code: public static byte[] fromHexString(String value) {
      byte[] rs = new byte[value.length() / 2];
      for (int i = 0; i < value.length(); i += 2) {
        String b = value.substring(i, i + 2);
        rs[i / 2] = Integer.valueOf(b, 16).byteValue();
      }
      return rs;
    }
docs: 16进制显示数据
  
  @param value
  字节数组