DWR2中调用Servlet相关类（简单例子）

DWR2一大特性就是在DWR中可以访问WEB上下文的SERVLET，REQUEST等，主要用到的类是WebContext,WebContextFactory，使用WebContextFacotry.get()方法得到当前的WebContext，原理是将WebContext与当前thread绑定，内部使用ThreadLocal来维护。

use case：
在IE中使用JAVASCRIPT来判断制定用户名经是否已经登陆。

client(index.jsp)

<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%>

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

//为演示:假设已经登录成功

request.getSession(true).setAttribute("cur_user","jack");

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

function checkUserIsLogin(name) {

UserCheck.checkUserIsLogin(name,function(res) {

var retMsg = ( true == res ) ? "已经登录" : "未登录";

DWRUtil.setValue("msg",retMsg);

}

);

}

</script>

</head>

<body>

<input type="text" name="username" /><input type="button" value="check" onclick="checkUserIsLogin(document.all.username.value)" />当前session中保存为jack

<br/>

</body>

</html>

服务端：UserCheckUtil.java

package com.dwr;

import javax.servlet.http.HttpSession;

import org.directwebremoting.WebContext;

import org.directwebremoting.WebContextFactory;

public class UserCheckUtil {

/**

* @param username

* @return

public boolean checkUserIsLogin(String username) {

WebContext ctx = WebContextFactory.get();

HttpSession session = ctx.getSession(false);

if (null != session && username.equals(String.valueOf(session.getAttribute("cur_user"))))

return true;

else

return false;

}

配置文件：dwr.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN" "http://getahead.org/dwr/dwr20.dtd">

<dwr>

<allow>

</create>

</allow>

</dwr>

posted on 2008-01-15 11:43 rickyxing 阅读(160) 评论(0) 编辑收藏举报