Springboot怎么使用校验注解把错误提示返回给前端

package cn.jiyun.controller;

import cn.jiyun.common.DataGridView;
import cn.jiyun.pojo.Emp;
import cn.jiyun.service.EmpService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.validation.FieldError;
import org.springframework.validation.ObjectError;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.validation.Valid;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.List;

@Controller
public class EmpController {

@Autowired
public EmpService empService;
/*@Autowired
public RestTemplate restTemplate;*/

/* @Autowired//选cloud包
public DiscoveryClient discoveryClient;*/

/* @RequestMapping(“list”)
@ResponseBody
public List list(Teacher teacher){

    //List list = restTemplate.getForObject("http://localhost:8090/show", List.class);

//
String json = JsonUtil.obj2String(list);
System.out.println(“json串”+json);

    System.out.println("===============================");
    List list1 = JsonUtil.string2Obj(json, List.class);
    System.out.println("反序列化+"+list1.toString());*//*
   *//* //获取服务集群
    List serviceInstanceList = discoveryClient.getInstances("shengchan");
    //获取当前服务实例
    ServiceInstance instance = serviceInstanceList.get(0);
    //请求地址动态拼接
    String url="http://"+instance.getHost()+":"+instance.getPort()+"/show";*//*
    //负载均衡
    String url="http://shengchan/show";

    List list = restTemplate.getForObject(url, List.class);
    System.out.println("================="+"消费者");
    return  list;
}*/




@RequestMapping(value = "show")
@ResponseBody
public DataGridView  show(Emp emp, Model model){

    List list=empService.show(emp);
    //model.addAttribute("list",list);


    return  new DataGridView(list);
}

//添加
@RequestMapping("toadd")
public String toadd(){




    return  "add";
}
//去页面

/* @RequestMapping("/{show}")
public String toshow(@PathVariable(“show”)String show){

    return  show;
}*/
//去页面
@RequestMapping("toshow")
public String show2(){




    return  "show";
}




@RequestMapping("add")
public String add(@Valid Emp emp, BindingResult bindingResult,Model model) throws ParseException {

    if(!bindingResult.hasErrors()){
        String date = emp.getDate();
        SimpleDateFormat format=new SimpleDateFormat("yyyy-MM-dd");
        Date birthday = format.parse(date);
        emp.setBirthday(birthday);
        empService.add(emp);
        return  "redirect:show";

    }

    else{
        List list = bindingResult.getAllErrors();

        for (int i = 0; i < list.size(); i++) {
            FieldError  error = (FieldError )list.get(i);
            String field = error.getField();
            String message = error.getDefaultMessage();
            System.out.println(field+"出错"+"错误信息:"+message);
            HashMap map = new HashMap<>();
            map.put(field,message);
            model.addAllAttributes(map);
        }


        return  "add";
    }


}
//修改
@RequestMapping("update")
public String update(Emp emp) throws ParseException {

    String date = emp.getDate();
    SimpleDateFormat format=new SimpleDateFormat("yyyy-MM-dd");
    Date birthday = format.parse(date);
    emp.setBirthday(birthday);
    empService.update(emp);
    return  "redirect:show";
}
@RequestMapping("toupdate")
public String toupdate(Emp emp, Model model) throws ParseException {


    Emp e=empService.findByid(emp.getEid());
    Date birthday = e.getBirthday();
    SimpleDateFormat format=new SimpleDateFormat("yyyy-MM-dd");
    String s = format.format(birthday);
    e.setDate(s);
    model.addAttribute("e",e);
    return  "update";
}
@RequestMapping("deletebyid")
public String deletebyid(Emp emp, Model model) throws ParseException {

    empService.deletebyid(emp.getEid());

    return  "redirect:show";
}

}
html页面

添加 姓名:
生日:
did: