上传图片并生成缩略图

（1）

using System.IO; //添加

（2）

在页面上放入一个FileUpload控件，id为“FileUpload1”，和一个“上传”按钮，id为“btnUpload”。

/// <summary> 
///"上传"按钮 
/// </summary> 
/// <param name="sender"></param> 
/// <param name="e"></param> 
protected voidbtnUpload_Click(objectsender, EventArgse) 
{ 
    stringserverPath = Server.MapPath("~/images/product");//设置图片路径 

    if(this.FileUpload1.HasFile) 
    { 
        stringname=FileUpload1.FileName; 
        stringfName = this.txtImageName.Text; 
        if(string.IsNullOrEmpty(fName)) 
        { 
            fName = name; 
        } 
        stringtype = fName.Substring(fName.LastIndexOf(".") + 1).ToLower();            
        if(type == "jpg"|| type == "png"|| type == "bmp"|| type == "gif"|| type == "jpeg") 
        { 
            UpLoadImage(serverPath,fName);//执行上传图片，并生成缩略图 
        } 
        else 
       { 
            HttpContext.Current.Response.Write("<script>alert('图片格式不对!');</script>"); 
            return; 
        } 
    } 
    else 
   { 
        HttpContext.Current.Response.Write(" <script>alert('请选择要上传的文件') </script>"); 
        return; 
    } 
    HttpContext.Current.Response.Write(" <script>alert('文件上传成功') </script>"); 
} 

/// <summary> 
///执行上传图片操作，并生成缩略图 
/// </summary> 
/// <param name="serverPath"></param> 
/// <param name="fName"></param> 
private voidUpLoadImage(stringserverPath, stringfName) 
{ 
    if(!File.Exists(serverPath)) 
    { 
         Directory.CreateDirectory(serverPath); 
         Directory.CreateDirectory(serverPath + "_thumb"); 
    } 
    stringfPath = serverPath + "\\"+ fName;//文件实际路径

    Stringtpath = serverPath + "_thumb\\"+ fName;//缩略图路径 

    if(!File.Exists(tpath) && !File.Exists(fPath)) 
    {        
         this.FileUpload1.SaveAs(fPath);//上传到图片路径        
         ImageClass.MakeThumbnail(fPath, tpath, 180, 117, "w"); //调用ImageClass类的MakeThumbnail()方法，生成缩略图 
         this.myImage.ImageUrl = "~/images/product_thumb"+ "\\"+ fName; 
    } 
    else 
   { 
         HttpContext.Current.Response.Write("<script>alert('图片已存在!');</script>"); 
         return; 
    } 
}

（3）ImageClass类（转，网址忘记了）

//add 
usingSystem.Data; 
usingSystem.Configuration; 
usingSystem.Web.UI; 
usingSystem.IO;

/// <summary> 
///生成缩略图 
/// </summary> 
/// <param name="originalImagePath">源图路径（物理路径）</param> 
/// <param name="thumbnailPath">缩略图路径（物理路径）</param> 
/// <param name="width">缩略图宽度</param> 
/// <param name="height">缩略图高度</param> 
/// <param name="mode">生成缩略图的方式</param>  
public static voidMakeThumbnail(stringoriginalImagePath, stringthumbnailPath, intwidth, intheight, stringmode) 
{ 
    System.Drawing.ImageoriginalImage = System.Drawing.Image.FromFile(originalImagePath); 

    inttowidth = width; 
    inttoheight = height; 

    intx = 0; 
    inty = 0; 
    intow = originalImage.Width; 
    intoh = originalImage.Height; 

    if(ow < towidth && oh < toheight) 
    { 
        originalImage.Save(thumbnailPath); 
    } 
    else 
   { 

        switch(mode.ToUpper()) 
        { 
            case"HW"://指定高宽缩放（可能变形）          
                break; 
            case"W"://指定宽，高按比例            
                toheight = originalImage.Height * width / originalImage.Width; 
                break; 
            case"H"://指定高，宽按比例 
                towidth = originalImage.Width * height / originalImage.Height; 
                break; 
            case"CUT"://指定高宽裁减（不变形）          
                if((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight) 
                { 
                    oh = originalImage.Height; 
                    ow = originalImage.Height * towidth / toheight; 
                    y = 0; 
                    x = (originalImage.Width - ow) / 2; 
                } 
                else 
               { 
                    ow = originalImage.Width; 
                    oh = originalImage.Width * height / towidth; 
                    x = 0; 
                    y = (originalImage.Height - oh) / 2; 
                } 
                break; 
            case"AUTO": //自动适应高度 
                if(ow > oh) 
                { 
                    //newwidth = 200; 
                   toheight = (int)((double)oh / (double)ow * (double)towidth); 
                } 
                else 
               { 
                    //newheight = 200; 
                   towidth = (int)((double)ow / (double)oh * (double)toheight); 
                } 
                break; 
            default: 
                break; 
        } 

        //新建一个bmp图片 
        System.Drawing.Imagebitmap = newSystem.Drawing.Bitmap(towidth, toheight); 

        //新建一个画板 
        System.Drawing.Graphicsg = System.Drawing.Graphics.FromImage(bitmap); 

        //设置高质量插值法 
        g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; 

        //设置高质量,低速度呈现平滑程度 
        g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; 

        //清空画布并以透明背景色填充 
        g.Clear(System.Drawing.Color.Transparent); 

        //在指定位置并且按指定大小绘制原图片的指定部分 
        g.DrawImage(originalImage, newSystem.Drawing.Rectangle(0, 0, towidth, toheight), 
            newSystem.Drawing.Rectangle(x, y, ow, oh), 
            System.Drawing.GraphicsUnit.Pixel); 

        try 
       { 
            //以jpg格式保存缩略图 
            bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg); 

        } 
        catch(System.Exceptione) 
        { 
            throwe; 
        } 
        finally 
       { 

            bitmap.Dispose(); 
            g.Dispose(); 
        } 
    } 
    originalImage.Dispose(); 
}