Listing Keys Using the AWS SDK for Java

Example
The following example lists the object keys in a bucket. The example uses pagination to retrieve a set of object keys. If there are more keys to return after the first page, Amazon S3 includes a continuation token in the response. The example uses the continuation token in the subsequent request to fetch the next set of object keys.
For instructions on creating and testing a working sample, see Testing the Amazon S3 Java Code Examples.

import com.amazonaws.AmazonServiceException;

import com.amazonaws.SdkClientException;

import com.amazonaws.auth.profile.ProfileCredentialsProvider;

import com.amazonaws.regions.Regions;

import com.amazonaws.services.s3.AmazonS3;

import com.amazonaws.services.s3.AmazonS3ClientBuilder;

import com.amazonaws.services.s3.model.ListObjectsV2Request;

import com.amazonaws.services.s3.model.ListObjectsV2Result;

import com.amazonaws.services.s3.model.S3ObjectSummary;

import java.io.IOException;

public class ListKeys {

public static void main(String[] args) throws IOException {

Regions clientRegion = Regions.DEFAULT_REGION;

String bucketName = "*** Bucket name ***";

try {

AmazonS3 s3Client = AmazonS3ClientBuilder.standard()

.withCredentials(new ProfileCredentialsProvider())

.withRegion(clientRegion)

.build();

System.out.println("Listing objects");

// maxKeys is set to 2 to demonstrate the use of

// ListObjectsV2Result.getNextContinuationToken()

ListObjectsV2Request req = new ListObjectsV2Request().withBucketName(bucketName).withMaxKeys(2);

ListObjectsV2Result result;

do {

result = s3Client.listObjectsV2(req);

for (S3ObjectSummary objectSummary : result.getObjectSummaries()) {

System.out.printf(" - %s (size: %d)\n", objectSummary.getKey(), objectSummary.getSize());

}

// If there are more than maxKeys keys in the bucket, get a continuation token

// and list the next objects.

String token = result.getNextContinuationToken();

System.out.println("Next Continuation Token: " + token);

req.setContinuationToken(token);

} while (result.isTruncated());

} catch (AmazonServiceException e) {

// The call was transmitted successfully, but Amazon S3 couldn't process

// it, so it returned an error response.

e.printStackTrace();

} catch (SdkClientException e) {

// Amazon S3 couldn't be contacted for a response, or the client

// couldn't parse the response from Amazon S3.

e.printStackTrace();

}

}

}