Springboot-服务器校验规则

在后端开发的过程中，验证前端参数的合法性是一个必不可少的步骤

一、依赖


    org.springframework.boot
    spring-boot-starter-web



    org.springframework.boot
        spring-boot-starter-thymeleaf

二 实体类

package com.example.demo.entity;

import sun.plugin2.message.Message;

import javax.validation.constraints.NotBlank;
import javax.validation.constraints.NotNull;

public class User {


    public Integer ID;

   public Integer getID() {
        return ID;
}

    public void setID(int ID) {
        this.ID = ID;
   }

   //不填写 message  就显示默认值
    @NotBlank(message ="用户不能为空")
    public String UserName;
    @NotBlank(message="用户密码不能为空") 
    public String Pwd;
    public String Age;

    public String getUserName() {
        return UserName;
    }

    public User(Integer ID, String userName, String pwd, String age) {
        this.ID = ID;
        UserName = userName;
        Pwd = pwd;
        Age = age;
    }

    public void setUserName(String userName) {
        UserName = userName;
    }

    public String getPwd() {
        return Pwd;
    }

    public void setPwd(String pwd) {
        Pwd = pwd;
    }



    public String getAge() {
        return Age;
    }

    public void setAge(String age) {
        Age = age;
    }
}

三 控制器Controller

package com.example.demo.Controller;

import com.example.demo.entity.User;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.validation.Valid;

@Controller
public class UserController {

    /*
    如果想更改对象可以用 @ModelAttribute("aa") ，这表示当前传递的对象Key也要修改 默认可以不用 @ModelAttribute("aa")
     */
    @RequestMapping("/ShowPage")
   public String ShowPage(@ModelAttribute("aa") User user)
   {
       return "AddUserInfo";

   }

   /*
   添加用户
   @Valid 开启对User对象的数据校验
   BindingResult 封装了校验的结果
    */
    @RequestMapping("/Add")
    public  String Save(@ModelAttribute("aa")  @Valid User user, BindingResult result)
    {

     if(result.hasErrors())
     {
         return "AddUserInfo";

     }
        return "OK";
    }
}
四 页面显示 @ModelAttribute("aa") 与 th:errors="${aa.UserName} 要一至

    
    




    用户名aa.UserName}"> 

    用户密码aa.Pwd}"> 

    用户性别

    

五 结果