最简单的DWR例子

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最简单的DWR例子
什么是DWR？

DWR是一个Open Source的 java项目。DWR可以让JavaScript调用运行在Web服务器里面的JAVA程序。简单一点或者专业一点就是Easy AJAX for JAVA. 官方网站：http://getahead.org/dwr ，下面将一步一步的介绍怎么完成一个简单DEMO :TestDwr。

一、从官方网站下载DWR.jar包

把他直接放到apache-tomcat-7.0.27lib目录下面

二、新建Web Project工程

编写一个TestDwr.Java类如下:

// TestDwr.java
[java] view plain copy print ?

package com.test.ajax;

publicclass TestDwr

{

    public String getMyName()

    {

        return"Hello Casco!";

    }

}
```
package com.test.ajax;

publicclass TestDwr

{   

    public String getMyName()

    {      

        return"Hello Casco!"; 

    }      

}  
```
三、修改web.xml

// web.xml
[html] view plain copy print ?

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

<web-app version="3.0"

    xmlns="http://java.sun.com/xml/ns/javaee"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee

    http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

<display-name></display-name>

<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>

<welcome-file-list>

    <welcome-file>index.jsp</welcome-file>

</welcome-file-list>

</web-app>
```
<?xml version="1.0" encoding="UTF-8"?>  

<web-app version="3.0"   

    xmlns="http://java.sun.com/xml/ns/javaee"   

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   

    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee   

    http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">  

  <display-name></display-name>   

  <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>  

  <welcome-file-list>  

    <welcome-file>index.jsp</welcome-file>  

  </welcome-file-list>  

</web-app>  
```
四、新建dwr.xml文件

把TestDwr类配置在dwr.xml中，dwr.xml是DWR的配置文件，所有需要在JavaScript中调用的java的类都必须在这个文件中描述 (必须与web.xml同级)

// dwr.xml
[html] view plain copy print ?

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

<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN" "http://getahead.org/dwr/dwr30.dtd">

<dwr>

<allow>

<create creator="new" javascript="CASCO" scope="application">

<param name="class" value="com.test.ajax.TestDwr"/>

</create>

</allow>

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

<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN" "http://getahead.org/dwr/dwr30.dtd">  

<dwr>

<allow>

<create creator="new" javascript="CASCO" scope="application">

<param name="class" value="com.test.ajax.TestDwr"/>

</create>

</allow>

</dwr>
```
五、配置DWR包中的引用

把dwrWEB-INFlib复制到testDwrWebRootWEB-INFlib。

六、编写jsp文件

编写调用TestDwr类中的getMyName方法的index.jsp文件：
[javascript] view plain copy print ?

<%@ page language="java" contentType="text/html; charset=GB18030"

pageEncoding="GB18030"%>

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

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=GB18030">

<title>DWR - Test Home</title>

<script type='text/javascript' src='dwr/engine.js'></script>

<script type='text/javascript' src='dwr/util.js'></script>

<script type='text/javascript' src='dwr/interface/CASCO.js'></script>

<script language="javascript">

    var mycall=function callBack(data){

        dwr.util.setValue("demo1",data);

    }

    function showMyName(){

        CASCO.getMyName(mycall);

    }

    function clearName(){

        demo1.value="";

    }

</script>

</head>

<body>

    <h1>Ajax Test Page</h1>

    <input type="button" value="显示姓名" onclick="javascript:showMyName()">

    <input type="button" value="清空" onclick="javascript:clearName()"><br>

    <input type="text" id="demo1"><br>



</body>

</html>
```
<%@ page language="java" contentType="text/html; charset=GB18030"

  pageEncoding="GB18030"%>

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

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=GB18030">

<title>DWR - Test Home</title>

<script type='text/javascript' src='dwr/engine.js'></script>

<script type='text/javascript' src='dwr/util.js'></script>

<script type='text/javascript' src='dwr/interface/CASCO.js'></script>

<script language="javascript"> 

    var mycall=function callBack(data){

        dwr.util.setValue("demo1",data);

    }

    function showMyName(){

        CASCO.getMyName(mycall);

    }

    function clearName(){

        demo1.value="";

    }

</script>

</head>

<body>

    <h1>Ajax Test Page</h1>    

    <input type="button" value="显示姓名" onclick="javascript:showMyName()">   

    <input type="button" value="清空" onclick="javascript:clearName()"><br>    

    <input type="text" id="demo1"><br>    

 

</body>

</html>
```
七、编译运行

在浏览器中输入 http://localhost:8080/TestDwr/，按“显示姓名”按钮，即可显示我们的函数getMyName内容。
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原文地址：https://www.cnblogs.com/tbyang/p/3380469.html