]]>
]]>
]]>
]]>
]]>
]]>
]]>
]]>
]]>
]]>
]]>
它可以让你在览器中的Javascript代码调用Web服务器上的Java 代码Q就像在Java代码在览器中一栗?
DWR包含 2个主要部分：
一个运行在服务器端的Java ServletQ它处理hq且向浏览器发回响应?/span>
一个运行在览器端的JavaScriptQ它发送请求而且q能动态更新网c?
DWR工作原理是通过动态把Javacȝ成ؓJavascript。它的代码就像Ajax法一P你感觉调用就像发
生在览器端Q但是实际上代码调用发生在服务器端，DWR负责数据的传递和转换。这U从Java ?/span>
JavaScript的远E调用功能的方式使DWR用v来有U非常像RMI或者SOAP的常规RPC机制Q而且DWR
的优点在于不需要Q何的|页览器插件就能运行在|页上?
Java从根本上讲是同步机制Q然 AJAX却是异步的。所以你调用q程ҎӞ当数据已l从|络上返?/span>
的时候，你要提供有反?QcallbackQ?功能的DWR?/span>
W?1?DWR 例子QHello World
1) 从官方网站下载dwr.jar包。然后将它放在你 webapp ?WEB-INF/lib目录下?/span>
2) 修改web.xml,如下
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app id="dwr">
<display-name>DWR (Direct Web Remoting)</display-name>
<description>A Simple Demo DWR</description>
<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>
</servlet>
<servlet-mapping>
<servlet-name>dwr-invoker</servlet-name>
<url-pattern>/dwr/*</url-pattern>
</servlet-mapping>
</web-app>
3) 在WEB-INF下新建dwr.xml,内容如下
<?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 creator="new" javascript="service">
<param name="class"
value="helloworld.Service"/>
</create>
</allow>
</dwr>
4) 启动web服务器，讉Khttp://localhost/工程/dwr ,面l果昄?/span>
Classes known to DWR:
* service (helloworld.Service)
5) 点击q入 *service,看到提示....
Methods For: service (helloworld.Service)
To use this class in your javascript you will need the following script includes:
<script type='text/javascript' src='/TestDWR/dwr/interface/service.js'></script>
<script type='text/javascript' src='/TestDWR/dwr/engine.js'></script>
In addition there is an optional utility script:
<script type='text/javascript' src='/TestDWR/dwr/util.js'></script>
Replies from DWR are shown with a yellow background if they are simple or in an alert box otherwise.
The inputs are evaluated as Javascript so strings must be quoted before execution.
There are 10 declared methods:
* sayHello( );
* hashCode( );
(Warning: hashCode() is excluded: Methods defined in java.lang.Object are not accessible. See below)
* getClass( );
(Warning: No Converter for java.lang.Class. See below)
(Warning: getClass() is excluded: Methods defined in java.lang.Object are not accessible. See below)
* wait( );
(Warning: overloaded methods are not recommended. See below)
(Warning: wait() is excluded: Methods defined in java.lang.Object are not accessible. See below)
* wait( , );
(Warning: overloaded methods are not recommended. See below)
(Warning: wait() is excluded: Methods defined in java.lang.Object are not accessible. See below)
* wait( );
(Warning: overloaded methods are not recommended. See below)
(Warning: wait() is excluded: Methods defined in java.lang.Object are not accessible. See below)
* equals( );
(Warning: No Converter for java.lang.Object. See below)
(Warning: equals() is excluded: Methods defined in java.lang.Object are not accessible. See below)
* notify( );
(Warning: notify() is excluded: Methods defined in java.lang.Object are not accessible. See below)
* notifyAll( );
(Warning: notifyAll() is excluded: Methods defined in java.lang.Object are not accessible. See below)
* toString( );
(Warning: toString() is excluded: Methods defined in java.lang.Object are not accessible. See below)
6)创徏jspQ内容如?/span>
<%@ page language="java" pageEncoding="UTF-8"%>
<html>
<head>
<script type='text/javascript' src='dwr/interface/service.js'></script>
<script type='text/javascript' src='dwr/engine.js'></script>
<script type='text/javascript' src='dwr/util.js'></script>
</script>
<script type="text/javascript">
function firstDwr(){
service.sayHello(" Test ",callBackHello);
}
function callBackHello(data){
alert(data);
}
</script>
</head>
<body>
<input type="button" name="button" value="试" onclick="firstDwr()">
</body>
</html>
当点?试"Ӟ出现结果了.
ȝ:
1.在web.xml中加入dwr servlet
2.在drw.xml中指明你要调用的c?q指明生成的javascript?/span>
<create creator="new" javascript="service">
<param name="class" value="helloworld.Service"/>
</create>
3.完成对应的类
4.在html/jsp中写javascript函数Q调用java服务器端的方法，q写处理l果的回调函?/span>
]]>
其中不少都是大小写、配|文件的讄不当D , 下面ȝ一下今天遇到的问题及解军_?/span> .
一 基本步骤如下 ( 文档中已l提?/span> )
1. Ҏ Hibernate Tools 生成对应?/span> domain 对象
2. 修改 dataAccessContext-hibernate.xml, 你的新 domain 对象加入
< property name = "annotatedClasses" > ?/span>
3. 生成对象?/span> xxxManager cd , 一定要注意cM的泛?/span> , q且注意生成Ҏ的名U?/span>
4. 生成对象?/span> xxxManagerTest c?/span> ,
5. 修改 src/recources/spring / serviceContext.xml, 加入 xxxManager, ׃使用 byName q行的注入，所以配|文件比较简?/span>
6. 生成 web 上的 xxxAction, 一定要注意泛Ş , q且注意生成Ҏ的名U?/span>
7. 修改 struts-config(-module).xml, d生成?/span> xxxAction
?/span> 常见错误
1. 如果配置文g写的有问题，一般会提示 ”nested Exception” 的错?/span>
2. 配置 ServiceContext.xml Ӟ一定要注意大小写问?/span>
<
bean
id
=
"orderManager"
class
=
"org.wl.service.OrderManager"
/>
今天把
id
的值写成了cdU?/span>
OrderManager,
l果提示错误
”Error Create Bean……”
3. 我用的 mysql, 用户?/span> root, 但是?/span> Jdbc.properties 配置文g中用户名写成?/span> sa,
l果可以讉K数据库，当在 web 界面上点?/span> save Q提交后提示 “no row with the given identifier exists”
4. 如果需要?/span> extremeTable, 记得?/span> jsp 中引?/span>
<%@ taglib uri="http://www.extremecomponents.org" prefix="ec" %>
]]>