ASP.NET中上传图片并生成缩略图

HTML:

  <asp:Label ID="lblPicInfo" runat="server"></asp:Label>&nbsp;

        <asp:Button ID="Button1" runat="server" Text="原始图片" />
        <asp:FileUpload ID="FileUpload1" runat="server" />
        <asp:Button ID="Button2" runat="server" OnClick="UploadFile" Text="保存缩略图" /></div>

 

CS代码:

 

using System;
using System.Collections; 
using System.ComponentModel; 
using System.Data; 
using System.Drawing; 
using System.Web; 
using System.Web.SessionState; 
using System.Web.UI; 
using System.Web.UI.WebControls; 
using System.Web.UI.HtmlControls; 
using System.IO; 
using System.Drawing.Imaging;
using System.Text;  

    /**//// <summary> 
    /// Thumbnail 的摘要说明。 
    /// </summary> 
    public partial class Thumbnail : System.Web.UI.Page
    {
      

        private void Page_Load(object sender, System.EventArgs e)
        {
            // 在此处放置用户代码以初始化页面 
          
            Button1.Text = "上载并显示缩略图";

        }

        Web 窗体设计器生成的代码#region Web 窗体设计器生成的代码
        override protected void OnInit(EventArgs e)
        {
            // 
            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。 
            // 
            InitializeComponent();
            base.OnInit(e);
        }

        /**//// <summary> 
        /// 设计器支持所需的方法 - 不要使用代码编辑器修改 
        /// 此方法的内容。 
        /// </summary> 
        private void InitializeComponent()
        {
            this.Button1.Click += new System.EventHandler(this.Button1_Click);
            this.Load += new System.EventHandler(this.Page_Load);

        }
        #endregion

        private void Button1_Click(object sender, System.EventArgs e)
        {
            HttpFileCollection MyFileColl = HttpContext.Current.Request.Files;
            HttpPostedFile MyPostedFile = MyFileColl[0];

            if (MyPostedFile.ContentType.ToString().ToLower().IndexOf("image") < 0)
            {
                Response.Write("无效的图形格式。");
                return;
            }
         
            GetThumbNail(MyPostedFile.FileName, 100, 100,
            MyPostedFile.ContentType.ToString(), false, MyPostedFile.InputStream);
        }
        private System.Drawing.Imaging.ImageFormat GetImageType(object strContentType)
        {
            if ((strContentType.ToString().ToLower()) == "image/pjpeg")
            {
                return System.Drawing.Imaging.ImageFormat.Jpeg;
            }
            else if ((strContentType.ToString().ToLower()) == "image/gif")
            {
                return System.Drawing.Imaging.ImageFormat.Gif;
            }
            else if ((strContentType.ToString().ToLower()) == "image/bmp")
            {
                return System.Drawing.Imaging.ImageFormat.Bmp;
            }
            else if ((strContentType.ToString().ToLower()) == "image/tiff")
            {
                return System.Drawing.Imaging.ImageFormat.Tiff;
            }
            else if ((strContentType.ToString().ToLower()) == "image/x-icon")
            {
                return System.Drawing.Imaging.ImageFormat.Icon;
            }
            else if ((strContentType.ToString().ToLower()) == "image/x-png")
            {
                return System.Drawing.Imaging.ImageFormat.Png;
            }
            else if ((strContentType.ToString().ToLower()) == "image/x-emf")
            {
                return System.Drawing.Imaging.ImageFormat.Emf;
            }
            else if ((strContentType.ToString().ToLower()) == "image/x-exif")
            {
                return System.Drawing.Imaging.ImageFormat.Exif;
            }
            else if ((strContentType.ToString().ToLower()) == "image/x-wmf")
            {
                return System.Drawing.Imaging.ImageFormat.Wmf;
            }
            else
            {
                return System.Drawing.Imaging.ImageFormat.MemoryBmp;
            }
        }

        private void GetThumbNail(string strFileName, int iWidth, int iheight,
        string strContentType, bool blnGetFromFile, System.IO.Stream ImgStream)
        {
            System.Drawing.Image oImg;

            if (blnGetFromFile)
            {
                oImg = System.Drawing.Image.FromFile(strFileName);
            }
                 
            else
            {
                oImg = System.Drawing.Image.FromStream(ImgStream);
            }
            //oImg = oImg.GetThumbnailImage(iWidth, iheight, null, IntPtr.Zero);
            oImg = oImg.GetThumbnailImage(oImg.Size.Width, oImg.Size.Height, null, IntPtr.Zero);
            string strGuid = System.Guid.NewGuid().ToString().ToUpper();
            string strFileExt = strFileName.Substring(strFileName.LastIndexOf("."));
            Response.ContentType = strContentType;
            MemoryStream MemStream = new MemoryStream();
            oImg.Save(MemStream, GetImageType(strContentType));
            MemStream.WriteTo(Response.OutputStream);
        }



