校验器,Validator。 在处理带有表单数据的HTTP请求时,通常这样做: ~~~ if (表单数据符合要求) { 处理数据,返回结果; } else { 返回结果,提示用户重新输入数据; } ~~~ 判断表单数据是否符合要求这就是校验器该做的事情。我们可以自己编写校验类,也可以使用Spring MVC自带的相关类。 ## [](https://github.com/someus/another-tutorial-about-java-web/blob/master/01-06.md#将表单数据绑定到对象中)将表单数据绑定到对象中 项目结构如下: [![](https://box.kancloud.cn/2015-10-17_5621d5e80eb35.png)](https://github.com/someus/another-tutorial-about-java-web/blob/master/img/01-06/01.png) ### [](https://github.com/someus/another-tutorial-about-java-web/blob/master/01-06.md#源码)源码 **web.xml** ~~~ <?xml version="1.0" encoding="UTF-8"?> <web-app version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"> <context-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/applicationContext.xml</param-value> </context-param> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <servlet> <servlet-name>dispatcher</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>2</load-on-startup> </servlet> <servlet-mapping> <servlet-name>dispatcher</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> <session-config> <session-timeout> 30 </session-timeout> </session-config> <welcome-file-list> <welcome-file>redirect.jsp</welcome-file> </welcome-file-list> </web-app> ~~~ **applicationContext.xml** ~~~ <?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:p="http://www.springframework.org/schema/p" 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-4.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd"> </beans> ~~~ **dispatcher-servlet.xml** ~~~ <?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:p="http://www.springframework.org/schema/p" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd"> <context:component-scan base-package="me.letiantian.controller" /> <mvc:annotation-driven/> <bean class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping"/> <bean id="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping"> <property name="mappings"> <props> <prop key="index">indexController</prop> </props> </property> </bean> <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" /> <bean name="indexController" class="org.springframework.web.servlet.mvc.ParameterizableViewController" p:viewName="index" /> </beans> ~~~ **hello/input.jsp** ~~~ <%@page contentType="text/html" pageEncoding="UTF-8"%> <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>JSP Page</title> </head> <body> <form method="POST" action="${pageContext.request.contextPath}/hello/output"> First Name: <input type="text" name="firstName"> <br/> Second Name: <input type="text" name="secondName"> <br/> <input type="submit" /> </form> </body> </html> ~~~ **hello/output.jsp** ~~~ <%@page contentType="text/plain" pageEncoding="UTF-8"%> first name: ${person.firstName} second name: ${person.secondName} ~~~ **Person.java** ~~~ package me.letiantian.form; public class Person { private String firstName; private String secondName; public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getSecondName() { return secondName; } public void setSecondName(String secondName) { this.secondName = secondName; } } ~~~ **HelloController.java** ~~~ package me.letiantian.controller; import java.io.PrintWriter; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import me.letiantian.form.Person; import org.springframework.web.bind.annotation.ModelAttribute; @Controller @RequestMapping("/hello") public class HelloController{ @RequestMapping(value = "") public String index() { return "index"; } @RequestMapping(value = "/input") public String input() { return "hello/input"; } @RequestMapping(value = "/output") public String output(Person person, Model model) { model.addAttribute("person", person); return "hello/output"; } // @RequestMapping(value = "/output") // public String output(@ModelAttribute(value="person") Person person, Model model) { // return "hello/output"; // } } ~~~ 注意, ~~~ @RequestMapping(value = "/output") public String output(Person person, Model model) { model.addAttribute("person", person); return "hello/output"; } ~~~ 和 ~~~ @RequestMapping(value = "/output") public String output(@ModelAttribute(value="person") Person person, Model model) { return "hello/output"; } ~~~ 是一样的。 ### [](https://github.com/someus/another-tutorial-about-java-web/blob/master/01-06.md#浏览器访问)浏览器访问 表单填入信息: [![](https://box.kancloud.cn/2015-10-17_5621d5e820257.png)](https://github.com/someus/another-tutorial-about-java-web/blob/master/img/01-06/02.png) 提交表单后: [![](https://box.kancloud.cn/2015-10-17_5621d5e82ecf8.png)](https://github.com/someus/another-tutorial-about-java-web/blob/master/img/01-06/03.png) ## [](https://github.com/someus/another-tutorial-about-java-web/blob/master/01-06.md#校验数据)校验数据 ### [](https://github.com/someus/another-tutorial-about-java-web/blob/master/01-06.md#helloinputjsp修改如下)hello/input.jsp修改如下 ~~~ <%@page contentType="text/html" pageEncoding="UTF-8"%> <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <%@taglib prefix="form" uri="http://www.springframework.org/tags/form" %> <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title> JSP Page</title> <style type="text/css"> .error {color: red;} </style> </head> <body> <form:form modelAttribute="person" method="POST" action="${pageContext.request.contextPath}/hello/output"> firstName: <form:input path="firstName" /> <form:errors path="firstName" cssClass="error"/> <br/> secondName: <form:input path="secondName" /> <form:errors path="secondName" cssClass="error"/> <br/> <input type="submit" value="提交" /> </form:form> </body> </html> ~~~ 注意`<form:form modelAttribute="person"`。 ### [](https://github.com/someus/another-tutorial-about-java-web/blob/master/01-06.md#hellocontrollerjava修改如下)HelloController.java修改如下 ~~~ package me.letiantian.controller; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping; import me.letiantian.form.Person; import me.letiantian.validator.PersonValidator; import org.springframework.validation.BindingResult; @Controller @RequestMapping("/hello") public class HelloController{ @RequestMapping(value = "") public String index() { return "index"; } @RequestMapping(value = "/input") public String input(Model model) { model.addAttribute("person", new Person()); // 很重要 return "hello/input"; } @RequestMapping(value = "/output") public String output(Person person, BindingResult bindingResult, Model model) { model.addAttribute("person", person); // 很重要 PersonValidator pv = new PersonValidator(); pv.validate(person, bindingResult); if (bindingResult.hasErrors()) { // 如果有错误,BindingResult是Errors的子类 return "hello/input"; } return "hello/output"; } } ~~~ 注意每个方法中的`model.addAttribute("person")`是和`hello/input.jsp`中的`<form:form modelAttribute="person"`对应的。 ### [](https://github.com/someus/another-tutorial-about-java-web/blob/master/01-06.md#添加personvalidatorjava)添加PersonValidator.java 该文件在包`me.letiantian.validator`下,内容为: ~~~ package me.letiantian.validator; import me.letiantian.form.Person; import org.springframework.validation.Errors; import org.springframework.validation.Validator; import org.springframework.validation.ValidationUtils; public class PersonValidator implements Validator{ @Override public boolean supports(Class<?> type) { return Person.class.isAssignableFrom(type); } @Override public void validate(Object o, Errors errors) { Person person = (Person) o; ValidationUtils.rejectIfEmptyOrWhitespace(errors, "firstName", null, "firstName不能为空"); ValidationUtils.rejectIfEmptyOrWhitespace(errors, "secondName", null, "secondName不能为空"); if (person.getFirstName().length() < 2) { errors.rejectValue("firstName", null, "firstName太短"); } } } ~~~ ### [](https://github.com/someus/another-tutorial-about-java-web/blob/master/01-06.md#测试)测试 **第1组:** [![](https://box.kancloud.cn/2015-10-17_5621d5e839e4d.png)](https://github.com/someus/another-tutorial-about-java-web/blob/master/img/01-06/04.png) [![](https://box.kancloud.cn/2015-10-17_5621d5e843baa.png)](https://github.com/someus/another-tutorial-about-java-web/blob/master/img/01-06/05.png) **第2组:** [![](https://box.kancloud.cn/2015-10-17_5621d5e84ffff.png)](https://github.com/someus/another-tutorial-about-java-web/blob/master/img/01-06/06.png) [![](https://box.kancloud.cn/2015-10-17_5621d5e85b861.png)](https://github.com/someus/another-tutorial-about-java-web/blob/master/img/01-06/07.png) **第3组:** [![](https://box.kancloud.cn/2015-10-17_5621d5e86a438.png)](https://github.com/someus/another-tutorial-about-java-web/blob/master/img/01-06/08.png) [![](https://box.kancloud.cn/2015-10-17_5621d5e87794a.png)](https://github.com/someus/another-tutorial-about-java-web/blob/master/img/01-06/09.png)