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dwr进行页面推送简单实例

2024-11-02 16:08:39   205人阅读

实现功能：sendMsg.jsp发送一个消息到后台，后台将消息推送到showMsg.jsp页面。

1、web.xml 配置，在web.xml里面添加如下内容：

<!-- 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、配置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类 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、页面

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=http://www.mamicode.com/"">>
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=http://www.mamicode.com/"">>

dwr进行页面推送简单实例


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