Use AJAX to asynchronously verify whether the username exists-JS Tutorial-php.cn

This time I will bring you the use of AJAX to asynchronously verify whether the user name exists, and what are the precautions for using AJAX to asynchronously verify whether the user name exists. The following is a practical case, let's take a look. Use AJAX to complete asynchronous verification of whether the user name exists:

1. Event triggering:

* onblur

2. Write AJAX code:

* Submit in item Action: pass username parameter

3. Write Action

* to receive username :Model driven reception.

4.* Write entity class

* User

* User.hbm.xml

* Configure into spring.

5. Write DAO

* Inherit HibernateDaoSupport

* Inject sessionFactory

## in the configuration #6. Write Service:

* Inject UserDao

* Transaction management:

Core code implementation:

function checkUsername(){ 
    // 获得文件框值: 
    var username = document.getElementById("username").value; 
    // 1.创建异步交互对象 
    var xhr = createXmlHttp(); 
    // 2.设置监听 
    xhr.onreadystatechange = function(){ 
      if(xhr.readyState == 4){ 
        if(xhr.status == 200){ 
          document.getElementById("span1").innerHTML = xhr.responseText; 
        } 
      } 
    } 
    // 3.打开连接 
    xhr.open("GET","${pageContext.request.contextPath}/user_findByName.action?time="+new Date().getTime()+"&username="+username,true); 
    // 4.发送 
    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; 
     }

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public String findByName() throws IOException { 
    // 调用Service进行查询: 
    User existUser = userService.findByUsername(user.getUsername()); 
    // 获得response对象,项页面输出: 
    HttpServletResponse response = ServletActionContext.getResponse(); 
    response.setContentType("text/html;charset=UTF-8"); 
    // 判断 
    if (existUser != null) { 
      // 查询到该用户:用户名已经存在 
      response.getWriter().println("<font color=&#39;red&#39;>用户名已经存在</font>"); 
    } else { 
      // 没查询到该用户:用户名可以使用 
      response.getWriter().println("<font color=&#39;green&#39;>用户名可以使用</font>"); 
    } 
    return NONE; 
  }

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private UserDao userDao; 
  public void setUserDao(UserDao userDao) { 
    this.userDao = userDao; 
  } 
  // 按用户名查询用户的方法: 
  public User findByUsername(String username){ 
    return userDao.findByUsername(username); 
  }

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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; 
  }

Copy after login

<?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"> 
  <!-- 配置连接池: --> 
  <!-- 引入外部属性文件 --> 
  <context:property-placeholder location="classpath:jdbc.properties"/> 
  <!-- 配置C3P0连接池: --> 
  <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的相关信息 --> 
  <bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"> 
    <!-- 注入连接池 --> 
    <property name="dataSource" ref="dataSource"/> 
    <!-- 配置Hibernate的其他的属性 --> 
    <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> 
  <!-- 事务管理: --> 
  <!-- 事务管理器 --> 
  <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> 
    <property name="sessionFactory" ref="sessionFactory"/> 
  </bean> 
  <!-- 开启注解事务 --> 
  <tx:annotation-driven transaction-manager="transactionManager"/> 
  <!-- Action的配置 ===========================--> 
  <!-- 首页访问的Action --> 
  <bean id="indexAction" class="cn.itcast.shop.index.action.IndexAction" scope="prototype"> 
  </bean> 
  <!-- 配置验证码Action --> 
  <bean id="checkImgAction" class="cn.itcast.shop.user.action.CheckImgAction" scope="prototype"> 
  </bean> 
  <!-- 用户模块的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上查看代码片派生到我的代码片
<?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> 
    <!-- 配置首页访问的Action --> 
    <action name="index" class="indexAction"> 
      <result name="index">/WEB-INF/jsp/index.jsp</result> 
    </action> 
    <!-- 配置用户模块的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> 
    <!-- 验证码Action --> 
    <action name="checkImg" class="checkImgAction"></action> 
  </package> 
</struts>

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I believe you have read the case in this article You have mastered the method. For more exciting information, please pay attention to other related articles on the php Chinese website!