img src="Handler.ashx?PhotoID=<%# Eval("PhotoID") %>&Size=S"

很奇怪的事情，只是发现了，但不明白为什么！

Handler
 1<%@ WebHandler Language="C#" Class="Handler" %>
 2
 3using System;
 4using System.IO;
 5using System.Web;
 6
 7public class Handler : IHttpHandler {
 8
 9    public bool IsReusable {
10        get {
11            return true;
12        }
13    }
14    
15    public void ProcessRequest (HttpContext context) {
16        // Set up the response settings
17        context.Response.ContentType = "image/jpeg";
18        context.Response.Cache.SetCacheability(HttpCacheability.Public);
19        context.Response.BufferOutput = false;
20        // Setup the Size Parameter
21        PhotoSize size;
22        switch (context.Request.QueryString["Size"]) {
23            case "S":
24                size = PhotoSize.Small;
25                break;
26            case "M":
27                size = PhotoSize.Medium;
28                break;
29            case "L":
30                size = PhotoSize.Large;
31                break;
32            default:
33                size = PhotoSize.Original;
34                break;
35        } 
36        // Setup the PhotoID Parameter
37        Int32 id = -1;
38        Stream stream = null;
39        if (context.Request.QueryString["PhotoID"] != null && context.Request.QueryString["PhotoID"] != "") {
40            id = Convert.ToInt32(context.Request.QueryString["PhotoID"]);
41            stream = PhotoManager.GetPhoto(id, size);
42        } else {
43            id = Convert.ToInt32(context.Request.QueryString["AlbumID"]);
44            stream = PhotoManager.GetFirstPhoto(id, size);
45        }
46        // Get the photo from the database, if nothing is returned, get the default "placeholder" photo
47        if (stream == null) stream = PhotoManager.GetPhoto(size);
48        // Write image stream to the response stream
49        const int buffersize = 1024 * 16;
50        byte[] buffer = new byte[buffersize];
51        int count = stream.Read(buffer, 0, buffersize);
52        while (count > 0) {
53            context.Response.OutputStream.Write(buffer, 0, count);
54            count = stream.Read(buffer, 0, buffersize);
55        }
56    }
57
58}

据说是能以流的方式直接读取存在数据库中的图片。