代碼：
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 http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>測試errors標籤</title>
</head>
<body>
<h3>註冊頁面</h3>
<form:form modelAttribute="user" method="post" action="register" >
<table>
<tr>
<td>姓名:</td>
<td><form:input path="username"/></td>
<td><font color="red"><form:errors path="username"/></font></td>
</tr>
<tr>
<td>性別:</td>
<td><form:input path="sex"/></td>
<td><font color="red"><form:errors path="sex"/></font></td>
</tr>
<tr>
<td>年齡:</td>
<td><form:input path="age"/></td>
<td><font color="red"><form:errors path="age"/></font></td>
</tr>
<tr>
<td><input type="submit" value="註冊"/></td>
</tr>
</table>
</form:form>
</body>
</html>User.java
package com.bean;
import java.io.Serializable;
public class User implements Serializable {
private String username;
private String sex;
private Integer age;
public User() {
super();
// TODO Auto-generated constructor stub
}
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 com.validator;
import org.springframework.validation.Errors;
import org.springframework.validation.ValidationUtils;
import org.springframework.validation.Validator;
import com.bean.User;
public class UserValidator implements Validator {
@Override
public boolean supports(Class<?> clazz) {
return User.class.equals(clazz);
}
@Override
public void validate(Object object, Errors errors) {
// 驗證username、sex和age是否爲null
ValidationUtils.rejectIfEmpty(errors, "username", null, "用戶名不能爲空");
ValidationUtils.rejectIfEmpty(errors, "sex", null, "性別不能爲空");
ValidationUtils.rejectIfEmpty(errors, "age", null, "年齡不能爲空");
}
}
UserController.java
package com.control;
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.annotation.InitBinder;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import com.bean.User;
import com.validator.UserValidator;
@Controller
public class UserController {
@RequestMapping(value="/registerForm",method=RequestMethod.GET)
public String registerForm(Model model){
User user=new User();
// model中添加屬性user，值是user對象
model.addAttribute("user",user);
return "registerForm";
}
@InitBinder
public void InitBinder(DataBinder binder){
// 設置驗證的類爲UserValidator
binder.setValidator(new UserValidator());
}
@RequestMapping(value="/register",method=RequestMethod.POST)
public String register(@Validated User user, Errors errors){
// 如果Errors對象有Field錯誤的時候，重新跳回註冊頁面，否則正常提交
if (errors.hasFieldErrors())
return "registerForm";
return "submit";
}
}
截圖：
