我的理解：DWR框架是javaWeb中前后端直接交互的解决方案，用DWR框架，前端js能够直接调用后端服务，后端服务也可以直接调用前端js函数。
配置：
（1）需要Dwr.jar 包，pom配置如下：
<dependency>
<groupId>org.directwebremoting</groupId>
<artifactId>dwr</artifactId>
<version>3.0.M1</version>
</dependency>
（2）在Web.xml中配置servelet,如下：
<!-- DWR配置 -->
<servlet>
<servlet-name>dwr-invoker</servlet-name>
<servlet-class>
org.directwebremoting.servlet.DwrServlet
</servlet-class>
<init-param>
<param-name>
org.directwebremoting.extend.ServerLoadMonitor
</param-name>
<param-value>
org.directwebremoting.impl.PollingServerLoadMonitor
</param-value>
</init-param>
<!-- 默认轮询的周期是5秒中,也就是5000毫秒.如果想改变这个默认值需要下面的配置改为6秒 -->
<init-param>
<param-name>disconnectedTime</param-name>
<param-value>5000</param-value>
</init-param>
<init-param>
<description>使用服务器推技术(反转AJAX)</description>
<param-name>activeReverseAjaxEnabled</param-name>
<param-value>true</param-value>
</init-param>
<init-param>
<param-name>crossDomainSessionSecurity</param-name>
<param-value>false</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>dwr-invoker</servlet-name>
<url-pattern>/dwr/*</url-pattern>
</servlet-mapping>
（3）实现一个后端服务，就是一个普通的类
public class MessageServiceImpl {
public void sendMassage() {
ScriptBuffer sb = new ScriptBuffer();
sb.appendScript("alert(12345)");
scriptSession.addScript(sb); }
}
scriptSession对应每个链接的会话，通过写入script脚本去前端执行。scriptSession可以通过如下方式获取：
WebContext context = WebContextFactory.get(); ScriptSession session = context.getScriptSession();
（4）在WEB-INF目录下创建dwr.xml文件
<dwr> <allow><create creator="new" javascript="MessageServiceImpl" scope = "session"> <param name="class" value=".....MessageServiceImpl"></param> </create></allow></dwr>
(5)jsp中调用后端服务
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
<script src="<%=request.getContextPath()%>/dwr/engine.js"></script>
<script src="<%=request.getContextPath()%>/dwr/interface/MessageServiceImpl.js"></script>
<script>
MessageServiceImpl.sendMessage();
</script>
</head>
<body>
<h1>Hello World!</h1>
</body>
</html>
（6）接收后端推送
dwr.engine.setActiveReverseAjax(true);
时间： 2024-10-06 01:46:22