校验参数为空

1，'org.hibernate.validator:hibernate-validator:6.0.17.Final'导入检验包
2，
  @NotBlank(message = "图片url不能为空")
    private String picUrl;
3，public Result saveObject(@RequestBody @Valid DemoDto dto) {

4，建立全局捕获异常类
package com.exception;


import com.ka.common.api.ResultJson;
import com.ka.common.error.ErrorCode;
import lombok.extern.slf4j.Slf4j;
import org.springframework.dao.DuplicateKeyException;
import org.springframework.validation.BindException;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.RestControllerAdvice;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.validation.ConstraintViolation;
import javax.validation.ConstraintViolationException;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

/**
* @description 全局异常
* @author zys
* @date 2022-10-27
*/
@RestControllerAdvice(annotations = RestController.class)
@Slf4j
public class GlobalExceptionHandler {

@ExceptionHandler(value = Exception.class)
public ResultJson errorHandler(HttpServletRequest request, HttpServletResponse response, Exception e)throws Exception{
if (e instanceof BusinessException) {
log.error("BusinessException业务处理异常:\t",e);
return ResultJson.badRequest(ErrorCode.GENERIC_ERROR.getCode(),e.getMessage());
}
if (e instanceof DuplicateKeyException) {
log.error("SQLIntegrityConstraintViolationException业务处理异常:\t",e);
return ResultJson.badRequest(ErrorCode.GENERIC_ERROR.getCode(),"数据重复");
}
if (e instanceof ParamException) {
log.error("ParameterException参数异常:\t",e);
return ResultJson.badRequest(ErrorCode.BIZ_ERROR_PARAMETER.getCode(),e.getMessage());
}
log.error("GlobalExceptionHandler处理异常:\t",e);
return ResultJson.badRequest("系统异常，请稍后再试");
}

/**
* 处理 form data方式调用接口校验失败抛出的异常
* @param e
* @return
*/
@ExceptionHandler(BindException.class)
public ResultJson<?> handleBindException(BindException e) {
List<FieldError> fieldErrors = e.getBindingResult().getFieldErrors();
/*List<String> collect = fieldErrors.stream()
.map(o -> o.getDefaultMessage())
.collect(Collectors.toList());*/
String collect = fieldErrors.stream()
.map(o -> o.getDefaultMessage())
.collect(Collectors.joining());
return ResultJson.badRequest(ErrorCode.BIZ_ERROR_PARAMETER.getCode(),"参数校验失败,"+ collect);
}


/**
* 处理 json 请求体调用接口校验失败抛出的异常
* @param e
* @return
*/
@ExceptionHandler(MethodArgumentNotValidException.class)
public ResultJson<?> handleMethodArgumentNotValidException(MethodArgumentNotValidException e) {
List<FieldError> fieldErrors = e.getBindingResult().getFieldErrors();
/*List<String> collect = fieldErrors.stream()
.map(o -> o.getDefaultMessage())
.collect(Collectors.toList());*/
String collect = fieldErrors.stream()
.map(o -> o.getDefaultMessage())
.collect(Collectors.joining());
return ResultJson.badRequest(ErrorCode.BIZ_ERROR_PARAMETER.getCode(),"参数校验失败,"+ collect);
}

/**
* 处理单个参数校验失败抛出的异常
* @param e
* @return
*/
@ExceptionHandler(ConstraintViolationException.class)
public ResultJson<?> handleConstraintViolationException(ConstraintViolationException e) {
Set<ConstraintViolation<?>> constraintViolations = e.getConstraintViolations();
/*List<String> collect = constraintViolations.stream()
.map(o -> o.getMessage())
.collect(Collectors.toList());*/
String collect = constraintViolations.stream()
.map(o -> o.getMessage())
.collect(Collectors.joining());
return ResultJson.badRequest(ErrorCode.BIZ_ERROR_PARAMETER.getCode(),"参数校验失败,"+ collect);
}


}