java - 从 url 创建图像并保存在数据存储中

Question

我有一个保存用户个人资料图片的实体。为了简单起见，我只存储服务 URL。我允许我的用户裁剪他们的图像。为此，我从服务网址获取图像并创建一个 com.google.appengine.api.images.Image; 该图像没有 Blob 键，因为它是从字节数组创建的。将此图像存储为 blob 并获取服务 url 的最简单方法是什么？

URL url = new URL(currentProfile.getProfilePictureUrl());
InputStream input = url.openStream();
byte[] byteArray = IOUtils.toByteArray(input);
Image newImage = ImagesServiceFactory.makeImage(byteArray);

int imageWidth = newImage.getWidth();
int imageHeight = newImage.getHeight();

ImagesService imagesService = ImagesServiceFactory.getImagesService();
float lx = (float)x/(float)imageWidth;
float ty =  (float)y/(float)imageHeight;
float rx = (float)x2/(float)imageWidth;
float by = (float)y2/(float)imageHeight;
Transform resize = ImagesServiceFactory.makeCrop(lx, ty, rx, by);

Image transImage = imagesService.applyTransform(resize, newImage);

BlobstoreService blobStoreService = BlobstoreServiceFactory.getBlobstoreService();

//This doesn't work because transImage.getBlobKey() is null
ServingUrlOptions options =  ServingUrlOptions.Builder.withBlobKey(transImage.getBlobKey());

Answer 1

您可以write data to blobstore programmatically 。我使用这个小片段:

private BlobKey saveToBlobstore(String contentType, String imageName, byte[] imageData) throws IOException {
    // Get a file service
    FileService fileService = FileServiceFactory.getFileService();

    // Create a new Blob file and set the name to contain ref to UserImage
    AppEngineFile file = fileService.createNewBlobFile(contentType, imageName);

    // Open a channel to write to it
    FileWriteChannel writeChannel = fileService.openWriteChannel(file, true);

    writeChannel.write(ByteBuffer.wrap(imageData));
    writeChannel.closeFinally();

    // return the BlobKey
    return fileService.getBlobKey(file);
}