Springboot2.0中如何处理自定义异常并返回json

package cn.jfjb.crud.exception;

public class UserNotExistException extends RuntimeException {
  public UserNotExistException() {
    super("用户不存在");
  }
}

package cn.jfjb.crud.handler;

import cn.jfjb.crud.exception.UserNotExistException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.HashMap;
import java.util.Map;


@ControllerAdvice
public class MyExceptionHandler {

  @ResponseBody
  @ExceptionHandler(UserNotExistException.class)
  public Map<String, Object> handleException(Exception e) {
    Map<String, Object> map = new HashMap<>();
    map.put("code", "user.notexist");
    map.put("message", e.getMessage());
    return map;
  }
}

server:
 error:
  include-exception: true

package cn.jfjb.crud.controller;

import cn.jfjb.crud.exception.UserNotExistException;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;


@Controller
public class HelloController {
  
  @RequestMapping({"/testException"})
  public String testException(@RequestParam("user") String user) {
    if (user != "aaa") {
      throw new UserNotExistException();
    }
    return "index";
  }
}