import javax.validation.constraints.Min;import javax.validation.constraints.NotNull;import org.hibernate.validator.constraints.NotBlank; public class User {     private String username;       private String password;       private int age;     @NotBlank(message="用户名不能为空")    public String getUsername() {       return username;    }     public void setUsername(String username) {       this.username = username;    }     @NotNull(message="密码不能为null")    public String getPassword() {       return password;    }     public void setPassword(String password) {       this.password = password;    }     @Min(value=10, message="年龄的最小值为10")    public int getAge() {       return age;    }     public void setAge(int age) {       this.age = age;    }   }

<?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:mvc="http://www.springframework.org/schema/mvc"    xsi:schemaLocation="http://www.springframework.org/schema/beans     http://www.springframework.org/schema/beans/spring-beans-3.0.xsd     http://www.springframework.org/schema/context     http://www.springframework.org/schema/context/spring-context-3.0.xsd     http://www.springframework.org/schema/mvc     http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">        <mvc:annotation-driven/></beans>

import javax.validation.Valid;import org.springframework.stereotype.Controller;import org.springframework.validation.BindingResult;import org.springframework.web.bind.annotation.RequestMapping; @Controllerpublic class UserController {     @RequestMapping("login")    public String login(@Valid User user, BindingResult result) {       if (result.hasErrors())           return "user/login";       return "redirect:/";    }   }