C# Webapi中需要JSON/XML数据

当我请求一个webapi请求时，我得到了一个错误，比如需要JSON/XML数据

try         
{                
    string oRequest = _xml.UpdateInvereqxml(UserName, Password,OTAhotelid, Invy);                
    string uri = @"service/update";
    System.Net.WebRequest req = System.Net.WebRequest.Create(uri);
    req.Method = "POST";
    req.ContentType = "text/xml";
    System.IO.StreamWriter writer = new System.IO.StreamWriter(req.GetRequestStream());
    writer.WriteLine(oRequest);
    writer.Close();
    System.Net.WebResponse rsp = req.GetResponse();
    Stream istrm = rsp.GetResponseStream();
    string StreamReader = new StreamReader(istrm).ReadToEnd();
}

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我建议使用HttpClient与ASP.NET Web API通信。该类提供了许多使用REST服务（）的函数

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如何解决上述错误？可能是服务器引发了异常，因为您发送了错误的内容类型。或者可能您缺少正确的接受标题

public EnumProduct Post(EnumProduct product)
{
HttpResponseMessage reponse = httpClient.PostAsJsonAsync("api/enumproducts/Post", product).Result;
if (reponse.IsSuccessStatusCode)
{
var enumProduct = reponse.Content.ReadAsAsync().Result;
return enumProduct;
}
else
return null;
}