为新的Blob文件创建图像服务URL [英] Create image serving URL for new Blob file
问题描述
使用ImagesService转换上传的图像后，我想将其存储回新的Blob文件，并通过 getServingUrl（）将其提供给ImagesService。
After using the ImagesService to transform an uploaded image, I would like to store it back into a new Blob file and make it available through getServingUrl() as provided by the ImagesService.
按照描述的方式将图像存储在新的AppEngineFile中这里工作正常，我可以使用开发服务器在本地打开和查看。
Storing the image in a new AppEngineFile as described here works fine and I am able to open and view it locally using the dev server.
但是当将新AppEngineFile的blobKey传递给 ImagesService.getServingUrl（） a
However when passing the blobKey for the new AppEngineFile to ImagesService.getServingUrl() a
java .lang.IllegalArgumentException：无法读取blob。
java.lang.IllegalArgumentException: Could not read blob.
抛出异常。任何想法可能是什么问题？这是我用来转换和存储上传图像的代码（blobKey和blobInfo对应于上传的文件，而不是新创建的文件）。
exception is thrown. Any ideas what the problem could be? This is the code I use to transform and store an uploaded image (blobKey and blobInfo correspond to the uploaded file, not the newly created one).
/* Transform image in existing Blob file */
Image originalImage = ImagesServiceFactory.makeImageFromBlob(blobKey);
Transform verticalFlip = ImagesServiceFactory.makeVerticalFlip();
ImagesService imagesService = ImagesServiceFactory.getImagesService();
Image newImage = imagesService.applyTransform(verticalFlip, originalImage);
/* Store newImage in an AppEngineFile */
FileService fileService = FileServiceFactory.getFileService();
AppEngineFile file = fileService.createNewBlobFile(blobInfo.getContentType());
FileWriteChannel writeChannel = fileService.openWriteChannel(file, true);
ByteBuffer buffer = ByteBuffer.wrap(newImage.getImageData());
writeChannel.write(buffer);
/* closeFinally assigns BlobKey to new file object */
writeChannel.closeFinally();
BlobKey newBlobKey = fileService.getBlobKey(file);
修改：
上面的代码是正确的，问题是使用 newBlobKey.toString（）而不是 newBlobKey存储新blob键的String表示形式。 getKeyString（）。
The above code is correct, the problem was storing a String representation of the new blob key using newBlobKey.toString() instead of newBlobKey.getKeyString().
推荐答案
以下工作正常，在发布的代码末尾执行问题：
The following works fine when executed at the end of the code posted in the question:
String url = imagesService.getServingUrl(newBlobKey)
这篇关于为新的Blob文件创建图像服务URL的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
