Use AJAX to verify whether the user name exists asynchronously.

Use AJAX to verify whether the user name exists asynchronously.

Use AJAX to verify whether the user name exists asynchronously:

1. event triggering:

* Onblur

2. Compile AJAX code:

* Submit in item Action: Pass the username parameter

3. Write Action

* Receiving username: model-driven receiving.

4. * compile entity classes

* User

* User. hbm. xml

* Configure it to spring.

5. Write DAO

* Inherit from HibernateDaoSupport

* Inject sessionFactory into the configuration.

6. Compile the Service:

* Inject UserDao

* Transaction management:

Core code implementation:

Function checkUsername () {// obtain the file box value: var username = document. getElementById ("username "). value; // 1. create an Asynchronous interaction object var xhr = createXmlHttp (); // 2. set the xhr listener. onreadystatechange = function () {if (xhr. readyState = 4) {if (xhr. status = 200) {document. getElementById ("span1 "). innerHTML = xhr. responseText ;}}// 3. open the connection xhr. open ("GET", "$ {pageContext. request. contextPath}/user_findByName.action? Time = "+ new Date (). getTime () + "& username =" + username, true); // 4. send 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 {// call Service to query: User existUser = userService. findByUsername (user. getUsername (); // get the response object. The output of the item Page is HttpServletResponse response = ServletActionContext. getResponse (); response. setContentType ("text/html; charset = UTF-8"); // judge if (existUser! = Null) {// query the user: the user name already has a response. getWriter (). println ("<font color = 'red'> the user name already exists </font>");} else {// This user is not found: the user name can use response. getWriter (). println ("<font color = 'green'> User name can be used </font>");} return NONE ;}

Private UserDao userDao; public void setUserDao (UserDao userDao) {this. userDao = userDao;} // User query method by User name: 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 "> <! -- Configure the connection pool: --> <! -- Introduce the External property file --> <context: property-placeholder location = "classpath: jdbc. properties"/> <! -- Configure the C3P0 connection pool: --> <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-related information --> <bean id = "sessionFactory" class = "org. springframework. orm. hibernate3.LocalSessionFactoryBean"> <! -- Inject connection pool --> <property name = "dataSource" ref = "dataSource"/> <! -- Configure other attributes of Hibernate --> <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> <! -- Configure the Hibernate ing file --> <property name = "mappingResources"> <list> <value> cn/itcast/shop/user/vo/User. hbm. xml </value> </list> </property> </bean> <! -- Transaction Management: --> <! -- Transaction Manager --> <bean id = "transactionManager" class = "org. springframework. orm. hibernate3.HibernateTransactionManager "> <property name =" sessionFactory "ref =" sessionFactory "/> </bean> <! -- Enable annotation transaction --> <tx: annotation-driven transaction-manager = "transactionManager"/> <! -- Action configuration =================================--> <! -- Homepage access Action --> <bean id = "indexAction" class = "cn. itcast. shop. index. action. indexAction "scope =" prototype "> </bean> <! -- Configure the verification code Action --> <bean id = "checkImgAction" class = "cn. itcast. shop. user. action. CheckImgAction" scope = "prototype"> </bean> <! -- User Module Action --> <bean id = "userAction" class = "cn. itcast. shop. user. action. UserAction" scope = "prototype"> <! -- Inject Service --> <property name = "userService" ref = "userService"/> </bean> <! -- Service configuration ===========================--> <bean id = "userService" class = "cn. itcast. shop. user. service. userService "> <property name =" userDao "ref =" userDao "/> </bean> <! -- Dao configuration =============================--> <bean id = "userDao" class = "cn. itcast. shop. user. dao. userDao "> <property name =" sessionFactory "ref =" sessionFactory "/> </bean> </beans> [html] view plain copy: view the CODE piece on the CODE and derive it from me <? 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> <! -- Configure the homepage access Action --> <action name = "index" class = "indexAction"> <result name = "index">/WEB-INF/jsp/index. jsp </result> </action> <! -- Configure the user Module 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 = "redirectAct Ion "> index </result> <result name =" checkcodeFail ">/WEB-INF/jsp/regist. jsp </result> </action> <! -- Verification Code Action --> <action name = "checkImg" class = "checkImgAction"> </action> </package> </struts>

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