Simple example of page push with dwr_html/css_WEB-ITnose
Implementation function: sendMsg.jsp sends a message to the background, and the background pushes the message to the showMsg.jsp page.
1. Web.xml configuration, add the following content in web.xml:
<!-- 使用DWR进行页面消息推送 --> <servlet> <display-name>DWR Servlet</display-name> <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> <!-- 使用polling和comet的方式 --> <init-param> <param-name>pollAndCometEnabled</param-name> <param-value>true</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>
2. Configure dwr.xml
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN" "http://getahead.org/dwr/dwr30.dtd"><dwr> <allow> <!-- 这里的javascript 值就是页面引用的第三个js文件的名称--> <create creator="new" javascript="SendMsg"> <param name="class">iwco.dwrs.SendMsg</param> </create> </allow></dwr>
3. java class SendMsg.java
package iwco.dwrs;import java.util.Collection;import org.directwebremoting.ScriptBuffer;import org.directwebremoting.ScriptSession;import org.directwebremoting.WebContext;import org.directwebremoting.WebContextFactory;import org.directwebremoting.proxy.dwr.Util;public class SendMsg { @SuppressWarnings("deprecation") public void sendMsg(String msg){ //得到上下文 WebContext contex = WebContextFactory.get(); //得到要推送到 的页面 dwr3为项目名称 ， 一定要加上。 Collection<ScriptSession> sessions = contex.getScriptSessionsByPage("/dwrTest/showMsg.jsp"); //不知道该怎么解释这个 ， Util util = new Util(sessions); //下面是创建一个javascript脚本 ， 相当于在页面脚本中添加了一句 show(msg); ScriptBuffer sb = new ScriptBuffer(); sb.appendScript("show("); sb.appendData(msg); sb.appendScript(")"); //推送 util.addScript(sb); } }4. Page
sendMsg.jsp
<%@ 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>sendMsg.jsp</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"> <script type="text/javascript" src="/dwrTest/dwr/util.js"></script> <script type="text/javascript" src="/dwrTest/dwr/engine.js"></script> <script type="text/javascript" src="/dwrTest/dwr/interface/SendMsg.js"></script> <script type="text/javascript" src="/dwrTest/js/jquery.min.js"></script> <script type="text/javascript"> $(function(){ dwr.engine.setActiveReverseAjax(true); $("#but").click(function(){ SendMsg.sendMsg($("#msg").val()); }); }); </script> </head> <body> <input type="text" id="msg" /> <input type="button" value="发送" id="but" /> </body></html>showMsg.jsp
<%@ 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>showMsg</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"> <script type="text/javascript" src="/dwrTest/dwr/util.js"></script> <script type="text/javascript" src="/dwrTest/dwr/engine.js"></script> <script type="text/javascript" src="/dwrTest/dwr/interface/SendMsg.js"></script> <script type="text/javascript" src="/dwrTest/js/jquery.min.js"></script> <script type="text/javascript"> $(function(){ //这句话千万不能少 ，表示允许使用推送技术 dwr.engine.setActiveReverseAjax(true); }); //这个函数是提供给后台推送的时候 调用的 function show(msg){ $("#message").text(msg); } </script> </head> <body> <div id="message" style="width: 200px;height: 200px;border: 1px solid red ; text-align: center; padding: 5px;"></div> </body></html>
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