com.glaf.core.util.BinaryUtils.java Source code

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Here is the source code for com.glaf.core.util.BinaryUtils.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License 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.glaf.core.util;

import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.Locale;

import org.apache.commons.codec.binary.Base64;

/**
 * Utilities for encoding and decoding binary data to and from different forms.
 */
public class BinaryUtils {
    /**
     * 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) {
        return Base64.encodeBase64String(data);
    }

    /**
     * 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 b64Data == null ? null : Base64.decodeBase64(b64Data);
    }

    /**
     * Returns a copy of all the bytes from the given <code>ByteBuffer</code>,
     * from the beginning to the buffer's limit; or null if the input is null.
     * <p>
     * The internal states of the given byte buffer will be restored when this
     * method completes execution.
     * <p>
     * When handling <code>ByteBuffer</code> from user's input, it's typical to
     * call the {@link #copyBytesFrom(ByteBuffer)} instead of
     * {@link #copyAllBytesFrom(ByteBuffer)} so as to account for the position
     * of the input <code>ByteBuffer</code>. The opposite is typically true,
     * however, when handling <code>ByteBuffer</code> from withint the
     * unmarshallers of the low-level clients.
     */
    public static byte[] copyAllBytesFrom(ByteBuffer bb) {
        if (bb == null)
            return null;
        if (bb.hasArray())
            return Arrays.copyOf(bb.array(), bb.limit());
        bb.mark();
        // the default ByteBuffer#mark() and reset() won't work, as the
        // rewind would discard the mark position
        final int marked = bb.position();
        try {
            byte[] dst = new byte[bb.rewind().remaining()];
            bb.get(dst);
            return dst;
        } finally {
            bb.position(marked);
        }
    }

    /**
     * Returns a copy of the bytes from the given <code>ByteBuffer</code>,
     * ranging from the the buffer's current position to the buffer's limit; or
     * null if the input is null.
     * <p>
     * The internal states of the given byte buffer will be restored when this
     * method completes execution.
     * <p>
     * When handling <code>ByteBuffer</code> from user's input, it's typical to
     * call the {@link #copyBytesFrom(ByteBuffer)} instead of
     * {@link #copyAllBytesFrom(ByteBuffer)} so as to account for the position
     * of the input <code>ByteBuffer</code>. The opposite is typically true,
     * however, when handling <code>ByteBuffer</code> from withint the
     * unmarshallers of the low-level clients.
     */
    public static byte[] copyBytesFrom(ByteBuffer bb) {
        if (bb == null)
            return null;
        if (bb.hasArray())
            return Arrays.copyOfRange(bb.array(), bb.position(), bb.limit());
        bb.mark();
        try {
            byte[] dst = new byte[bb.remaining()];
            bb.get(dst);
            return dst;
        } finally {
            bb.reset();
        }
    }
}