse;
else
return(session.getAttribute("userId")).equals(userId);
},newRunnable(){
privateScriptBufferscript=newScriptBuffer();
voidrun(){
script.appendCall("showMessage",autoMessage);
Collection<ScriptSession>sessions=Browser
.getTargetSessions();
for(ScriptSessionscriptSession:sessions){
scriptSession.addScript(script);
});
至此 这个例子的代码都已经贴出来了,应该是可以跑通的,有问题的话可以给我留言。当然,要自己写个登录,然后把userId放到session里面,这个比较简单,就不贴代码了,有问题可以在http://download.csdn.net/detail/luojia_wang/5275588上下载原项目。我只是简单的做了一个能实现功能的例子,还有很多地方要研究,比如跟spring整合,还可能有很多优化,等我继续学习一下再说. (编辑:李大同)
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