HttpClient client = new HttpClient();

 client.BaseAddress = new Uri("http://localhost:9000/");

 // Add an Accept header for JSON format.

 // 为JSON格式添加一个Accept报头

 client.DefaultRequestHeaders.Accept.Add(

                new MediaTypeWithQualityHeaderValue("application/json")); 

var response = client.GetAsync("api/GetEmployees").Result; //转换为同步方法

if (response.IsSuccessStatusCode) //请求成功

{

   //从方法名中可以看出是异步调用，取Result后，就变成同步了，

    var results = response.Content.ReadAsAsync<IEnumerable<Employee>>().Result;

    foreach (var p in results)

    {

        Console.WriteLine("{0}\t{1};\t{2}", p.Name, p.Age, p.Sex);

    }

}

else

{

    Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);

}

using System.Net.Http;

using System.Net.Http.Headers;

//api 为  http://localhost:8000/Employee/Update

  //传入参数 name,age,sex

        HttpClient client = new HttpClient();

        public override bool SendMessage()

        {

            client.DefaultRequestHeaders.Accept.Add(

                new MediaTypeWithQualityHeaderValue("application/json"));

            var paras= new { name ="", age =,sex="男" };

            try

            {

                var response = client.PostAsJsonAsync(" http://localhost:8000/Employee/Update", paras).Result;

                 //如果调用失败，抛出异常

                response.EnsureSuccessStatusCode();

                if (response.IsSuccessStatusCode)

                {

                    var result = response.Content.ReadAsStringAsync();

                  //result.Result 是一个json字符串,解析后就可以拿到调用后的返回值

                    return false;

                }

                else

                {

                    return false;

                }

            }

            catch (Exception ex)

            {

                return false;

            }

            return true;

        }