該案例是mvc下的demo，支持單張圖片上傳。

 1 public ActionResult Upload()
 2         {
 3             string imgurl = "";
 4             foreach (string key in Request.Files)
 5             {
 6                 //這裏只測試上傳第一張圖片file[0]
 7                 HttpPostedFileBase file0 = Request.Files[key];
 8 
 9                 //
 
轉換成byte,讀取圖片MIME類型
10                 Stream stream;
11                 int size = file0.ContentLength / 1024; //文件大小KB
12 
13                 if (size > 1024)
14                 {
15                     return Content(ReturnMsg(Enum_Return.失敗, "圖片不能超過1M：", null));
16                 }
17 
18
 
                 byte[] fileByte = new byte[2];//contentLength，這裏我們只讀取文件長度的前兩位用於判斷就好了，這樣速度比較快，剩下的也用不到。
19                 stream = file0.InputStream;
20                 stream.Read(fileByte, 0, 2);//contentLength，還是取前兩位
21 
22                 //獲取圖片寬和高
23                 //System.Drawing.Image image = System.Drawing.Image.FromStream(stream);
 
24                 //int width = image.Width;
25                 //int height = image.Height;
26 
27 
28                 string fileFlag = "";
29                 if (fileByte != null && fileByte.Length > 0)//圖片數據是否為空
30                 {
31                     fileFlag = fileByte[0].ToString()   fileByte[1].ToString();
32                 }
33                 string[] fileTypeStr = { "255216", "7173", "6677", "13780" };//對應的圖片格式jpg,gif,bmp,png
34                 if (fileTypeStr.Contains(fileFlag))
35                 {
36                     string action = Request["action"];
37                     string path = "/uploads/";
38                     switch (action)
39                     {
40                         case "headimage":
41                             path    = "headimage/";
42                             break;
43                         case "blogtype":
44                             path    = "blogtype/";
45                             break;
46                     }
47                     string fullpath = path    UserInfo.userID    "/";
48                     if (!Directory.Exists(Server.MapPath(fullpath)))
49                     {
50                         Directory.CreateDirectory(Server.MapPath(fullpath));
51                     }
52 
53 
54                     Request.Files[key].SaveAs(Server.MapPath(fullpath   Request.Files[key].FileName));
55                     imgurl = fullpath    Request.Files[key].FileName;
56                 }
57                 else
58                 {
59                     return Content(ReturnMsg(Enum_Return.失敗, "圖片格式不正確："  fileFlag, null));
60                 }
61 
62                 stream.Close();
63             }
64 
65             return Content(ReturnMsg(Enum_Return.成功, "上傳成功", imgurl));
66         }

一般處理程序

public void ProcessRequest(HttpContext context)
    {
        context.Response.ContentType = "application/json";
        HttpPostedFile _upfile = context.Request.Files["File"];
        if (_upfile.ContentLength < 500000)
        {
            if (string.IsNullOrEmpty(_upfile.FileName))
            {
                 context.Response.Write("請上傳圖片");
            }
            string fileFullname = _upfile.FileName;
            string dataName = DateTime.Now.ToString("yyyyMMddhhmmss");
            string fileName = fileFullname.Substring(fileFullname.LastIndexOf("\\")    1);
            string type = fileFullname.Substring(fileFullname.LastIndexOf(".")    1);
            if (type == "bmp" || type == "jpg" || type == "gif" || type == "JPG" || type == "BMP" || type == "GIF")
            {
                _upfile.SaveAs(HttpContext.Current.Server.MapPath("photo")   "\\"    dataName    "."    type);
                HttpCookie cookie = new HttpCookie("photo");
                context.Response.Write("上傳成功");
            }
            else
            {
                context.Response.Write("支持格式：|jpg|gif|bmp|");
            }
        }
        else
        {
            context.Response.Write("你的圖片已經超過500K的大小！");
        }
    }

.Net MVC 圖片上傳