CODEWITHSUNDEEP
javagoogle-app-engineblobstore
Moshe Shaham
Moshe Shaham

Reputation: 15974

How to read the contents of an uploaded blob?

I'm using Blobstore to upload a simple text file using this doc: https://cloud.google.com/appengine/docs/java/blobstore/#Java_Uploading_a_blob . I understand from the docs how to save and serve the blob to users, but I don't understand how can my servlet that handle the file upload actually read the contents of the text file?

Upvotes: 0

Views: 456

Answers (2)

Moshe Shaham
Moshe Shaham

Reputation: 15974

I found the answers. This is the code:

Map<String, List<FileInfo>> infos = blobstoreService.getFileInfos(request);
Long fileSize = infos.get("myFile").get(0).getSize();
Map<String, List<BlobKey>> blobKeys = blobstoreService.getUploads(request);
byte[] fileBytes = 
        blobstoreService.fetchData(blobKeys.get("myFile").get(0), 0, fileSize);
String input = new String(fileBytes);

Upvotes: 1

user2771609
user2771609

Reputation: 1903

In python there is the BlobReader class to help you do this. (https://cloud.google.com/appengine/docs/python/blobstore/blobreaderclass)

It seems like you are using Java though. There does not seem to be an equivalent class in Java. What I would do is to use GCS as the backing for you blobstore (https://cloud.google.com/appengine/docs/java/blobstore/#Java_Using_the_Blobstore_API_with_Google_Cloud_Storage). This way the files uploaded to the blobstore will be accessibly in GCS.

You can then read the file using the GCS client library for Java.

Upvotes: 0

Related Questions