僅使用枚舉文件上傳指定的內容類型

Question

我正在使用HDImageService插件for grails來完成縮放用戶上傳的圖像的繁重工作。我創建了ImageService.groovy以保存到我的Amazon S3存儲桶。一切工作正常，用戶選擇文件，點擊發布和wahla圖像縮放，存儲和顯示。我的問題是，我不知道如何限制用戶上傳圖片以外的文件。我只想允許上傳jpeg，jpg，gif或png類型的文件。我用這些變量創建了一個ENUM類，但我不知道在哪裏或如何實現。任何人都可以點我在正確的方向

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RegistrationController.groovy：獲取文件並保存到鬥

  if (params.photo) { 
      MultipartFile file = request.getFile('photo') 
      byte[] fileBytes = file.bytes 
      ByteArrayInputStream bais = new ByteArrayInputStream(fileBytes) 
      BufferedImage image = ImageIO.read(bais) 
      def width = image.width 
      def height = image.height 
      def maxWidth = 500 

      // Calculate the ratio that we will need to resize the image 
      double ratio = 1.0f 
      if (width > maxWidth) { 
       def r = maxWidth/width 
       ratio = r < 1.0f ? r : 1.0f 
       bais.reset() 
       fileBytes = hdImageService.scale(bais, maxWidth, Math.round(height * ratio) as int) 
      } 

      geolink.custPhoto = imageService.storeS3Image(
       imageService.buildPPJPhotoPath(geolink, file.getOriginalFilename()), 
       fileBytes, 
       file.contentType 
      ) 
     } 

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ImageService.groovy：枚舉

String getFormatName(byte[] raw) { 
    try { 
     // Create an image input stream on the image 
     ImageInputStream iis = ImageIO.createImageInputStream(new ByteArrayInputStream(raw)) 

     // Find all image readers that recognize the image format 
     Iterator iter = ImageIO.getImageReaders(iis) 
     if (!iter.hasNext()) { 
      // No readers found 
      log.debug("Unable to get format") 
      return null; 
     } 

     // Use the first reader 
     ImageReader reader = (ImageReader)iter.next() 

     // Close stream 
     iis.close() 

     // Return the format name 
     log.debug("Format: ${reader.getFormatName() }") 
     return reader.getFormatName() 
    } 
    catch (IOException e) { 
     log.warn("Unable to determine image format", e) 
    } 
    // The image could not be read 
    return null; 
} 

ImageFormat getContentType(String filename) { 
    String[] parts = filename.split('\\.') 
    return ImageFormat.valueOf(parts[parts.length - 1].toUpperCase()) 
}} 

    public enum ImageFormat { 
JPEG('image/jpeg', 'jpg'), 
JPG('image/jpeg', 'jpg'), 
PNG('image/png', 'png'), 
GIF('image/gif', 'gif') 

String mimeType 
String extension 

public ImageFormat(String mime, String ext) { 
    this.mimeType = mime 
    this.extension = ext 
} 

}

Answer 1

這裏'我是如何做到的。它應該很容易修改爲一個枚舉：

def downloadedFile = request.getFile('imageFile') 
def okContentTypes = ['image/png', 'image/jpeg', 'image/jpg', 'image/gif'] 

if (!okContentTypes.contains(downloadedFile.getContentType())) { 
    myDomainInstance.errors.rejectValue("image", "Image type must be one of: ${okContentTypes}") 
}