/// <summary>
/// 生成请求时的签名
/// </summary>
/// <param name="sPara">请求给支付宝的参数数组</param>
/// <returns>签名结果</returns>
private string BuildRequestMysign(Dictionary <string, string> sPara)
{
//把数组所有元素，按照“参数=参数值”的模式用“&”字符拼接成字符串
string prestr = Core.CreateLinkString(sPara);
//把最终的字符串签名，获得签名结果
string mysign = "";
switch (_sign_type)
{
case "MD5":
mysign = AlipayMD5.Sign(prestr, _key, _input_charset);
break;
default:
mysign = "";
break;
}
return(mysign);
}