您现在的位置：程式碼之家 >> 編程語言 > >> .NET 網頁程式設計 >> ASP.NET 基礎 >> 關於ASP.NET

ASP.NET 檔案上傳管理策略：大小限制、類型驗證、縮圖生成、重新命名與資料庫記錄完整實作

編輯：關於ASP.NET

企業級檔案上傳需兼顧安全、效能、可維護性。本文提供完整上傳處理流程：驗證 → 重命名 → 存檔 → 縮圖 → 記錄 DB → 回應。

前端上傳頁面 (Upload.aspx)

<form id="form1" runat="server" enctype="multipart/form-data">
  <asp:FileUpload ID="FileUpload1" runat="server" />
  <asp:Button ID="ButtonUp" runat="server" Text="上傳" OnClick="ButtonUp_Click" />
  <asp:Label ID="LabelTitle2" runat="server" Text="*上傳檔案不能超過 2MB" ForeColor="Red" />
  <br />原始檔名：<span id="FileName" runat="server" />
  <br />儲存路徑：<span id="SaveDir" runat="server" />
  <br />縮圖路徑：<span id="sSaveDir" runat="server" />
  <br />檔案類型：<span id="FileType" runat="server" />
  <br />檔案大小：<span id="FileLength" runat="server" />
  <br />副檔名：<span id="FileExtention" runat="server" />
  <br />上傳時間：<span id="UpDateTime" runat="server" />
  <br /><asp:Image ID="Image1" runat="server" />
</form>

後端完整邏輯 (Upload.aspx.cs)

protected void ButtonUp_Click(object sender, EventArgs e)
{
    if (!FileUpload1.HasFile) { ShowAlert("請選擇檔案"); return; }

    // 1. 基本資訊
    string origName = FileUpload1.FileName;
    long fileSize = FileUpload1.PostedFile.ContentLength;
    string contentType = FileUpload1.PostedFile.ContentType;
    string ext = Path.GetExtension(origName).ToUpper();

    FileName.InnerHtml = origName;
    UpDateTime.InnerHtml = DateTime.Now.ToShortDateString();
    FileLength.InnerHtml = FormatFileSize(fileSize);
    FileType.InnerHtml = contentType;
    FileExtention.InnerHtml = ext;

    // 2. 大小限制 (2MB)
    if (fileSize > 2 * 1024 * 1024) { ShowAlert("檔案超過 2MB 限制"); return; }

    // 3. 類型驗證 (僅允許 JPG)
    if (ext != ".JPG" && ext != ".JPEG") { ShowAlert("僅允許 JPG 格式"); return; }

    // 4. 產生唯一檔名：域名-時間戳-副檔名
    string timestamp = DateTime.Now.ToString("yyyy-MM-dd-HH-mm-ss-ffff").Replace(".", "-");
    string saveName = $"www.MWO.Com-{timestamp}{ext}";
    string thumbName = $"www.MWO.Com-{timestamp}{ext}";

    string savePath = Server.MapPath("~/photo/") + saveName;
    string thumbPath = Server.MapPath("~/SPhoto/") + thumbName;

    SaveDir.InnerHtml = savePath;
    sSaveDir.InnerHtml = thumbPath;

    // 5. 生成高品質縮圖 (118x90)
    MakeHighQualityThumbnail(FileUpload1.PostedFile, thumbPath, 118, 90);

    // 6. 儲存原圖
    FileUpload1.SaveAs(savePath);

    // 7. 寫入資料庫
    PhotoInfo info = new PhotoInfo
    {
        Organization = "5173",
        PicName = origName,
        ServerName = "GLSDB",
        Cdate = DateTime.Now,
        Exp = ext,
        Flag = 0,
        GameNickName = "Bruce",
        MoonStar = 0,
        ShowIndex = 0,
        SPicHttpAddr = thumbPath,
        Type = 0,
        Vote = 0,
        PicHttpAddr = savePath
    };
    new PhotoDAO().Insert(info);

    ShowAlert("上傳成功");
    Image1.ImageUrl = "~/SPhoto/" + thumbName; // 即時預覽
}

// 高品質縮圖：保持比例、雙三次插值、平滑模式
public void MakeHighQualityThumbnail(HttpPostedFile postedFile, string savePath, double maxW, double maxH)
{
    using (Image src = Image.FromStream(postedFile.InputStream, true))
    {
        double ratio = Math.Min(maxW / src.Width, maxH / src.Height);
        int nW = (int)(src.Width * ratio);
        int nH = (int)(src.Height * ratio);

        using (Bitmap bmp = new Bitmap(nW, nH))
        using (Graphics g = Graphics.FromImage(bmp))
        {
            g.InterpolationMode = Drawing2D.InterpolationMode.HighQualityBicubic;
            g.SmoothingMode = Drawing2D.SmoothingMode.HighQuality;
            g.Clear(Color.White);
            g.DrawImage(src, new Rectangle(0, 0, nW, nH), new Rectangle(0, 0, src.Width, src.Height), GraphicsUnit.Pixel);
            bmp.Save(savePath, ImageFormat.Jpeg);
        }
    }
}

private string FormatFileSize(long bytes)
{
    if (bytes < 1024) return $"{bytes} Bytes";
    if (bytes < 1024 * 1024) return $"{bytes / 1024} KB";
    return $"{bytes / 1024 / 1024} MB";
}
private void ShowAlert(string msg) => Response.Write($"");