        public void UploadFile(object sender, System.EventArgs e)
        {
            HttpFileCollection MyFileColl = HttpContext.Current.Request.Files;
            HttpPostedFile MyPostedFile = MyFileColl[0];
            if (MyPostedFile.ContentType.ToString().ToLower().IndexOf("image") < 0)
            {
                Response.Write("无效的图形格式。");
                return;
            }
            string imgNameOnly, imgNameNoExt, imgExt;
            string imgThumbnail;
            int erroNumber = 0;
            System.Drawing.Image oriImg, newImg;
            string strFePicSavePath = Server.MapPath("SmallPic")+"\\";
            string strFePicThumbFormat = ".jpg";
            int intFeThumbWidth = 30;
           // string strFePicSavePath = ConfigurationSettings.AppSettings["FePicSavePath"].ToString();
           // string strFePicThumbFormat = ConfigurationSettings.AppSettings["FePicThumbFormat"].ToString().ToLower();
            //int intFeThumbWidth = Int32.Parse(ConfigurationSettings.AppSettings["FePicThumbWidth"]);
            string fileExt;

            StringBuilder picInfo = new StringBuilder();

            if (Page.IsValid)
            {


                for (int i = 0; i < Request.Files.Count; i++)
                {
                    HttpPostedFile PostedFile = Request.Files[i];
                    fileExt = (System.IO.Path.GetExtension(PostedFile.FileName)).ToString().ToLower();

                    imgNameOnly = System.IO.Path.GetFileName(PostedFile.FileName);
                    if (fileExt != ".jpg" && fileExt != ".gif" && fileExt == ".png")
                    {
                        erroNumber = erroNumber + 1;
                        picInfo.Append("<b>错误：</b>文件(" + (i + 1) + ") " + imgNameOnly + " 扩展名 " + fileExt + " 不被许可<br/>");

                       
                    }
                   

                }

                if (erroNumber > 0)
                {
                    picInfo.Append("<font color=red>全部操作均未完成，请修改错误，再进行操作</font><br/>");
                }
                else
                {
                    for (int i = 0; i < Request.Files.Count; i++)
                    {

                        HttpPostedFile PostedFile = Request.Files[i];
                        imgNameOnly = System.IO.Path.GetFileName(PostedFile.FileName);
                        imgNameNoExt = System.IO.Path.GetFileNameWithoutExtension(PostedFile.FileName);
                        imgExt = System.IO.Path.GetExtension(PostedFile.FileName).ToString().ToLower();


                        oriImg = System.Drawing.Image.FromStream(PostedFile.InputStream);
                        newImg = oriImg.GetThumbnailImage(intFeThumbWidth, intFeThumbWidth * oriImg.Height / oriImg.Width, null, new System.IntPtr(0));
                        switch (imgExt)
                        {
                            //case ".jpeg": 
                            case ".jpg":
                                oriImg.Save(strFePicSavePath + imgNameOnly, System.Drawing.Imaging.ImageFormat.Jpeg);
                                break;
                            case ".gif":
                                oriImg.Save(strFePicSavePath + imgNameOnly, System.Drawing.Imaging.ImageFormat.Gif);
                                break;
                            case ".png":
                                oriImg.Save(strFePicSavePath + imgNameOnly, System.Drawing.Imaging.ImageFormat.Png);
                                break;
                        }

                        //oriImg.Save(ConfigurationSettings.AppSettings["FePicSavePath"] + imgNameNoExt + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg); 

                        switch (strFePicThumbFormat)
                        {
                            //jpeg format can get the smallest file size, and the png is the largest size 
                            //case "jpeg": 
                            case "jpg":
                                newImg.Save(strFePicSavePath + imgNameOnly + "_thumb.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
                                imgThumbnail = imgNameOnly + "_thumb.jpg";
                                break;
                            case "gif":
                                newImg.Save(strFePicSavePath + imgNameOnly + "_thumb.gif", System.Drawing.Imaging.ImageFormat.Gif);
                                imgThumbnail = imgNameOnly + "_thumb.gif";
                                break;
                            case "png":
                                newImg.Save(strFePicSavePath + imgNameOnly + "_thumb.png", System.Drawing.Imaging.ImageFormat.Png);
                                imgThumbnail = imgNameOnly + "_thumb.png";
                                break;
                            default:
                                newImg.Save(strFePicSavePath + imgNameOnly + "_thumb.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
                                imgThumbnail = imgNameOnly + "_thumb.jpg";
                                break;

                        }//switch 

                        picInfo.Append("<b>文件　名：</b>" + imgNameOnly + " ( " + oriImg.Width + " x " + oriImg.Height + " ) " + PostedFile.ContentLength / 1024 + "KB<br/>");
                        picInfo.Append("<b>缩略图名：</b>" + imgThumbnail + " ( " + newImg.Width + " x " + newImg.Height + " )<br/><br/>");

                        oriImg.Dispose();
                        newImg.Dispose();

                    }//for 
                    picInfo.Append("<font color=red>所有操作成功</font><br/>");

                }// if erronumber = 0 



            }
            else
            {
                picInfo.Append("<font color=red>有错误，请检查。操作未成功</font><br/>");

            }

            lblPicInfo.Text = picInfo.ToString();

        }
    }