1. 基于 JSR-303(一个数据验证的规范):

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;  
}

}

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/>  

import javax.validation.Valid;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class UserController {

@RequestMapping("login")  
public String login(@Valid User user, BindingResult result) {  
   if (result.hasErrors())  
       return "user/login";  
   return "redirect:/";  
}

}

使用@NotBlank等注解，然后在要验证的地方使用@Valid 标签。最后验证的结果是在BindingResult 获取，注意据说result 要紧挨着前面的@Valid，而且是一个验证一个BindingResult参数。

2. 还有就是继承Validator 接口。