对于JSON Post:

var stringContent = new StringContent(json, Encoding.UTF8, "application/json");
var response = await httpClient.PostAsync("http://www.sample.com/write", stringContent);

Non-JSON:

var stringContent = new FormUrlEncodedContent(new[]
{
    new KeyValuePair<string, string>("field1", "value1"),
    new KeyValuePair<string, string>("field2", "value2"),
});
var response = await httpClient.PostAsync("http://www.sample.com/write", stringContent);

https://blog.pedrofelix.org/2012/01/16/the-new-system-net-http-classes-message-content/

只使用……

var stringContent = new StringContent(jObject.ToString());
var response = await httpClient.PostAsync("http://www.sample.com/write", stringContent);

Or,

var stringContent = new StringContent(JsonConvert.SerializeObject(model), Encoding.UTF8, "application/json");
var response = await httpClient.PostAsync("http://www.sample.com/write", stringContent);

要获取6footunder的注释并将其转换为答案，HttpContent是抽象的，所以你需要使用一个派生类:

就用微软。aspnet。webapi。client吧。

例子:

var client = HttpClientFactory.Create();
var result = await client.PostAsync<ExampleClass>("http://www.sample.com/write", new ExampleClass(), new JsonMediaTypeFormatter());

对于JSON Post:

var stringContent = new StringContent(json, Encoding.UTF8, "application/json");
var response = await httpClient.PostAsync("http://www.sample.com/write", stringContent);

Non-JSON:

var stringContent = new FormUrlEncodedContent(new[]
{
    new KeyValuePair<string, string>("field1", "value1"),
    new KeyValuePair<string, string>("field2", "value2"),
});
var response = await httpClient.PostAsync("http://www.sample.com/write", stringContent);

https://blog.pedrofelix.org/2012/01/16/the-new-system-net-http-classes-message-content/

我非常确定代码没有使用System.Net.Http.HttpContent类，而是使用Microsoft.Http.HttpContent。 微软。Http是WCF REST入门套件，它在被放入。net框架之前从未发布过预览版。 你仍然可以在这里找到它:http://aspnet.codeplex.com/releases/view/24644

我不建议在此基础上编写新代码。