Personal Web Site--Custom handler for fetching images from a database

1.数据库设计
字段              类型
PhotoID          int
AlbumID         int
Caption           nvarchar(50)
BytesOriginal   image
BytesFull         image
BytesPoster     image
BytesThumb    image

2.前台显示图片

<img src="Handler.ashx?AlbumID=<%# Eval("AlbumID") %>&Size=M" class="photo_198" style="border:4px solid white" alt='示例照片，相册编号 <%# Eval("AlbumID") %>' />

3.Handler.ashx

<%@ WebHandler Language="C#" Class="Handler" %>

using System;
using System.IO;
using System.Web;

public class Handler : IHttpHandler {

    public bool IsReusable {
        get {
            return true;
        }
    }
    
    public void ProcessRequest (HttpContext context) {
        // 设置响应设置
        context.Response.ContentType = "image/jpeg";
        context.Response.Cache.SetCacheability(HttpCacheability.Public);
        context.Response.BufferOutput = false;
        // 设置 Size 参数
        PhotoSize size;
        switch (context.Request.QueryString["Size"]) {
            case "S":
                size = PhotoSize.Small;
                break;
            case "M":
                size = PhotoSize.Medium;
                break;
            case "L":
                size = PhotoSize.Large;
                break;
            default:
                size = PhotoSize.Original;
                break;
        } 
        // 设置 PhotoID 参数
        Int32 id = -1;
        Stream stream = null;
        if (context.Request.QueryString["PhotoID"] != null && context.Request.QueryString["PhotoID"] != "") {
            id = Convert.ToInt32(context.Request.QueryString["PhotoID"]);
            stream = PhotoManager.GetPhoto(id, size);
        } else {
            id = Convert.ToInt32(context.Request.QueryString["AlbumID"]);
            stream = PhotoManager.GetFirstPhoto(id, size);
        }
        // 从数据库获取照片，如果未返回照片，将获取默认的“placeholder”照片
        if (stream == null) stream = PhotoManager.GetPhoto(size);
        // 将图像流写入响应流中
        const int buffersize = 1024 * 16;
        byte[] buffer = new byte[buffersize];
        int count = stream.Read(buffer, 0, buffersize);
        while (count > 0) {
            context.Response.OutputStream.Write(buffer, 0, count);
            count = stream.Read(buffer, 0, buffersize);
        }
    }

}

 

4.业务层类（PhotoManager 部分内容）

    public static List<Photo> GetPhotos(int AlbumID) {
        using (SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["Personal"].ConnectionString)) {
            using (SqlCommand command = new SqlCommand("GetPhotos", connection)) {
                command.CommandType = CommandType.StoredProcedure;
                command.Parameters.Add(new SqlParameter("@AlbumID", AlbumID));
                bool filter = !(HttpContext.Current.User.IsInRole("Friends") || HttpContext.Current.User.IsInRole("Administrators"));
                command.Parameters.Add(new SqlParameter("@IsPublic", filter));
                connection.Open();
                List<Photo> list = new List<Photo>();
                using (SqlDataReader reader = command.ExecuteReader()) {
                    while (reader.Read()) {
                        Photo temp = new Photo(
                            (int)reader["PhotoID"],
                            (int)reader["AlbumID"],
                            (string)reader["Caption"]);
                        list.Add(temp);
                    }
                }
                return list;
            }
        }


    }

 

    // Helper 函数

    private static byte[] ResizeImageFile(byte[] imageFile, int targetSize) {
        using (System.Drawing.Image oldImage = System.Drawing.Image.FromStream(new MemoryStream(imageFile))) {
            Size newSize = CalculateDimensions(oldImage.Size, targetSize);
            using (Bitmap newImage = new Bitmap(newSize.Width, newSize.Height, PixelFormat.Format24bppRgb)) {
                using (Graphics canvas = Graphics.FromImage(newImage)) {
                    canvas.SmoothingMode = SmoothingMode.AntiAlias;
                    canvas.InterpolationMode = InterpolationMode.HighQualityBicubic;
                    canvas.PixelOffsetMode = PixelOffsetMode.HighQuality;
                    canvas.DrawImage(oldImage, new Rectangle(new Point(0, 0), newSize));
                    MemoryStream m = new MemoryStream();
                    newImage.Save(m, ImageFormat.Jpeg);
                    return m.GetBuffer();
                }
            }
        }
    }

    private static Size CalculateDimensions(Size oldSize, int targetSize) {
        Size newSize = new Size();
        if (oldSize.Height > oldSize.Width) {
            newSize.Width = (int)(oldSize.Width * ((float)targetSize / (float)oldSize.Height));
            newSize.Height = targetSize;
        } else {
            newSize.Width = targetSize;
            newSize.Height = (int)(oldSize.Height * ((float)targetSize / (float)oldSize.Width));
        }
        return newSize;
    }

    public static ICollection ListUploadDirectory() {
        DirectoryInfo d = new DirectoryInfo(System.Web.HttpContext.Current.Server.MapPath("~/Upload"));
        return d.GetFileSystemInfos("*.jpg");
    }

}

5.批量上传操作

    protected void Button1_Click(object sender, ImageClickEventArgs e) {
        DirectoryInfo d = new DirectoryInfo(Server.MapPath("~/Upload"));
        foreach (FileInfo f in d.GetFiles("*.jpg")) {
            byte[] buffer = new byte[f.OpenRead().Length];
            f.OpenRead().Read(buffer, 0, (int)f.OpenRead().Length);
            PhotoManager.AddPhoto(Convert.ToInt32(Request.QueryString["AlbumID"]), f.Name, buffer);
        }
        GridView1.DataBind();
    }

 6.上传控件
.net2.0 专门有一个上传服务器控件

<asp:FileUpload ID="PhotoFile" Runat="server" Width="416" FileBytes='<%# Bind("BytesOriginal") %>' CssClass="textfield" /><br />