dwr3的推送效能使用

dwr3的推送功能使用

1、web.xml的配置，红色部分为dwr推技术的主要配置

<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>
??<init-param>
???<param-name>logLevel</param-name>
???<param-value>ERROR</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>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>classes</param-name>
???<param-value>java.lang.Object</param-value>
??</init-param>
??<!-- 开启反转Ajax 即所谓推技术 -->
??<init-param>
???<param-name>activeReverseAjaxEnabled</param-name>
???<param-value>true</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>1000</param-value>
??</init-param>
??<!-- 对dwr scriptSession 自定义管理 -->
??<init-param>
???<param-name>org.directwebremoting.extend.ScriptSessionManager</param-name>
???<param-value>com.xx.xx.util.DwrScriptSessionManagerUtil</param-value>
??</init-param>
?</servlet>
?<servlet-mapping>
??<servlet-name>dwr-invoker</servlet-name>
??<url-pattern>/dwr/*</url-pattern>
?</servlet-mapping>

?

2、由于使用dwr推技术，在每次刷新的时候都会产生一个新的scriptsession，而dwr本身并没有对旧的scriptsession进行处理，所以需要自己对其进行处理，在初始化配置中加入自己的scriptsession管理类:DwrscriptSessionManagerUtil

public class DwrScriptSessionManagerUtil extends DefaultScriptSessionManager{
?public static final String SS_ID="DWR_ScriptSession_Id";
?public DwrScriptSessionManagerUtil(){
??try{
???addScriptSessionListener(new ScriptSessionListener() {
????
????public void sessionDestroyed(ScriptSessionEvent event) {
?????
????}
????
????public void sessionCreated(ScriptSessionEvent event) {
?????ScriptSession scriptSession = event.getSession();//得到新创建的scriptSession
?????HttpSession httpSession = WebContextFactory.get().getSession();//得到产生的httpSession
?????Users user = (Users) httpSession.getAttribute(Constant.LG_SESSION_USER);//得到当前用户

???? //如果当前用户已经退出系统，然后销毁这个scriptsession

?????if(user==null)
?????{
??????scriptSession.invalidate();??
??????httpSession.invalidate();??
??????return;
?????}
?????String ssId = (String) httpSession.getAttribute(SS_ID);//查找SS_ID
?????if(ssId!=null)
?????{
??????//说明已经存在旧的scriptSession.注销这个旧的scriptSession
??????DefaultScriptSession oldScriptSession = sessionMap.get(ssId);
??????if(oldScriptSession!=null)
??????{
???????invalidate(oldScriptSession);
??????}
?????}
?????httpSession.setAttribute(SS_ID, scriptSession.getId());
?????scriptSession.setAttribute(Constant.LG_USER_ID, user.getId());//绑定用户ID到ScriptSession上
????}
???});
??}catch (Exception e) {
???System.out.println("zhelichucuo");
???e.printStackTrace();
??}
?}
?
?public static void invalidate(String ssId)
?{
??Browser.withSession(ssId, new Runnable() {
???
???public void run() {
???? Collection<ScriptSession> sessions = Browser.getTargetSessions();
???? for(ScriptSession session : sessions)
???? {
????? session.invalidate();
???? }
???}
??});?
?}
?

}

?

3.js中开启dwr推功能

在window.onload中使用dwr.engine.setActiveReverseAjax(true);

?

4、java代码中使用dwr推功能

?

//dwr3使用新的方式进行推送，2的方法已被注明为过时，一般来说，很少是做全推送的，基本都是有针对性的半推

//送，所以我们将使用一个过滤器来过滤要推送的scriptsession,这里涉及到我的具体业务，这个过滤器的原理是会对

//所有的进行循环过滤后，将符合条件的scriptsession存放到一个集合中，才开启新线程进行处理的。

Browser.withAllSessionsFiltered(new ScriptSessionFilter() {
????
????public boolean match(ScriptSession session) {
?????Long loginUserId = (Long) session.getAttribute(Constant.LG_USER_ID);
?????if(loginUserId!=null && targetIdList.contains(loginUserId))
?????{
??????targetIdList.remove(loginUserId);//如果找到了，说明将被推送，所以不用再处理,剩下的都是要被处理的
??????return true;
?????}
?????return false;
????}
????}, new Runnable() {
????
?????private ScriptBuffer script = new ScriptBuffer();
?????public void run()
?????{
??????script.appendCall("这里写你页面的js函数", 这个参数是传给js函数的);
??????Collection<ScriptSession> sessions = Browser.getTargetSessions();
?????????????? for (ScriptSession scriptSession : sessions)
?????????????? {
?????????????????? scriptSession.addScript(script);
?????????????? }
?????//ScriptSessions.addFunctionCall("ExtTalk.updateMegGroup", data);//之所以不用这个方法，是因为这个

//方法有bug的存在，会对所有不论过不过滤的scriptsession进行推送，相当于全推送，没有起到过滤的作用
????}
???});

dwr的推功能还是很方便的，用来做消息通知还是不错的