code: private static String byte2hex(byte[] b) {
  		StringBuilder hs = new StringBuilder();
  		String stmp;
  		for (int n = 0; b!=null && n < b.length; n++) {
  			stmp = Integer.toHexString(b[n] & 0XFF);
  			if (stmp.length() == 1)
  				hs.append('0');
  			hs.append(stmp);
  		}
  		return hs.toString().toUpperCase();
  	}
docs: 二行制转字符串
  @param b
  @return