How to download the files from AWS S3 into local system using java

       HOW TO DOWNLOAD THE FILES FROM AWS S3 INTO LOCAL SYSTEM USING JAVA

• First, create the object of AWSCredentials and pass the aws_access_key_id and aws_secret_access_key as parameters.
• Next, create the s3client object for connecting to the aws s3 bucket.
• For creating a connection we can pass the AWSCredentials object as a parameter.
• Next, create the TransferManager object using s3client, TransferManager provides asynchronous management for uploads and downloads between your application.
• Using the s3client.listObjects get all list of object in aws s3 bucket.
• Using Iteratoriterate the al objects. using the S3ObjectSummary object to get all information of the object(file name.lastmodified date).
• Finally, close the connection of TransferManager object otherwise it's running continuously.
• Using the shutdownNow(); the method to close the connection.

import com.amazonaws.AmazonClientException; import com.amazonaws.AmazonServiceException; import com.amazonaws.auth.AWSCredentials; import com.amazonaws.auth.BasicAWSCredentials; import com.amazonaws.services.s3.AmazonS3; import com.amazonaws.services.s3.AmazonS3Client; import com.amazonaws.services.s3.model.GetObjectRequest; import com.amazonaws.services.s3.model.ListObjectsRequest; import com.amazonaws.services.s3.model.ObjectListing; import com.amazonaws.services.s3.model.S3Object; import com.amazonaws.services.s3.model.S3ObjectSummary; import com.amazonaws.services.s3.transfer.TransferManager; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.PrintStream; import java.util.Iterator; import java.util.List; /** * * @author Janardhan Randhi * Date : Feb 4 2019 * Description : This class Downlaod the files from AWS S3 bucket into local system. * */ public class AWSFiledownload { public AWSFiledownload() {} public static void main(String[] args) throws AmazonClientException, InterruptedException, FileNotFoundException, IOException { //create a client connection based on credentials AWSCredentials credentials = new BasicAWSCredentials("***************key", "*****************pwd"); AmazonS3 s3client = new AmazonS3Client(credentials); // create bucket - name must be unique for all S3 users also small letter required String bucketName = "BucketName"; String key = "test_folder/"; //folder name long startTime = System.currentTimeMillis(); TransferManager xfer_mgr = new TransferManager(s3client); try { ObjectListing objectListing = s3client.listObjects(new ListObjectsRequest() .withBucketName(bucketName) .withPrefix(key)); Iterator localIterator = objectListing.getObjectSummaries().iterator(); if (localIterator.hasNext()) { S3ObjectSummary objectSummary = (S3ObjectSummary)localIterator.next(); System.out.println(objectSummary.getKey()); S3Object object = s3client.getObject(new GetObjectRequest(bucketName, objectSummary.getKey())); InputStream reader = new BufferedInputStream(object.getObjectContent()); File file = new File("C:\\Users\\Administrator\\Desktop\\AWS_Download\\" + objectSummary.getKey()); OutputStream writer = new BufferedOutputStream(new FileOutputStream(file)); int read = -1; while ((read = reader.read()) != -1) { writer.write(read); } writer.flush(); writer.close(); reader.close(); s3client.deleteObject(bucketName, objectSummary.getKey()); } } catch (AmazonServiceException e) { System.err.println(e.getMessage()); } finally { xfer_mgr.shutdownNow(); } System.out.println("All File are downloaded successfully from " + key + " Directory and Deleted in " + key + "Directory"); long endTime = System.currentTimeMillis(); System.out.println("Time taken to download a multiple files : " + (endTime - startTime) + " milliseconds"); } }

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