使用AJAX完成用戶名是否存在異步校驗:

1.事件觸發:

* onblur

2.編寫AJAX代碼:

* 項Action中提交:傳遞username參數

3.編寫Action

* 接收username:模型驅動接收.

4.* 編寫實體類

* User

* User.hbm.xml

* 配置到spring中.

5.編寫DAO

* 繼承HibernateDaoSupport

* 在配置中注入sessionFactory

6.編寫Service:

* 注入UserDao

* 事務管理:

核心代碼實現：

function checkUsername(){     // 獲得文件框值:     var username = document.getElementById("username").value;     // 1.創建異步交互對象     var xhr = createXmlHttp();     // 2.設置監聽     xhr.onreadystatechange = function(){       if(xhr.readyState == 4){         if(xhr.status == 200){           document.getElementById("span1").innerHTML = xhr.responseText;         }       }     }     // 3.打開連接     xhr.open("GET","${pageContext.request.contextPath}/user_findByName.action?time="+new Date().getTime()+"&username="+username,true);     // 4.發送     xhr.send(null);   }   function createXmlHttp(){       var xmlHttp;       try{ // Firefox, Opera 8.0+, Safari         xmlHttp=new XMLHttpRequest();       }       catch (e){         try{// Internet Explorer            xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");          }         catch (e){          try{            xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");          }          catch (e){}          }       }       return xmlHttp;      } 

public String findByName() throws IOException {     // 調用Service進行查詢:     User existUser = userService.findByUsername(user.getUsername());     // 獲得response對象,項頁面輸出:     HttpServletResponse response = ServletActionContext.getResponse();     response.setContentType("text/html;charset=UTF-8");     // 判斷     if (existUser != null) {       // 查詢到該用戶:用戶名已經存在       response.getWriter().println("<font color='red'>用戶名已經存在</font>");     } else {       // 沒查詢到該用戶:用戶名可以使用       response.getWriter().println("<font color='green'>用戶名可以使用</font>");     }     return NONE;   } 

private UserDao userDao;   public void setUserDao(UserDao userDao) {     this.userDao = userDao;   }   // 按用戶名查詢用戶的方法:   public User findByUsername(String username){     return userDao.findByUsername(username);   } 

public User findByUsername(String username){     String hql = "from User where username = ?";     List<User> list = this.getHibernateTemplate().find(hql, username);     if(list != null && list.size() > 0){       return list.get(0);     }     return null;   } 

<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans"   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   xmlns:context="http://www.springframework.org/schema/context"   xmlns:aop="http://www.springframework.org/schema/aop"   xmlns:tx="http://www.springframework.org/schema/tx"   xsi:schemaLocation="http://www.springframework.org/schema/beans    http://www.springframework.org/schema/beans/spring-beans.xsd   http://www.springframework.org/schema/context   http://www.springframework.org/schema/context/spring-context.xsd   http://www.springframework.org/schema/aop   http://www.springframework.org/schema/aop/spring-aop.xsd   http://www.springframework.org/schema/tx    http://www.springframework.org/schema/tx/spring-tx.xsd">   <!-- 配置連接池: -->   <!-- 引入外部屬性文件 -->   <context:property-placeholder location="classpath:jdbc.properties"/>   <!-- 配置C3P0連接池: -->   <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">     <property name="driverClass" value="${jdbc.driver}"/>     <property name="jdbcUrl" value="${jdbc.url}"/>     <property name="user" value="${jdbc.user}"/>     <property name="password" value="${jdbc.password}"/>   </bean>   <!-- Hibernate的相關信息 -->   <bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">     <!-- 注入連接池 -->     <property name="dataSource" ref="dataSource"/>     <!-- 配置Hibernate的其他的屬性 -->     <property name="hibernateProperties">       <props>         <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>         <prop key="hibernate.show_sql">true</prop>         <prop key="hibernate.format_sql">true</prop>         <prop key="hibernate.connection.autocommit">false</prop>         <prop key="hibernate.hbm2ddl.auto">update</prop>       </props>     </property>     <!-- 配置Hibernate的映射文件 -->     <property name="mappingResources">       <list>         <value>cn/itcast/shop/user/vo/User.hbm.xml</value>       </list>     </property>   </bean>   <!-- 事務管理: -->   <!-- 事務管理器 -->   <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">     <property name="sessionFactory" ref="sessionFactory"/>   </bean>   <!-- 開啟注解事務 -->   <tx:annotation-driven transaction-manager="transactionManager"/>   <!-- Action的配置 ===========================-->   <!-- 首頁訪問的Action -->   <bean id="indexAction" class="cn.itcast.shop.index.action.IndexAction" scope="prototype">   </bean>   <!-- 配置驗證碼Action -->   <bean id="checkImgAction" class="cn.itcast.shop.user.action.CheckImgAction" scope="prototype">   </bean>   <!-- 用戶模塊的Action -->   <bean id="userAction" class="cn.itcast.shop.user.action.UserAction" scope="prototype">     <!-- 注入Service -->     <property name="userService" ref="userService"/>   </bean>   <!-- Service的配置 ===========================-->   <bean id="userService" class="cn.itcast.shop.user.service.UserService">     <property name="userDao" ref="userDao"/>   </bean>   <!-- Dao的配置 ===========================-->   <bean id="userDao" class="cn.itcast.shop.user.dao.UserDao">     <property name="sessionFactory" ref="sessionFactory"/>   </bean> </beans> [html] view plain copy 在CODE上查看代碼片派生到我的代碼片<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE struts PUBLIC   "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"   "http://struts.apache.org/dtds/struts-2.3.dtd"> <struts>   <constant name="struts.devMode" value="false" />   <constant name="struts.enable.DynamicMethodInvocation" value="true"/>   <package name="shop" extends="struts-default" namespace="/">     <global-results>       <result name="msg">/WEB-INF/jsp/msg.jsp</result>     </global-results>     <!-- 配置首頁訪問的Action -->     <action name="index" class="indexAction">       <result name="index">/WEB-INF/jsp/index.jsp</result>     </action>     <!-- 配置用戶模塊的Action -->     <action name="user_*" class="userAction" method="{1}">       <result name="registPage">/WEB-INF/jsp/regist.jsp</result>       <result name="input">/WEB-INF/jsp/regist.jsp</result>       <result name="loginPage">/WEB-INF/jsp/login.jsp</result>       <result name="login">/WEB-INF/jsp/login.jsp</result>       <result name="loginSuccess" type="redirectAction">index</result>       <result name="quit" type="redirectAction">index</result>       <result name="checkcodeFail">/WEB-INF/jsp/regist.jsp</result>     </action>     <!-- 驗證碼Action -->     <action name="checkImg" class="checkImgAction"></action>   </package> </struts>