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The Amazon Web Services SDK for Java provides Java APIs for building software on AWS' cost-effective, scalable, and reliable infrastructure products. The AWS Java SDK allows developers to code against APIs for all of Amazon's infrastructure web services (Amazon S3, Amazon EC2, Amazon SQS, Amazon Relational Database Service, Amazon AutoScaling, etc).

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/*
 * Copyright 2010-2014 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Portions copyright 2006-2009 James Murty. Please see LICENSE.txt
 * for applicable license terms and NOTICE.txt for applicable notices.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. 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.util;

import static com.amazonaws.util.StringUtils.UTF8;

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.util.Locale;

import org.apache.commons.codec.binary.Base64;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Utilities for encoding and decoding binary data to and from different forms.
 */
public class BinaryUtils {

    private static final Log log = LogFactory.getLog(BinaryUtils.class);

    /**
     * Converts byte data to a Hex-encoded string.
     *
     * @param data
     *            data to hex encode.
     *
     * @return hex-encoded string.
     */
    public static String toHex(byte[] data) {
        StringBuilder sb = new StringBuilder(data.length * 2);
        for (int i = 0; i < data.length; i++) {
            String hex = Integer.toHexString(data[i]);
            if (hex.length() == 1) {
                // Append leading zero.
                sb.append("0");
            } else if (hex.length() == 8) {
                // Remove ff prefix from negative numbers.
                hex = hex.substring(6);
            }
            sb.append(hex);
        }
        return sb.toString().toLowerCase(Locale.getDefault());
    }

    /**
     * Converts a Hex-encoded data string to the original byte data.
     *
     * @param hexData
     *            hex-encoded data to decode.
     * @return decoded data from the hex string.
     */
    public static byte[] fromHex(String hexData) {
        byte[] result = new byte[(hexData.length() + 1) / 2];
        String hexNumber = null;
        int stringOffset = 0;
        int byteOffset = 0;
        while (stringOffset < hexData.length()) {
            hexNumber = hexData.substring(stringOffset, stringOffset + 2);
            stringOffset += 2;
            result[byteOffset++] = (byte) Integer.parseInt(hexNumber, 16);
        }
        return result;
    }

    /**
     * Converts byte data to a Base64-encoded string.
     *
     * @param data
     *            data to Base64 encode.
     * @return encoded Base64 string.
     */
    public static String toBase64(byte[] data) {
        byte[] b64 = Base64.encodeBase64(data);
        return new String(b64);
    }

    /**
     * Converts a Base64-encoded string to the original byte data.
     *
     * @param b64Data
     *            a Base64-encoded string to decode.
     *
     * @return bytes decoded from a Base64 string.
     */
    public static byte[] fromBase64(String b64Data) {

        return Base64.decodeBase64(b64Data.getBytes(UTF8));
    }

    /**
     * Wraps a ByteBuffer in an InputStream.
     *
     * @param byteBuffer The ByteBuffer to wrap.
     *
     * @return An InputStream wrapping the ByteBuffer content.
     */
    public static InputStream toStream(ByteBuffer byteBuffer) {
        byte[] bytes = new byte[byteBuffer.remaining()];
        byteBuffer.get(bytes);
        return new ByteArrayInputStream(bytes);
    }

}