dwr与spring相结合实例

转载于：http://www.itnose.net/detail/519386.html

    AJAX，或者说是异步JavaScript和XML，描述了一种使用混合了HTML(或XHTML)和层叠样式表作为表达信息,来创建交互式的Web应用的开发技术;文档对象模型（DOM），JavaScript,动态地显示和与表达信息进行交互;并且XMLHttpRequest对象与Web服务器异步地交换和处理数据。
    DWR(直接Web远程控制)项目是在Apache许可下的一个开源的解决方案，它供给那些想要以一种简单的方式使用AJAX和 XMLHttpRequest的开发者。它具有一套Javascript功能集，它们把从HTML页面调用应用服务器上的Java对象的方法简化了。它操控不同类型的参数，并同时保持了HTML代码的可读性，它可以与spring结合在一起。

举个非常实用的小例子，检测是否有重复的用户名
1。web。xml的配置（包括spring和dwr）

<?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/j2ee/dtds/web-app_2_3.dtd">
<web-app>
    <context-param>
        <param-name>log4jConfigLocation</param-name>
        <param-value>/WEB-INF/log4j.properties</param-value>
    </context-param>
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/applicationContext.xml,/WEB-INF/main-servlet.xml</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>
    </listener>
    <servlet>
        <servlet-name>context</servlet-name>
        <servlet-class>org.springframework.web.context.ContextLoaderServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet>
        　　
        <servlet-name>dwr</servlet-name>
        　　
        <display-name>DWR Servlet</display-name>
        　　
        <description>Direct Web Remoter Servlet</description>
        　　
        <servlet-class>uk.ltd.getahead.dwr.DWRServlet</servlet-class>
        　　
        <init-param>
            　　
            <param-name>debug</param-name>
            　　
            <param-value>true</param-value>
            　　
        </init-param>
        　　
    </servlet>

    <servlet-mapping>
        <servlet-name>dwr</servlet-name>
        <url-pattern>/dwr/*</url-pattern>
    </servlet-mapping>
</web-app>

2。dwr。xml的配置
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 1.0//EN" "http://www.getahead.ltd.uk/dwr/dwr10.dtd">
<dwr>
    <allow>
      
         <create
          creator="spring"
          javascript="UserManager">
          <param name="beanName" value="UserManager"/>
        </create>
      </allow>
</dwr>
3。applicationContext.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location">
            <value>/WEB-INF/jdbc.properties</value>
        </property>
    </bean>
    <!-- Local DataSource that works in any environment -->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName">
            <value>${jdbc.driverClassName}</value>
        </property>
        <property name="url">
            <value>${jdbc.url}</value>
        </property>
        <property name="username">
            <value>${jdbc.username}</value>
        </property>
        <property name="password">
            <value>${jdbc.password}</value>
        </property>
    </bean>
     <!--OrderManager-->
    <bean id="UserManager" class="dwr.manager.UserManager">
        <property name="dataSource">
            <ref local="dataSource"/>
        </property>
    </bean>
   
    </beans>
4。。spring的bean
package dwr.manager;
import org.springframework.jdbc.core.support.JdbcDaoSupport;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;


public class UserManager extends JdbcDaoSupport {
          private final Log log = LogFactory.getLog(getClass().getName());
public boolean getUser(String username)
{
    String sql="select count(*) from user where userName=? ";
   int i=getJdbcTemplate().queryForInt(sql,new Object[]{username});
    if(i>0)
    return true;
        else
     return false;
}
}
5。jsp的代码
<%@ page contentType="text/html;charset=GBK" language="java" %>
<html>
<head><title>Simple jsp page</title></head>

<script type='text/javascript' src='<%=request.getContextPath()%>/dwr/interface/UserManager.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">
    function showResult(b) {
        if (b) {
            alert("已经有重复的登录名了！");
        } else {
            alert("登录名尚未注册过！");
        }
    }function checkRepeat(s) {
        var o = getElement(s);
        if (o) {
            UserManager.getUser(o.value, showResult);
        }
    }
    function getElement(name) {
        var result = null;
        var objs = document.getElementsByName(name);
        if (objs) {
            var o = objs[0];
            result = o;
        }
        return result;
    }
 
</script>
<body>
<input type="text" name="user" >
<input type="button" onclick="checkRepeat('user')" value="检查是否重复">

</body>
</html>
6 classpath加入dwr和spring的jar文件，注意必须有hibernate3.jar和bsf.jar，在IE和FireFox下，就可以用了。