在C＃中为亚马逊Web服务形成POST请求

Question

我正在尝试向amazons web api发送发布请求以从其接收xml。尝试进行设置时，出现400错误代码。

var request =（HttpWebRequest）WebRequest.Create（“ https://mws.amazonservices.com// ....”）;

        var postData = "AWSAccessKeyId=######&Action=ListOrders" +
            "&SellerId=######&MWSAuthToken=########&SignatureVersion=2" +
            "&Timestamp=####&Version=2013-09-01" +
            "&Signature=#########&SignatureMethod=####&CreatedAfter=###########&MarketplaceId.Id.1=#########";
        var data = Encoding.ASCII.GetBytes(postData);



        request.Method = "POST";
        request.ContentType = "application/x-www-form-urlencoded";
        request.ContentLength = data.Length;



        using (var stream = request.GetRequestStream())
        {
            stream.Write(data, 0, data.Length);
        }



        var response = (HttpWebResponse)request.GetResponse();



        var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();