| /* |
| * Copyright (C) 2017 The Android Open Source Project |
| * |
| * 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://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 android.util; |
| |
| /** |
| * A utility class for common byte array to hex string operations and vise versa. |
| * |
| * @hide |
| */ |
| public final class ByteStringUtils { |
| private static final char[] HEX_LOWERCASE_ARRAY = "0123456789abcdef".toCharArray(); |
| private static final char[] HEX_UPPERCASE_ARRAY = "0123456789ABCDEF".toCharArray(); |
| |
| private ByteStringUtils() { |
| /* hide constructor */ |
| } |
| |
| /** |
| * Returns the hex encoded string representation of bytes. |
| * @param bytes Byte array to encode. |
| * @return Hex encoded string representation of bytes. |
| */ |
| public static String toHexString(byte[] bytes) { |
| if (bytes == null || bytes.length == 0 || bytes.length % 2 != 0) { |
| return null; |
| } |
| |
| final int byteLength = bytes.length; |
| final int charCount = 2 * byteLength; |
| final char[] chars = new char[charCount]; |
| |
| for (int i = 0; i < byteLength; i++) { |
| final int byteHex = bytes[i] & 0xFF; |
| chars[i * 2] = HEX_UPPERCASE_ARRAY[byteHex >>> 4]; |
| chars[i * 2 + 1] = HEX_UPPERCASE_ARRAY[byteHex & 0x0F]; |
| } |
| return new String(chars); |
| } |
| |
| /** |
| * Returns the decoded byte array representation of str. |
| * @param str Hex encoded string to decode. |
| * @return Decoded byte array representation of str. |
| */ |
| public static byte[] fromHexToByteArray(String str) { |
| if (str == null || str.length() == 0 || str.length() % 2 != 0) { |
| return null; |
| } |
| |
| final char[] chars = str.toCharArray(); |
| final int charLength = chars.length; |
| final byte[] bytes = new byte[charLength / 2]; |
| |
| for (int i = 0; i < bytes.length; i++) { |
| bytes[i] = |
| (byte) (((getIndex(chars[i * 2]) << 4) & 0xF0) |
| | (getIndex(chars[i * 2 + 1]) & 0x0F)); |
| } |
| return bytes; |
| } |
| |
| private static int getIndex(char c) { |
| for (int i = 0; i < HEX_UPPERCASE_ARRAY.length; i++) { |
| if (HEX_UPPERCASE_ARRAY[i] == c || HEX_LOWERCASE_ARRAY[i] == c) { |
| return i; |
| } |
| } |
| return -1; |
| } |
| } |