spring mvc的errors标签和validator用法
通过示例学习， 然后举一返三， 是最快的吸收知识的方式。 web.xml和springmvc-config.xml文件的内容同前面。 这一系列使用eclipse建立java项目时，选择动态web项目即可。 User.java package org.fkit.domain; import java.io.Serializable; public class User implements Serializable { /** * */ private static final long serialVersionUID = 1L; private String username; private String sex; private Integer age; public User() { super(); } public User(String username, String sex, Integer age) { super(); this.username = username; this.sex = sex; this.age = age; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } } UserValidator.java package org.fkit.validator; import org.fkit.domain.User; import org.springframework.validation.Errors; import org.springframework.validation.ValidationUtils; import org.springframework.validation.Validator; public class UserValidator implements Validator { @Override public boolean supports(Class<?> clazz) { return User.class.equals(clazz); } @Override public void validate(Object object, Errors errors) { ValidationUtils.rejectIfEmpty(errors, "username", null, "用户名不能为空"); ValidationUtils.rejectIfEmpty(errors, "sex", null, "性别不能为空"); ValidationUtils.rejectIfEmpty(errors, "age", null, "年龄不能为空"); } } UserController.java package org.fkit.controller; import org.fkit.domain.User; import org.fkit.validator.UserValidator; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.validation.DataBinder; import org.springframework.validation.Errors; import org.springframework.validation.annotation.Validated; import org.springframework.web.bind.WebDataBinder; import org.springframework.web.bind.annotation.InitBinder; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; @Controller public class UserController { @RequestMapping(value="/registerForm", method=RequestMethod.GET) public String registerForm(Model model) { User user = new User(); model.addAttribute("user", user); return "registerForm"; } @InitBinder public void initBinder(WebDataBinder binder) { binder.setValidator(new UserValidator()); } @RequestMapping(value="/register", method=RequestMethod.POST) public String register(@Validated User user, Errors errors) { if (errors.hasFieldErrors()) return "registerForm"; return "helloWorld"; } } registerForm.jsp <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %> <%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %> <!DOCTYPE html PUBLIC "-//W3C/DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd" > <html> <head> <meta content="text/html; charset=UTF-8" http-equiv="Content-Type"> <title>welcome</title> </head> <body> <h3>注册页面</h3> <br> <form:form modelAttribute="user" action="register" method="post"> <table> <tr> <td><label>姓名: </label></td> <td><form:input path="username"/></td> <td><font color="red"><form:errors path="username" /></font></td> </tr> <tr> <td><label>性别: </label></td> <td><form:input path="sex"/></td> <td><font color="red"><form:errors path="sex" /></font></td> </tr> <tr> <td><label>年龄: </label></td> <td><form:input path="age"/></td> <td><font color="red"><form:errors path="age" /></font></td> </tr> <tr> <td><input id="submit" type="submit" value="register"></td> </tr> </table> </form:form> </body> </html> 测试：
