SpringBoot 上传文件判空以及格式检验流程

基于jsr303 通过自定义注解实现，实现思路：

存在一些瑕疵，后续补充完善。

加入依赖

部分版本已不默认自动引入该依赖，选择手动引入

<dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-validation</artifactId>
       </dependency>

创建自定义注解以及实现类

目录结构：

• FileNotEmpty 自定义注解

• FileNotEmptyValidator 单文件校验

• FilesNotEmptyValidator 多文件校验

/**
* jsr303 文件格式校验注解
*
* @author maofs
* @version 1.0
* @date 2021 -11-29 10:16:03
*/
@Documented
@Constraint(
       validatedBy = {FileNotEmptyValidator.class, FilesNotEmptyValidator.class}
)
@Target({ElementType.METHOD, ElementType.FIELD, ElementType.ANNOTATION_TYPE, ElementType.CONSTRUCTOR, ElementType.PARAMETER, ElementType.TYPE_USE})
@Retention(RetentionPolicy.RUNTIME)
public @interface FileNotEmpty {
   /**
    * Message string.
    *
    * @return the string
    */
   String message() default "文件格式不正确";
   /**
    * 校验组
    *
    * @return the class [ ]
    */
   Class<?>[] groups() default {};
   /**
    * Payload class [ ].
    *
    * @return the class [ ]
    */
   Class<? extends Payload>[] payload() default {};
   /**
    * 需要校验的格式数组
    *
    * @return the string [ ]
    */
   String[] format() default {};
   /**
    * 是否必填 为false时文件为空则不校验格式，不为空则校验格式
    * 为true时文件不能为空且需要验证格式
    *
    * @return the boolean
    */
   boolean required() default true;

/**
* 单文件校验
*
* @author maofs
* @version 1.0
* @date 2021 -11-29 10:16:03
*/
public class FileNotEmptyValidator implements ConstraintValidator<FileNotEmpty, MultipartFile> {
   private Set<String> formatSet = new HashSet<>();
   private boolean required;
   @Override
   public void initialize(FileNotEmpty constraintAnnotation) {
       String[] format = constraintAnnotation.format();
       this.formatSet = new HashSet<>(Arrays.asList(format));
       this.required = constraintAnnotation.required();
   }
   @Override
   public boolean isValid(MultipartFile multipartFile, ConstraintValidatorContext constraintValidatorContext) {
       if (multipartFile == null || multipartFile.isEmpty()) {
           return !required;
       }
       String originalFilename = multipartFile.getOriginalFilename();
       assert originalFilename != null;
       String type = originalFilename.substring(originalFilename.lastIndexOf('.') + 1).toLowerCase();
       if (!formatSet.isEmpty()) {
           return formatSet.contains(type);
       }
       return true;
   }
}

/**
*  多文件校验
*
* @author maofs
* @version 1.0
* @date 2021 -11-29 10:16:03
*/
public class FilesNotEmptyValidator implements ConstraintValidator<FileNotEmpty, MultipartFile[]> {
   private Set<String> formatSet = new HashSet<>();
   private boolean required;
   @Override
   public void initialize(FileNotEmpty constraintAnnotation) {
       String[] format = constraintAnnotation.format();
       this.formatSet = new HashSet<>(Arrays.asList(format));
       this.required = constraintAnnotation.required();
   }
   @Override
   public boolean isValid(MultipartFile[] multipartFiles, ConstraintValidatorContext constraintValidatorContext) {
       if (multipartFiles == null || multipartFiles.length == 0) {
           return !required;
       }
       for (MultipartFile file : multipartFiles) {
           String originalFilename = file.getOriginalFilename();
           assert originalFilename != null;
           String type = originalFilename.substring(originalFilename.lastIndexOf('.') + 1).toLowerCase();
           if (formatSet.isEmpty() || !formatSet.contains(type)) {
               return false;
           }
       }
       return true;
   }
}

全局异常处理

/**
* 统一异常处理
*
* @author maofs
* @version 1.0
* @date 2021 -11-29 10:16:03
*/
@ControllerAdvice
public class ExceptionHandle {
   private final static Logger logger = LoggerFactory.getLogger(ExceptionHandle.class);

@ExceptionHandler(value = Exception.class)
   @ResponseBody
   public Result<String> handle(Exception e) {
       logger.error(e.getMessage());
       StringBuilder stringBuilder = new StringBuilder();            
           //jsr303异常
         if (e instanceof ConstraintViolationException) {
           ConstraintViolationException ex = (ConstraintViolationException)e;
           Set<ConstraintViolation<?>> constraintViolations = ex.getConstraintViolations();
           for (ConstraintViolation<?> constraintViolation : constraintViolations) {
               stringBuilder.append(constraintViolation.getMessageTemplate());
           }
       } else if (e instanceof BindException) {
           BindException bindException = (BindException)e;
           stringBuilder.append(bindException.getFieldErrors()
               .stream()
               .map(FieldError::getDefaultMessage)
               .collect(Collectors.joining(",")));
       } else {
           stringBuilder.append("未知错误:").append("请联系后台运维人员检查处理！");          
       }
       return  ResultUtil.fail(stringBuilder.toString());
   }    
}

使用示例

/**
* 文件上传示例接口
*
* @author maofs
* @version 1.0
* @date 2021 -11-19 16:08:26
*/
@RestController
@Validated
@RequestMapping("/annex")
public class AnnexController {
@Resource
private IAnnexService annexService;
  /**
    * 文件上传示例1
    *
    * @param uploadDTO the upload dto
    * @return the result
    */
   @PostMapping(value = "/upload1")
   public Result<String> upload(@Valid AnnexUploadDTO uploadDTO) {
       return Boolean.TRUE.equals(annexService.upload(uploadDTO)) ? ResultUtil.success() : ResultUtil.fail();        
   }

/**
    * 文件上传示例2
    *
    * @param number      项目编号
    * @param pictureFile 图片文件
    * @param annexFile   附件文件
    * @return result result
    */
   @PostMapping(value = "/upload2")
   public Result<String> upload(@NotBlank(@FileNotEmpty(format = {"png", "jpg"}, message = "图片为png/jpg格式", required = false)
                                        MultipartFile pictureFile, @FileNotEmpty(format = {"doc", "docx", "xls", "xlsx"}, message = "附件为doc/docx/xls/xlsx格式", required = false)
                                        MultipartFile annexFile) {      
       return Boolean.TRUE.equals(annexService.upload( pictureFile, annexFile)) ? ResultUtil.success() : ResultUtil.fail();
   }

@Data
static class AnnexUploadDTO{
   @FileNotEmpty(format = {"pdf","doc","zip"}, message = "文件为pdf/doc/zip格式")
   private MultipartFile[] file;
   }
}

结果展示

来源：https://blog.csdn.net/weixin_43931248/article/details/122000087