DWR实例详解
1，请先参阅–DWR中文文档 v0.9 — For Dwr 2.0–这是最新版的DWR中文教程，下载DWR相关.jar包和.js文件下载地址: http://directwebremoting.org/dwr/download 找到
| Download | Version 2.0.5 | Size |
|---|---|---|
| JAR File: | dwr.jar(下载) | (490Kb) |
| WAR File: | dwr.war | (2.14Mb) |
| Sources: | dwr-2.0.5-src.zip (下载) | (20.77Mb) |
2，将dwr.jar放到: 你的工程/WEB-INF/lib/下
用解压缩软件打开-src.zip文件，进入目录:\/java\org\directwebremoting，找到engine.js和 util.js并将其解压出来，在 你的工程/WebRoot/ 下新建文件夹 dwr\interface，将engine.js和util.js放在dwr\下
以下两步为必要的准备工作，如果你要在html中测试dwr的话
3，打开WEB-INF\web.xml，修改为如下：
<?xml version=”1.0″ encoding=”UTF-8″?>
<web-app version=”2.4″
xmlns=”http://java.sun.com/xml/ns/j2ee”
xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”
xsi:schemaLocation=”http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd“>
<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>
其中黑体加粗部分为DWR2.x版的DwrServlet位置，如果用DWR1.x,应改为:
<servlet-class>uk.ltd.getahead.dwr.DWRServlet</servlet-class>
开发者应该参考dwr.jar文件中的实际位置写
4，写一个简单的类文件：
package collon;
public class Service {
public String sayHello(String yourName){
return “Welcome :” + yourName;
}
}
5，在WEB-INF\下新建dwr.xml，内容为下：
<?xml version=”1.0″ encoding=”UTF-8″?>
<!DOCTYPE dwr PUBLIC “-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN” “http://www.getahead.ltd.uk/dwr/dwr20.dtd“>
<dwr>
<allow>
<create creator=”new” javascript=”service”>
<param name=”class” value=”collon.Service”/>
<include method=”sayHello”/>
</create>
</allow>
</dwr>
注意黑体加粗字，是dwr2.0的标准DTD文档声明，其中，javascript=”service”为要生成的，可远程调用的，javascript方法名
6，启动tomcat服务器吧
7，打开网页，输入http://localhost:8080/你的工程/dwr 按回车，测试吧，会有如下输出:
Classes known to DWR:
service (collon.Service)
点service，会进入如下页面：
Methods For: service (collon.Service)
To use this class in your javascript you will need the following script includes:
<script type=\'text/javascript\' src=\'/firstDwr/dwr/interface/service.js\'></script>
<script type=\'text/javascript\' src=\'/firstDwr/dwr/engine.js\'></script>
In addition there is an optional utility script:
<script type=\'text/javascript\' src=\'/firstDwr/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( ); <script type=”text/javascript”></script> (在双引号中输入字符串，可以测试了)……………
8，点击 \’/firstDwr/dwr/interface/service.js\’ 将其保荐到 \WebRoot\dwr\interface 下
9，新建html页面，代码如下:
<%@ page language=”java” import=”java.util.*” pageEncoding=”gbk”%>
<!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Transitional//EN”>
<html>
<head>
<title>My Dwr Testing</title>
<script type=\’text/javascript\’ src=\’/你的工程/dwr/interface/service.js\’></script>
<script type=\’text/javascript\’ src=\’/你的工程/dwr/engine.js\’></script>
<script type=\’text/javascript\’ src=\’/你的工程/dwr/util.js\’></script>
<script type=\’text/javascript\’ src=\’/你的工程/js/first.js\’></script>
</head>
<body>
<input type=”text” width=”100″ id=”yourName” /><input
type=”button” value=”Click Me” onclick=”demo();” /><br />
<div id=”result”></div>
</body>
</html>
注：请注意各.js文件的位置要准确无误
10:
建立/你的工程/js/first.js 文件，内容如下:
function demo(){
service.sayHello($(\’yourName\’).value,callback);//注意，service.sayHello是js文件代码，不是Java类Service.sayHello
}
function callback(msg){
DWRUtil.setValue(“result”,msg);
}
11，输入页面测试吧
12，请我们看一看DwrServlet生成的.js代码:
// Provide a default path to dwr.engine
if (dwr == null) var dwr = {};
if (dwr.engine == null) dwr.engine = {};
if (DWREngine == null) var DWREngine = dwr.engine;
if (service == null) var service = {};
service._path = \’/firstDwr/dwr\’;
service.sayHello = function(p0, callback) {
dwr.engine._execute(service._path, \’service\’, \’sayHello\’, p0, callback);
}
不知道大家看出点什么没有
好了，就写到就里了，有时间再研究一下 DWR 的 源代码