DWR简单应用实例

xiaobojava · 发表于 2013-1-23 02:26:56

1。在使用DWR之前要去下载一个dwr.jar包(http://directwebremoting.org/dwr/download.html)加入到你的程序当中去。
2。在web.xml加班DWR配置如下：
<servlet><servlet-name>dwr</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</servlet-name><url-pattern>/dwr/*</url-pattern></servlet-mapping>
3。完成我们的Ajax调用的方法如：
public class UserDAO {EntityManagerFactory factory = null;EntityManager manager = null;public void persist(User user) {factory = Persistence.createEntityManagerFactory("mengya");manager = factory.createEntityManager();manager.getTransaction().begin();manager.persist(user);manager.getTransaction().commit();manager.close();factory.close();}public boolean exitUserName(String name) {boolean flag = false;factory = Persistence.createEntityManagerFactory("mengya");manager = factory.createEntityManager();Query query = manager.createQuery("select u from User u where u.username=:username");query.setParameter("username", name);List<User> userList = query.getResultList();if (userList.size() != 0) {flag = true;}manager.close();factory.close();return flag;}}
   专门写一个包里面存放我们Ajax调用的方法如下：

package com.mengya.AjaxDAO;import com.mengya.dao.UserDAO;public class UserAjaxDAO {private UserDAO userDao=new UserDAO();public boolean exitUserName(String name){return userDao.exitUserName(name);}}
4。配置我们的DWR里的dwr.xml（注意该文件要与web.xml同一个目录下面）如下：
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 1.0//EN" "http://www.getahead.ltd.uk/dwr/dwr10.dtd"><dwr><allow> <create javascript="UserAjaxDAO" creator="new"><param name="class"value="com.mengya.AjaxDAO.UserAjaxDAO"></param></create><convert match="com.mengya.bean.User" converter="bean"></convert></allow></dwr>
5。在页面上完成对Ajax的使用如下：
<html>
<head>
    
<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/UserAjaxDAO.js"></script>
    <title>用户注册</title>
    <script type="text/javascript">
    function show(boolean){
      if(boolean){
       ${"error"}.style.visibility="visible";
       form1.username.value="";
      }else{
       ${"error"}.style.visibility="hidden";
      }
    }
    function validate(){
      var name=form1.username.value;
      //show表示该Ajax回调方法
      UserAjaxDAO.exitUserName(name,show);
    }
    function init(){
      ${"error"}.style.visibility="hidden";
    }
    </script>
</head>

<body >
<form action="#" name="form1">
  <table id="table1" border="0">
   <tr>
    <td>用户名：</td>
    <td>
     <input type="text" name="username" onchange="validate()">
    </td>
    <td id="error">
     <font color="red">用户名已存在！</font>
    </td>
   </tr>
   <tr>
    <td>密码：</td>
    <td>
     <input type="password" name="password">
    </td>
   </tr>
  </table>
</form>
</body>
</html>

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