com.davidsoergel.s3napback.StreamingServiceUtils.java Source code

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Here is the source code for com.davidsoergel.s3napback.StreamingServiceUtils.java

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/*
 * Copyright (c) 2008-2013  David Soergel  <dev@davidsoergel.com>
 * Licensed under the Apache License, Version 2.0
 * http://www.apache.org/licenses/LICENSE-2.0
 */

package com.davidsoergel.s3napback;

import com.amazonaws.AmazonClientException;
import com.amazonaws.services.s3.internal.ServiceUtils;
import com.amazonaws.services.s3.model.S3Object;
import com.amazonaws.util.BinaryUtils;
import com.amazonaws.util.Md5Utils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;

/**
 * @author <a href="mailto:dev@davidsoergel.com">David Soergel</a>
 * @version $Id$
 */
public class StreamingServiceUtils {
    private static final Logger log = LoggerFactory.getLogger(StreamingServiceUtils.class);

    // copied from com.amazonaws.services.s3.internal.ServiceUtils in order to modify

    /**
     * Downloads an S3Object, as returned from {@link com.amazonaws.services.s3.AmazonS3Client#getObject(com.amazonaws.services.s3.model.GetObjectRequest)
     * }, to
     * the specified file.
     *
     * @param s3Object        The S3Object containing a reference to an InputStream containing the object's data.
     * @param destinationFile The file to store the object's data in.
     */
    public static void downloadObjectToStream(S3Object s3Object, BufferedOutputStream eventualOutputStream) {
        /*
              // attempt to create the parent if it doesn't exist
              File parentDirectory = destinationFile.getParentFile();
              if (parentDirectory != null && !parentDirectory.exists())
                 {
                 parentDirectory.mkdirs();
                 }
        */

        ByteArrayOutputStream byteOS = new ByteArrayOutputStream(
                (int) s3Object.getObjectMetadata().getContentLength());
        OutputStream outputStream = null;
        try {
            // perf extra copying, left over from file outputstream version
            outputStream = new BufferedOutputStream(byteOS);
            byte[] buffer = new byte[1024 * 10];
            int bytesRead;
            while ((bytesRead = s3Object.getObjectContent().read(buffer)) > -1) {
                outputStream.write(buffer, 0, bytesRead);
            }
        } catch (IOException e) {
            try {
                s3Object.getObjectContent().abort();
            } catch (IOException abortException) {
                log.warn("Couldn't abort stream", e);
            }
            throw new AmazonClientException("Unable to store object contents to disk: " + e.getMessage(), e);
        } finally {
            try {
                outputStream.close();
            } catch (Exception e) {
            }
            try {
                s3Object.getObjectContent().close();
            } catch (Exception e) {
            }
        }

        try {
            // Multipart Uploads don't have an MD5 calculated on the service side
            if (ServiceUtils.isMultipartUploadETag(s3Object.getObjectMetadata().getETag()) == false) {
                byte[] clientSideHash = Md5Utils.computeMD5Hash(byteOS.toByteArray()); //new FileInputStream(destinationFile));
                byte[] serverSideHash = BinaryUtils.fromHex(s3Object.getObjectMetadata().getETag());

                if (!Arrays.equals(clientSideHash, serverSideHash)) {
                    throw new AmazonClientException("Unable to verify integrity of data download.  "
                            + "Client calculated content hash didn't match hash calculated by Amazon S3.  "
                            + "The data may be corrupt; please try again.");
                }
            }
        } catch (Exception e) {
            log.warn("Unable to calculate MD5 hash to validate download: " + e.getMessage(), e);
        }

        try {
            eventualOutputStream.write(byteOS.toByteArray());
        } catch (Exception e) {

            log.warn("Unable to write to output stream: " + e.getMessage(), e);
        }
    }
}