CODEWITHSUNDEEP
javaamazon-web-servicesamazon-s3
Sachin RT
Sachin RT

Reputation: 77

List All the Objects in AWS S3 using Java SDK

I am using the following code snippet for listing objects in a bucket.

objectListing = client.listObjects(bucketname);
do{
   for (S3ObjectSummary objectSummary : objectListing.getObjectSummaries()) {
         System.out.printf(" - %s (size: %d)\n", objectSummary.getKey(), objectSummary.getSize());
        }
         objectListing=s3Client.listNextBatchOfObjects(objectListing);
  }while (objectListing.isTruncated());

I am not able to get the last batch of objects.I did some research regarding this and the batches are being saved in list.But I am not able to use list to save all the objects as there are million of objects and this will cause the heap memory problem sometimes.How can i get all the objects.Thanks!!!

New:

I am running this:

    BasicAWSCredentials credentials = new BasicAWSCredentials("foo", "bar");
    client = AmazonS3ClientBuilder
    .standard()
    .withCredentials(new AWSStaticCredentialsProvider(credentials))
    .withEndpointConfiguration(new AwsClientBuilder.EndpointConfiguration("http://localhost:" + port, null))
    .withPathStyleAccessEnabled(true)
    .withChunkedEncodingDisabled(true)
    .build();
    ObjectListing listing = client.listObjects( "bucketname");
    System.out.println("Listing size "+listing.getObjectSummaries().size());
    System.out.println("At 0 index "+ listing.getObjectSummaries().get(0).getKey());
    System.out.println("At 999 index "+ listing.getObjectSummaries().get(999).getKey());
    while (listing.isTruncated()) {
              System.out.println("-----------------------------------------------");
        listing = client.listNextBatchOfObjects(listing);
        System.out.println("Listing size "+listing.getObjectSummaries().size());
        System.out.println("At 0 index "+ listing.getObjectSummaries().get(0).getKey());
        System.out.println("At 999 index "+ listing.getObjectSummaries().get(1000).getKey());
}

I am getting following result:

Listing size 1000
At 0 index folder1/a.gz
At 999 index folder1/b.gz
---------------------------------------------------------------
Listing size 1001
At 0 index folder1/b.gz
At 1000 index folder1/d.gz
---------------------------------------------------------------
Listing size 1001
At 0 index folder1/d.gz
At 1000 index folder1/e.gz

Upvotes: 1

Views: 4212

Answers (1)

raevilman
raevilman

Reputation: 3259

Simple and Straightforward 

ObjectListing listing = s3.listObjects( bucketName, prefix );
List<S3ObjectSummary> summaries = listing.getObjectSummaries();

while (listing.isTruncated()) {
   listing = s3.listNextBatchOfObjects (listing);
   summaries.addAll (listing.getObjectSummaries());
}

Or 

ObjectListing listing = s3.listObjects( bucketName, prefix );
doSomeProcessing(listing);

while (listing.isTruncated()) {
   listing = s3.listNextBatchOfObjects (listing);
   doSomeProcessing(listing);
}

Update:
On the below comment of repeating elements, I ran below code

Yeah,I am getting objects but the 1000 and 1001 objects are repeating and so 2001 and 2002 objects are repeating and so on.How can i avoid this by second method @raevilman. Thank You

public static void main(String[] args) {
        int i=0;
        System.out.println("start");
        ObjectListing listing = s3Client.listObjects( "emr-logs");
        System.out.println("Listing size "+listing.getObjectSummaries().size());
        System.out.println("At 0 index "+ listing.getObjectSummaries().get(0).getKey());
        System.out.println("At 999 index "+ listing.getObjectSummaries().get(999).getKey());
        while (listing.isTruncated()) {
            if(i>3)break;
            System.out.println("========================================================================");
            listing = s3Client.listNextBatchOfObjects(listing);
            System.out.println("Listing size "+listing.getObjectSummaries().size());
            System.out.println("At 0 index "+ listing.getObjectSummaries().get(0).getKey());
            System.out.println("At 999 index "+ listing.getObjectSummaries().get(999).getKey());
            i++;
        }
        System.out.println("end");
    }

I got the below results, without repeating elements 

start
Listing size 1000
At 0 index j-10HD9DMBVVTJL/containers/application_1507189355052_0001/container_1507189355052_0001_01_000001/stderr.gz
At 999 index j-156WGS0LMKA2I/node/i-00085367e194fc02a/daemons/instance-state/instance-state.log-2017-11-16-05-15.gz
========================================================================
Listing size 1000
At 0 index j-156WGS0LMKA2I/node/i-00085367e194fc02a/daemons/instance-state/instance-state.log-2017-11-16-05-30.gz
At 999 index j-182UIXOOU8GZ6/node/i-061ffd1d1ae11da74/provision-node/0d1707a0-71dd-4dd5-a1dc-ab226ee2d150/stdout.gz
========================================================================
Listing size 1000
At 0 index j-182UIXOOU8GZ6/node/i-061ffd1d1ae11da74/provision-node/apps-phase/stderr.gz
At 999 index j-1BW9J554DDY15/containers/application_1521803257216_0002/container_1521803257216_0002_01_000002/stderr.gz
========================================================================
Listing size 1000
At 0 index j-1BW9J554DDY15/containers/application_1521803257216_0002/container_1521803257216_0002_01_000002/stdout.gz
At 999 index j-1EKRPTSEXCTB5/node/i-0576a3c452d00384b/applications/hadoop/steps/s-2B5LZ2PC741FD/controller.gz
========================================================================
Listing size 1000
At 0 index j-1EKRPTSEXCTB5/node/i-0576a3c452d00384b/applications/hadoop/steps/s-2B5LZ2PC741FD/stderr.gz
At 999 index j-1G6AYY5EMTR94/node/i-02363f6ac11c89135/daemons/instance-state/instance-state.log-2017-10-29-14-15.gz
end

Process finished with exit code 0

Upvotes: 2

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