.NET HttpClient请求内容类型

您应该设置内容类型。使用“接受”可以定义要作为响应的内容。

http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html 接受请求标头字段可用于指定响应可接受的某些媒体类型。接受标头可用于指示该请求特别限于一小部分所需类型，例如在请求嵌入式图像的情况下。

public async Task SendPost(Model model)
{
    var client = new HttpClient(); //You should extract this and reuse the same instance multiple times.
    var request = new HttpRequestMessage(HttpMethod.Post, Url + "api/foo");
    using(var content = new StringContent(Serialize(model), Encoding.UTF8, "application/json"))
    {
        request.Content = content;
        var response = await client.SendAsync(request).ConfigureAwait(false);
        response.EnsureSuccessStatusCode();
        return await response.Content.ReadAsStringAsync().ConfigureAwait(false);
    }
}