• • 编辑1：**

似乎是HTTPClient的一些限制，我终于为自己解决了一个问题，以下是我的建议：
1.更改服务合同中的UriTemplate：

[WebInvoke(UriTemplate = "Inventory", Method = "POST")]
public InventoryResponse Post(InventoryRequest inventoryRequest)

1.将终结点地址更改为

http://localhost

1.再次尝试使用HTTPClient访问该服务：

using (var client = new HttpClient())
{
    var postUri= "http://localhost/";
    client.BaseAddress = new Uri(postUri);
    client.DefaultRequestHeaders.Accept.Clear();
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

    inventoryResponse = client.PostAsJsonAsync("Inventory", inventoryRequest).Result.Content.ReadAsAsync<InventoryResponse>().Result;

}

最后，它应该起作用了。

• • 上一个答案：**

您的客户端没有发送正确的请求，服务器期望xml，但客户端发送了其他内容（似乎是json，内容类型是文本）。
1.您可以使用稍有不同的方式在客户端上进行调用：在客户端库中引用服务接口和数据契约（不应该有服务实现，但如果是为了测试，也可以），并将代码替换为：

ChannelFactory<YourServiceInterface> myChannelFactory = new ChannelFactory<YourServiceInterface>("MyService"); //MyServive clinet endpoint name

// Create a channel.
YourServiceInterface wcfClient1 = myChannelFactory.CreateChannel();
var resp = wcfClient1.Post(inventoryRequest);

((IClientChannel)wcfClient1).Close();

如果你关心异步操作，你可以用TPL，用一个任务

1. Fiddler有一个选项可以捕获来自其他客户端的每个请求。这样做并向我们发送请求和响应的内容。
   1.这肯定是你的客户端有问题。你可以试试这个代码，它必须工作（它为我工作，我已经检查）：

public class WebRequestor
{
    public void MakeCall(DividendEvents dividends, Uri uri)
    {
        var postData = Serialize(dividends);
        var request = FormWebRequest(postData, uri);

        var response = request.GetResponse();

        Console.WriteLine(((HttpWebResponse)response).StatusDescription);
        var dataStream = response.GetResponseStream();
        var reader = new StreamReader(dataStream);

        // Read the content of response, if you need to have to deserialize it (in the same way as Serialize method does serialization)
        string responseFromServer = reader.ReadToEnd();

        reader.Close();
        dataStream.Close();
        response.Close();
    }

    private static WebRequest FormWebRequest(string postData, Uri uri)
    {
        WebRequest request = WebRequest.Create(uri);
        request.Method = "POST";
        request.ContentType = "application/json";

        byte[] byteArray = Encoding.UTF8.GetBytes(postData);
        request.ContentLength = byteArray.Length;
        // Get the request stream.
        Stream dataStream = request.GetRequestStream();
        // Write the data to the request stream.
        dataStream.Write(byteArray, 0, byteArray.Length);
        // Close the Stream object.
        dataStream.Close();
        return request;
    }

    private static string Serialize(object data)
    {
        var stream1 = new MemoryStream();
        var testSer = new DataContractJsonSerializer(data.GetType());
        testSer.WriteObject(stream1, data);
        stream1.Seek(0, SeekOrigin.Begin);
        var sreader = new StreamReader(stream1);
        var cont = sreader.ReadToEnd();
        return cont;
    }
}

下面是实际调用：

var div = new DividendEvents() {Events = new[] {1, 2, 3}, Id = "GOOGL"};
        new WebRequestor().MakeCall(div, new Uri("http://localhost:9002/Pricing/Dividends"));