实现步骤：
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-class> <init-param> <param-name>debug</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>
<!DOCTYPEdwrPUBLIC "-//GetAheadLimited//DTDDirectWebRemoting3.0//EN" "http://getahead.org/dwr/dwr30.dtd"> <dwr> <alow> <createcreator="new"javascript="MessagePush"> <paramname="class"value="com.pcitc.lw.service.MessagePush"/> </create> <createcreator="new"javascript="TestPush"> <paramname="class"value="com.pcitc.lw.service.Test"/> </create> </alow> </dwr>
dwr的基本配置指向具体实现类，MessagePush在页面的javascript中使用（被推送者），Test推送者
第三，被推送的页面
<%@pagelanguage="java"import="java.util.*"pageEncoding="utf-8"%> <!DOCTYPEHTMLPUBLIC"-//W3C//DTDHTML4.01Transitional//EN"> <html> <head> <Metahttp-equiv="cache-control"content="no-cache"> </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.id}'; MessagePush.onPageLoad(userId); } //推送信息 functionshowMessage(mgs){ alert(mgs); } </script> <bodyonload="onPageLoad();dwr.engine.setActiveReverseAjax(true);dwr.engine.setNotifyServerOnPageUnload(true);"> <divid="DemoDiv">helloworld</div> </body> </html>
注意：页面加载时加载的函数setActiveReverseAjax和setNotifyServerOnPageUnload是dwr的，onPageLoad是将登陆的用户和scriptSession进行绑定，为以后的推送做准备。
第四 MessagePush类：
publicvoidonPageLoad(StringuserId){
ScriptSessionscriptSession=WebContextFactory.get().getScriptSession();
scriptSession.setAttribute(userId,userId);
DwRSSessionUtilss=newDwRSSessionUtil();
try{
ss.init();
}catch(ServletExceptione){
e.printStackTrace();
}
}
第五：DwRSSessionUtil ：
publicclassDwRSSessionUtilextendsDwrServlet{ publicvoidinit()throwsServletException{ Containercontainer=ServerContextFactory.get().getContainer(); ScriptSessionManagermanager=container.getBean(ScriptSessionManager.class); ScriptSessionListenerlistener=newScriptSessionListener(){ publicvoidsessionCreated(ScriptSessionEventev){ HttpSessionsession=WebContextFactory.get().getSession(); StringuserId=((User)session.getAttribute("userinfo")).getId()+""; System.out.println("aScriptSessioniscreated!"); ev.getSession().setAttribute("userId",userId); } publicvoidsessionDestroyed(ScriptSessionEventev){ System.out.println("aScriptSessionisdistroyed"); } }; manager.addScriptSessionListener(listener); } }
第五 JSP页面：
<%@pagelanguage="java"import="java.util.*"pageEncoding="UTF-8"%> <!DOCTYPEHTMLPUBLIC"-//W3C//DTDHTML4.01Transitional//EN"> <html> <head> <Metahttp-equiv="cache-control"content="no-cache"> <Metahttp-equiv="expires"content="0" <scripttype="text/javascript"src="js/jquery-2.1.js"></script> <scripttype='text/javascript'src='dwr/engine.js'></script> <scripttype='text/javascript'src='dwr/util.js'></script> <scripttype='text/javascript'src='dwr/interface/TestPush.js'></script> <scripttype="text/javascript"> functiontest(){ varmsg=document.getElementById("msgId").value; TestPush.sendMessageAuto(msg,"收到没"); } </script> </head> <body> id：<inputtype="text"name="msgId"id="msgId"/><br/> <inputtype="button"value="你好"onclick="test()"/> </body> </html>
第六：推送代码：
publicclassTest{
publicvoidsendMessageAuto(Stringuserid,Stringmessage){
finalStringuserId=userid;
finalStringautoMessage=message;
Browser.withAllSessionsFiltered(newScriptSessionFilter(){
publicbooleanmatch(ScriptSessionsession){
if(session.getAttribute("userId")==null){
returnfalse;
}else{
return(session.getAttribute("userId")).equals(userId);
}
}
},newRunnable(){
privateScriptBuffers=newScriptBuffer();
publicvoidrun(){
s.appendCall("showMessage",autoMessage);
Collection<ScriptSession>sessions=Browser.getTargetSessions();
for(ScriptSessionscriptSession:sessions){
scriptSession.addScript(s);
}
}
});
}
} 原文链接：https://www.f2er.com/ajax/162485.html