How to use 'compose' on GCS using the Java client

Question

I want to combine multiple GCS files into one big file. According to the docs there is a compose function, which looks like it does exactly what I need: https://developers.google.com/storage/docs/json_api/v1/objects/compose

However, I can't find how to call that function from GAE using the Java client: https://developers.google.com/appengine/docs/java/googlecloudstorageclient/

Is there a way to do this with that library?

Or should I mess around with reading the files one by one using channels?

Or should I call the low level JSON methods?

What's the best way?

SANN3 SANN3 · Accepted Answer · 2019-07-31T11:05:48

Compose option available in the new Java client, I have tried using google-cloud-storage:1.63.0.

  /** Example of composing two blobs. */
  // [TARGET compose(ComposeRequest)]
  // [VARIABLE "my_unique_bucket"]
  // [VARIABLE "my_blob_name"]
  // [VARIABLE "source_blob_1"]
  // [VARIABLE "source_blob_2"]
  public Blob composeBlobs(
      String bucketName, String blobName, String sourceBlob1, String sourceBlob2) {
    // [START composeBlobs]
    BlobId blobId = BlobId.of(bucketName, blobName);
    BlobInfo blobInfo = BlobInfo.newBuilder(blobId).setContentType("text/plain").build();
    ComposeRequest request =
        ComposeRequest.newBuilder()
            .setTarget(blobInfo)
            .addSource(sourceBlob1)
            .addSource(sourceBlob2)
            .build();
    Blob blob = storage.compose(request);
    // [END composeBlobs]
    return blob;
  }

How to use 'compose' on GCS using the Java client

2 Answers