ConvertImage(FileUpload1.PostedFile.FileName, 

System.Drawing.Imaging.ImageFormat.Gif, serverpath+".gif");
        }
        else if(DropDownList1.SelectedValue == "Jpeg")
        {
 

 

 

 

 

 

 

 

 

 

 

 

ConvertImage(FileUpload1.PostedFile.FileName, 

System.Drawing.Imaging.ImageFormat.Jpeg, serverpath + ".jpg");
        }
        else if(DropDownList1.SelectedValue == "Bmp")
        {
 

 

 

 

 

 

 

 

 

 

 

 

ConvertImage(FileUpload1.PostedFile.FileName, 

System.Drawing.Imaging.ImageFormat.Bmp, serverpath + ".bmp");
        }
        else
        {
        //清清月儿留给大家 http://blog.csdn.net/21aspnet
        }
    }

        public   void   ConvertImage(string   Filename,   System.Drawing.Imaging.ImageFormat 
DesiredFormat, string NewFilename)
    {
        try
        {
            System.Drawing.Image imgFile = System.Drawing.Image.FromFile(Filename);
            imgFile.Save(NewFilename, DesiredFormat);
            Image1.ImageUrl = NewFilename; 
            Label1.Text = "转换成功，生成"+NewFilename+"，如下所示。";
            TextBox1.Text = "1";//开始为 0，转换后为 1
        }
        catch (Exception ex)
        {
            Response.Write(ex);
        }
    }

}

 

前台代码：
<%@   Page   Language="C#"   AutoEventWireup="true"   CodeFile="Default.aspx.cs"