//webclient应用
 MyImageServerEntities db = new MyImageServerEntities();

        public ActionResult Index()

        {

            return View();

        }

        public ActionResult FileUpload()

        {

            HttpPostedFileBase file = Request.Files["fileUp"];

            string fileName = Path.GetFileName(file.FileName);

            string fileExt = Path.GetExtension(fileName);

            if (fileExt == ".jpg")

            {

              var list=db.ImageServerInfo.Where<ImageServerInfo>(u => u.FlgUsable == true).ToList();//找出可用的图片服务器.

              int count = list.Count();

              Random random = new Random();

              int r = random.Next();

              int i = r % count;

              string serverUrl = list[i].ServerUrl;

              int serverId = list[i].ServerId;

              string url = "http://"+serverUrl+"/FileUp.ashx?serverId="+serverId+"&fileExt="+fileExt;

              WebClient webClient =new WebClient();

              webClient.UploadData(url, StreamToBytes(file.InputStream));

            }

            return Content("ok");

        }

        public ActionResult ShowImage()

        {

          var list=  db.ImageServerInfo.Where<ImageServerInfo>(c=>c.FlgUsable==true).ToList();

          ViewData["imageServerList"] = list;

          return View();

        }

        private byte[] StreamToBytes(Stream stream)

        {

            byte[]buffer=new byte[stream.Length];

            stream.Read(buffer, , buffer.Length);

            stream.Seek(, SeekOrigin.Begin);

            return buffer;

        }

           context.Response.ContentType = "text/plain";

            int serverId = int.Parse(context.Request["serverId"]);

            string fileExt = context.Request["fileExt"];

            string dir = "/ImagePath/" + DateTime.Now.Year + "/" + DateTime.Now.Month + "/" + DateTime.Now.Day + "/";

            Directory.CreateDirectory(Path.GetDirectoryName(context.Request.MapPath(dir)));

            string newfileName = Guid.NewGuid().ToString();

            string fullDir = dir + newfileName + fileExt;

            using (FileStream fileStream = File.Open(context.Request.MapPath(fullDir), FileMode.OpenOrCreate))

            {

                context.Request.InputStream.CopyTo(fileStream);

                MyImageServerEntities db = new MyImageServerEntities();

                ImageInfo imageInfo = new ImageInfo();

                imageInfo.ImageName = fullDir;

                imageInfo.ImageServerId = serverId;

                db.ImageInfo.Add(imageInfo);

                db.SaveChanges();

            }

创建并初始化对象：

    client.BaseAddress = new Uri(url);

    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

读集合：

    HttpResponseMessage response = client.GetAsync(url).Result;

     var userList = response.Content.ReadAsAsync<IEnumerable<数据类型>>().Result;

根据编号读对象

    HttpResponseMessage response1 = client.GetAsync(url).Result;

    var userInfo = response1.Content.ReadAsAsync<数据类型>().Result;

增加：

    HttpResponseMessage response = client.PostAsJsonAsync("api/userinfo", userInfo).Result;

    使用response.IsSuccessStatusCode判断是否成功

    使用response.Content.ToString()获取返回值

修改：

     HttpResponseMessage response = client.PutAsJsonAsync("api/userinfo/"+userInfo.UserId, userInfo).Result;

    使用response.IsSuccessStatusCode判断是否成功

    使用response.Content.ToString()获取返回值

删除：

    HttpResponseMessage response = client.DeleteAsync("api/userinfo/" + uid).Result;

    使用response.IsSuccessStatusCode判断是否成功

    使用response.Content.ToString()获取返回值