使用Blobstore API将文件上传到Google云端存储

Question

I am trying to upload files from the browser to GCS. I am using blobstore API to upload files.

I went through the documentation and I could not find how to upload blob to GCS.

How do I get the file from blobkey so that I could upload it to GCS.

JSP side

 <form action="<%= blobstoreService.createUploadUrl("/upload") %>"
       method="post" enctype="multipart/form-data">
   <input type="file" name="myFile">
   <input type="submit" value="Submit">
 </form>

servletSide

 Map<String, BlobKey> blobs = blobstoreService.getUploadedBlobs(req);
 BlobKey blobKey = blobs.get("myFile");
 GcsService gcsService = GcsServiceFactory.createGcsService();
 GcsFilename filename = new GcsFilename(BUCKETNAME, "exampleFile");
 GcsFileOptions options = new GcsFileOptions.Builder().mimeType("text/plain")
                          .acl("authenticated-read")
                          .addUserMetadata("myfield1", "my field value")
                          .build();
 gcsService.createOrReplace(filename, options, /*File from the blob key */);

Can any one help me how to save the files into GCS?

Answer 1

after going through the java docs i was able to figure out how to upload blob and multiple blob file to gcs.

<form action="<%= blobstoreService.createUploadUrl("/upload") %>"
   method="post" enctype="multipart/form-data">
 <input type="file" name="myFile">
 <input type="file" name="myFile2">
 <input type="file" name="myFile3">
 <input type="submit" value="Submit">
</form>

servlet side

instead of getting upload blobkey info

Map<String, List<BlobKey>> blobkeylist = blobstoreService.getUploads(request);

i got blobInfos

Map<String, List<BlobInfo>> blobsData = blobstoreService.getBlobInfos(request);
for (String key : blobsData.keySet())
    {
        for(BlobInfo blob:blobsData.get(key))
        {
            byte[] b = new byte[(int)blob.getSize()];
            BlobstoreInputStream in = new BlobstoreInputStream(blob.getBlobKey());
            in.read(b);

            GcsService gcsService = GcsServiceFactory.createGcsService();
            GcsFilename filename = new GcsFilename(BUCKETNAME, "/testFolder3/"+blob.getFilename());
            GcsFileOptions options = new GcsFileOptions.Builder()
            .mimeType(blob.getContentType())
            .acl("authenticated-read")
            .addUserMetadata("myfield1", "my field value")
            .build();

            gcsService.createOrReplace(filename, options,ByteBuffer.wrap(b));
            in.close();
        }
    }

this one worked. im not sure if it is the best solution, but its working.

Answer 2

When you see a blobkey, the file is already uploaded to GCS. You can resave it with different options, if you want, but you don't have to upload it again - it's already in your bucket.

Answer 3

请参阅https://developers.google.com/appengine/docs/java/blobstore/#Java_Using_the_Blobstore_API_with_Google_Cloud_Storage （您需要提供createUploadUrl以及将googleStorageBucketName设置为目标存储区的UploadOptions）。