定义无图片时显示默认图片，大小

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="ImageThumbnail.ascx.cs" Inherits="ImageThumbnail" %>

<asp:Image ID="Image1" runat="server" CssClass="photo" BorderWidth="1" />
1using System;

2

3public partial class ImageThumbnail : System.Web.UI.UserControl

4
ImageFetch.ashx
1<%@ WebHandler Language="C#" Class="ImageFetch" %>

2

3using System;

4using System.Web;

5using System.Data.SqlClient;

6using System.Data;

7using System.IO;

8

9public class ImageFetch : IHttpHandler

10{

11 const int BUFFERSIZE = 1024;

12

13 public bool IsReusable

14 {

15 get

16 {

17 return true;

18 }

19 }

20

21 public void ProcessRequest(HttpContext context)

22 {

23 HttpResponse response = context.Response;

24 HttpRequest request = context.Request;

25 response.ContentType = "image/jpeg";

26 response.Cache.SetCacheability(HttpCacheability.Public);

27 response.BufferOutput = false;

28 writeSingleImage(Convert.ToInt32(request.QueryString["ImageID"]), Convert.ToInt32(request.QueryString["Size"]), response.OutputStream);

29 response.End();

30 }

31

32 public void writeSingleImage(int ImageID, int size, Stream output)

33 {

34 string cxnstr = System.Configuration.ConfigurationManager.ConnectionStrings["ClubSiteDB"].ConnectionString;

35 SqlConnection connection = new SqlConnection(cxnstr);

36 string query;

37 if (size == 0)

38 {

39 query = "select largeimage from images where id=@item_id";

40 }

41 else if (size == 1)

42 {

43 query = "select thumbimage from images where id=@item_id";

44 }

45 else if (size == 2)

46 {

47 query = "select origimage from images where id=@item_id";

48 }

49 else

50 {

51 query = "select largeimage from images where id=@item_id";

52 }

53 SqlCommand command = new SqlCommand(query, connection);

54 SqlParameter param0 = new SqlParameter("@item_id", SqlDbType.Int);

55 param0.Value = ImageID;

56 command.Parameters.Add(param0);

57 connection.Open();

58

59 byte[] d = ((byte[])(command.ExecuteScalar()));

60 output.Write(d, 0, d.Length);

61 connection.Close();

62 }

63}