一、实体类中使用@NotBlank

public class User {

    @NotBlank(message="用户名为空")
    private String username;
    @NotBlank(message="用户ID为空")
    private int userid;

    public String getUsername() {
        return username;
    }

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

    public int getUserid() {
        return userid;
    }

    public void setUserid(int userid) {
        this.userid = userid;
    }

    @Override
    public String toString() {
        return ToStringBuilder.reflectionToString(this);
    }
}

二、修改controller接口

    @PostMapping(path = "/add", produces = MediaType.APPLICATION_JSON_VALUE)
    public int addUserInfo(@Valid @RequestBody User user) {
        logger.info("添加用户信息：", user.toString());
        long startTime = System.currentTimeMillis();
        int result = userService.addUser(user);
        long endTime = System.currentTimeMillis();
        logger.info("接口返回：{},调用耗时：{}", result, (endTime - startTime));
        return result;
    }

参数添加@Valid注解

三、统一异常处理类

@RestControllerAdvice(basePackageClasses={UserController.class})
public class ExceptionControllerAdvicer {
    @ExceptionHandler(Exception.class)
    public RetResult<Null> handlerArgumentException(MethodArgumentNotValidException exception){
        RetResult<Null> retResult=new RetResult<>();
        retResult.setRetCode(400);
        List<ObjectError> allErrors = exception.getBindingResult().getAllErrors();
        StringBuilder stringBuilder=new StringBuilder();
        Iterator<ObjectError> iterator = allErrors.iterator();
        while (iterator.hasNext()){
            stringBuilder.append(iterator.next().getDefaultMessage());
        }
        retResult.setRetMessage(stringBuilder.substring(0,stringBuilder.lastIndexOf(",")));
        return retResult;
    }
}

@RestControllerAdvice：指定要扫描的包或者具体类名
@ExceptionHandler(Exception.class):参数是某个异常类的class，代表这个方法专门处理该类异常