code: public static byte[] hex2byte(String hex) {
  		byte[] ret = new byte[8];
  		byte[] tmp = hex.getBytes();
  		for (int i = 0; i < 8; i++) {
  			ret[i] = uniteBytes(tmp[i * 2], tmp[i * 2 + 1]);
  		}
  		return ret;
  	}
docs: 十六进制字符串转化为2进制
  
  @param hex
  @return