[C#][WebAPI]返回 json

//将webapi的返回值设为Json格式
var jsonFormatter = new JsonMediaTypeFormatter();
GlobalConfiguration.Configuration.Services.Replace(typeof(IContentNegotiator), new JsonContentNegotiator(jsonFormatter));

// ---- 或者这样：
config.Formatters.JsonFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/html"));
  

 客户端调用的方式为：

var web = "http://weburl/api";
var request = WebRequest.Create(web);
request.ContentType = "application/json";
request.Method = "Post";

string json = JsonConvert.SerializeObject(new
{
    Arg1 = "arg1"
});
using (var sw = new StreamWriter(request.GetRequestStream()))
{
    sw.Write(json);
}
var response = request.GetResponse();
using (var sr = new StreamReader(response.GetResponseStream()))
{
    var str = sr.ReadToEnd();
    try
    {
        var obj = JsonConvert.DeserializeObject<object>(str);
        if (obj != null)
        {
            if (obj.errorCode == 0)
            {
                return obj.data;
            }
            else
            {
                msg = obj.message;
            }
        }
    }
    catch (Exception ex)
    {
        msg = string.Format("错误：{0}", ex.Message);
    }
}
return msg;