# (二)Java Bean Validation 最佳实践

标签（空格分隔）： JSR-303

最简单的参数校验

过程步骤如下：

1. vo中添加校验注解
2. controller中使用校验

import javax.validation.constraints.Min;

public class User {

    private String username;
    @Min(value = 18,message = "不能小于18")
    private Integer age;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }



}

import javax.validation.Valid;

import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;

import com.example.demo.vo.User;

@RestController
public class HelloController {

    /**
     * 添加一个用户
     * @param user
     * @return
     */
    @PostMapping("/addUser")
    public User addUser(@Valid User user,BindingResult bindingResult) {
        if(bindingResult.hasErrors()) {
            System.out.println(bindingResult.getFieldError().getDefaultMessage());
        }
        System.out.println(user.getUsername());
        System.out.println(user.getAge());
        return user;

    }

}