.NET MVC4 用HttpClient后台post 请求webapi

public ActionResult Index()
{
var requestJson = JsonConvert.SerializeObject("[{'CityId':18,'CityName':'西安','ProvinceId':27,'CityOrder':1},{'CityId':53,'CityName':'广州','ProvinceId':27,'CityOrder':1}]");
HttpContent httpContent = new StringContent(requestJson);
httpContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
var httpClient = new HttpClient();
var responseJson = httpClient.PostAsync("http://localhost:6972/api/test/Post/", httpContent)
.Result.Content.ReadAsStringAsync().Result;

ViewBag.s = responseJson;
return View();
}

// POST api/values
public HttpResponseMessage Post([FromBody]string value)
{
return Request.CreateResponse(HttpStatusCode.OK, value);
}