Java实现byte数组与Hex互转

十六进制字符的输出大写字符：0123456789ABCDEF
十六进制字符的输出小写字符：0123456789abcdef

下面使用十六进制大写字符。

1、方式1

public class HexStringUtils {private static final char[] HEX_CHAR_TABLE = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};private static final Map<Character, Byte> HEX_BYTE_MAP = new HashMap<>();static {for (int i = 0; i < HEX_CHAR_TABLE.length; i++) {char c = HEX_CHAR_TABLE[i];HEX_BYTE_MAP.put(c, (byte) i);}}/*** 将byte数组转换为表示16进制值的字符串** @param byteArray 需要转换的byte数组* @return 转换后的字符串（16进制值）*/public static String byteArrayToHexString(byte[] byteArray) {if (byteArray == null) {return null;}StringBuilder sb = new StringBuilder();for (byte b : byteArray) {sb.append(HEX_CHAR_TABLE[(b & 0xf0) >> 4]);sb.append(HEX_CHAR_TABLE[b & 0x0f]);}return sb.toString();}/*** 将表示16进制值的字符串转换为byte数组** @param hexString 需要转换的字符串（16进制值）* @return 转换后的byte数组*/public static byte[] hexStringToByteArray(String hexString) {if (StringUtils.isBlank(hexString)) {return null;}// 两个字符表示一个字节，所以字节数组长度是字符串长度除以2byte[] byteArray = new byte[hexString.length() / 2];for (int i = 0; i < hexString.length() / 2; i++) {char hi = hexString.charAt(i * 2);char lo = hexString.charAt(i * 2 + 1);byteArray[i] = (byte) ((HEX_BYTE_MAP.get(hi) << 4) + HEX_BYTE_MAP.get(lo));}return byteArray;}public static void main(String[] args) {String str = "你好 asa;==ff--00=-=";//String hexString = byteArrayToHexString(str.getBytes());System.out.println(str.length());System.out.println(hexString);System.out.println(hexString.length());System.out.println("===========");byte[] bytes = hexStringToByteArray(hexString);System.out.println(Arrays.toString(bytes));System.out.println(new String(bytes));}
}

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2、方式2

public class HexStringUtils {public static byte[] hexStringToByteArray(String hexString) {if (StringUtils.isEmpty(hexString)) {return null;}hexString = hexString.toLowerCase();final byte[] byteArray = new byte[hexString.length() >> 1];int index = 0;for (int i = 0; i < hexString.length(); i++) {if (index > hexString.length() - 1) {return byteArray;}byte highDit = (byte) (Character.digit(hexString.charAt(index), 16) & 0xFF);byte lowDit = (byte) (Character.digit(hexString.charAt(index + 1), 16) & 0xFF);byteArray[i] = (byte) (highDit << 4 | lowDit);index += 2;}return byteArray;}public static String byteArrayToHexString(byte[] byteArray) {if (byteArray == null) {return null;}// HEX_CHAR_TABLE  0123456789abcdefchar[] hexArray = "0123456789ABCDEF".toCharArray();char[] hexChars = new char[byteArray.length * 2];for (int j = 0; j < byteArray.length; j++) {int v = byteArray[j] & 0xFF;hexChars[j * 2] = hexArray[v >>> 4];hexChars[j * 2 + 1] = hexArray[v & 0x0F];}return new String(hexChars);}public static void main(String[] args) {String str = "你好 asa;==ff--00=-=";//String hexString = byteArrayToHexString(str.getBytes());System.out.println(str.length());System.out.println(hexString);System.out.println(hexString.length());System.out.println("===========");byte[] bytes = hexStringToByteArray(hexString);System.out.println(Arrays.toString(bytes));System.out.println(new String(bytes));}}