com.amazonaws.services.s3.transfer.internal.DownloadPartCallable Maven / Gradle / Ivy

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The AWS Java SDK for Amazon S3 module holds the client classes that are used for communicating with Amazon Simple Storage Service

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/*
 * Copyright 2011-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *    http://aws.amazon.com/apache2.0
 *
 * This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
 * OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and
 * limitations under the License.
 */
package com.amazonaws.services.s3.transfer.internal;

import static com.amazonaws.services.s3.internal.Constants.MB;

import com.amazonaws.annotation.SdkInternalApi;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.model.GetObjectRequest;
import com.amazonaws.services.s3.model.S3Object;
import com.amazonaws.services.s3.model.S3ObjectInputStream;
import com.amazonaws.util.IOUtils;
import java.io.File;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.util.concurrent.Callable;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Helper class to get a part from s3, write the part data to the specified position and return the final position of the file.
 */
@SdkInternalApi
public class DownloadPartCallable implements Callable {
    private static final Log LOG = LogFactory.getLog(DownloadPartCallable.class);
    private static final int BUFFER_SIZE = 2 * MB;

    private final AmazonS3 s3;
    private final GetObjectRequest getPartRequest;
    private final File destinationFile;
    private final long position;


    public DownloadPartCallable(AmazonS3 s3,
                                GetObjectRequest getPartRequest,
                                File destinationFile,
                                long position) {
        this.s3 = s3;
        this.destinationFile = destinationFile;
        this.getPartRequest = getPartRequest;
        this.position = position;
    }

    @Override
    public Long call() throws Exception {
        RandomAccessFile randomAccessFile = new RandomAccessFile(destinationFile, "rw");
        FileChannel channel = randomAccessFile.getChannel();
        channel.position(position);
        S3ObjectInputStream objectContent = null;
        long filePosition;

        try {
            S3Object object = s3.getObject(getPartRequest);

            objectContent = object.getObjectContent();
            byte[] buffer = new byte[BUFFER_SIZE];
            int bytesRead;

            ByteBuffer byteBuffer = ByteBuffer.allocateDirect(BUFFER_SIZE);

            while ((bytesRead = objectContent.read(buffer)) > -1) {
                byteBuffer.put(buffer, 0, bytesRead);
                byteBuffer.flip();

                while (byteBuffer.hasRemaining()) {
                    channel.write(byteBuffer);
                }
                byteBuffer.clear();
            }

            filePosition = channel.position();
        } finally {
            IOUtils.closeQuietly(objectContent, LOG);
            IOUtils.closeQuietly(randomAccessFile, LOG);
            IOUtils.closeQuietly(channel, LOG);
        }
        return filePosition;
    }
}