code: public static String hmacSHA256(String stringSignTemp, String partnerKey)  throws UnsupportedEncodingException, NoSuchAlgorithmException, InvalidKeyException {
  		Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
  		SecretKeySpec secret_key = new SecretKeySpec(partnerKey.getBytes(), "HmacSHA256");
  		sha256_HMAC.init(secret_key);
  		return byteArrayToHexString(sha256_HMAC.doFinal(stringSignTemp.getBytes("utf-8")));
  	}
docs: HmacSHA256 签名
  @param stringSignTemp
  @param partnerKey
  @return
  @throws Exception