code: private static byte[] sha256(String datas, String encoding) {
  		try {
  			return sha256(datas.getBytes(encoding));
  		} catch (UnsupportedEncodingException e) {
  			LogUtil.writeErrorLog("SHA256计算失败", e);
  			return null;
  		}
  	}
docs: sha256计算
  
  @param datas
  待计算的数据
  @param encoding
  字符集编码
  @return