初识dwr

DWR（Direct WebRemoting）是一个开源的类库,可以帮助开发人员开发包含AJAX技术的网站.它可以允许在浏览器里的代码使用运行在WEB服务器上的JAVA函数,就像它就在浏览器里一样.

一、dwr入门demo

开始之前请在myeclipse下建立web工程dwrWeb

下载jar包,放到你的java web应用的WEB-INF/lib 目录下.

注意:从dwr2.0开始,需要用到commons-logging包

编辑web.xml,加入servlet,让web应用支持 dwr

 <servlet>
   <display-name>DWRServlet</display-name>
 <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>

在web.xml的同级目录下建立dwr.xml文件,这个配置文件定义了dwr可以创建和调用哪些java类

<?xmlversion="1.0" encoding="UTF-8"?>
<!DOCTYPEdwr PUBLIC
   "-//GetAhead Limited//DTD Direct WebRemoting 2.0//EN"
   "http://getahead.org/dwr/dwr20.dtd">
<dwr>
  <allow>
    <create creator="new"javascript="Demo">
      <param name="class"value="com.Demo"/>
    </create>
  </allow>
</dwr>

建立java类文件

package com;
 
publicfinal class Demo
{
 public String hello(String name)
 {
  return "恭喜恭喜," + name +"你的dwr程序成功运行!Hava fun!";
 }
}

建立js文件

functionhello() {
  var name =dwr.util.getValue("name");
  Demo.hello(name,function(data) {
    dwr.util.setValue("result",data);
  });

建立index.jsp文件

<!DOCTYPEHTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
 <head>
  <meta http-equiv="Content-Type"content="text/html; charset=utf-8" />
  <script type='text/javascript'src='<%=request.getContextPath()%>/dwr/interface/Demo.js'>
        </script>
  <script type='text/javascript'src="<%=request.getContextPath()%>/dwr/engine.js">
        </script>
  <script type='text/javascript'src="<%=request.getContextPath()%>/dwr/util.js">
        </script>
  <script type='text/javascript'src='hello.js'>
        </script>
 
 </head>
 <body>
  <input type="text"name="name" value="Hello World!">
  <br>
  <input type="button"onclick="hello();" value="button">
  <br>
  <span id="result"style="background: #eeffdd; padding: 10px"></span>
 </body>
</html>

二、接下来为dwr+spring集成步骤：

新建一个web工程，导入dwr+spring所需jar，如下图

在web.xml配置文件中添加spring的配置。以及dwr的配置;

<?xmlversion="1.0" encoding="UTF-8"?>
<web-appversion="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">
    <!--Spring上下文 -->
    <context-param>
       <param-name>contextConfigLocation</param-name>
       <param-value>classpath:resource/app*.xml</param-value>
    </context-param>
    <listener>
       <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <!-- 配置DWR前端控制器 -->
    <servlet>
       <servlet-name>dwrServlet</servlet-name>
       <servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class>
       <!-- 指定配置文件 -->
        <init-param>
           <param-name>config</param-name>
           <!-- 如果有多个用","分开 -->
            <param-value>
               /WEB-INF/classes/config/dwr.xml               
            </param-value>
        </init-param>
        <init-param>
           <param-name>debug</param-name>
           <param-value>true</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
       <servlet-name>dwrServlet</servlet-name>
       <url-pattern>/dwr/*</url-pattern>
    </servlet-mapping>
</web-app>

配置applicationContext.xml

<?xmlversion="1.0" encoding="UTF-8"?>
<!--
    配置系统基础环境
 -->
<beans
   xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd"
    >           
    <bean id="demo" class="com.Demo"></bean>
</beans>

配置dwr.xml

<?xmlversion="1.0" encoding="UTF-8"?>
<!DOCTYPEdwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN""http://getahead.org/dwr/dwr20.dtd">
<!--通用dwr配置 -->
<dwr>
    <allow>
        <!-- 建立JS对象，将目标对象的方法转换成JS对象的方法-->
<createcreator="spring"javascript="Demo">
<param name="beanName" value="demo"/>
</create>
</allow>
</dwr>

dwr.xml的配置是整个与spring结合的关键。通过简单的学习，我想你也可以轻松的上手dwr了。

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