try
                {
                    WebClient client = new WebClient();
                    //client.QueryString.Add("account", "馮寶寶");
                    //client.QueryString.Add("password", "7777");
                    client.QueryString.Add("name", "馮寶寶");
                    client.Encoding = Encoding.UTF8;

                    client.Headers.Add(HttpRequestHeader.ContentType, "application/json");
                    //string result = client.UploadString("http://localhost:51151/Api/Users/Login", "");
                    string result = client.UploadString("http://localhost:51151/Api/Users/WithStringParamNoFromBody", "");
                }
                catch (Exception ex)
                {

                }
 

後端WebApi代碼如下：

 [AllowAnonymous]
        [HttpPost]
        public IEnumerable<Users> WithStringParamNoFromBody(string name)
        {
            return _userList;
        }

                 [AllowAnonymous]
        [HttpPost]
        public string Login(string account, string password)
        {
            if (account.Equals("馮寶寶") && password.Equals("7777"))
            {
                FormsAuthenticationTicket ticket = new FormsAuthenticationTicket(0,
                    account,
                    DateTime.Now,
                    DateTime.Now.AddMinutes(5),
                    true,
                    $"{account}&{password}",
                    FormsAuthentication.FormsCookiePath);
                var result = new { Result = true, Ticket = FormsAuthentication.Encrypt(ticket) };
                return JsonConvert.SerializeObject(result);
            }
            else
            {
                var result = new { Result = false };
                return JsonConvert.SerializeObject(result);
            }
        }
 

WebApi調用通用方法