在javacard中将十六进制字符串转换为字节数组

public byte[] hexStringToByteArray(String hexString) {
    char[] hexChars = hexString.toCharArray();
    
    // 如果字符数组长度为奇数，则在前面添加一个'0'字符
    if (hexChars.length % 2 != 0) {
        hexChars = Arrays.copyOf(hexChars, hexChars.length + 1);
        hexChars[hexChars.length - 1] = '0';
    }
    
    byte[] byteArray = new byte[hexChars.length / 2];
    
    for (int i = 0; i < hexChars.length; i += 2) {
        int highNibble = Character.digit(hexChars[i], 16);
        int lowNibble = Character.digit(hexChars[i + 1], 16);
        byteArray[i / 2] = (byte) ((highNibble << 4) + lowNibble);
    }
    
    return byteArray;
}