asp.net上传图片并同时生成缩略图C#代码

using System;  using System.Data;  using System.Configuration;  using System.Collections;  using System.Web;  using System.Web.Security;  using System.Web.UI;  using System.Web.UI.WebControls;  using System.Web.UI.WebControls.WebParts;  using System.Web.UI.HtmlControls;  using System.Drawing;  public partial class slt_Default : System.Web.UI.Page  {      protected void Page_Load(object sender, EventArgs e)      {      }      protected void bt_upload_Click(object sender, EventArgs e)      {          //检查上传文件的格式是否有效           if (this.UploadFile.PostedFile.ContentType.ToLower().IndexOf("image") < 0)          {              Response.Write("上传图片格式无效！");              return;          }          //生成原图           Byte[] oFileByte = new byte[this.UploadFile.PostedFile.ContentLength];          System.IO.Stream oStream = this.UploadFile.PostedFile.InputStream;          System.Drawing.Image oImage = System.Drawing.Image.FromStream(oStream);          int oWidth = oImage.Width; //原图宽度           int oHeight = oImage.Height; //原图高度           int tWidth = 100; //设置缩略图初始宽度           int tHeight = 100; //设置缩略图初始高度          //按比例计算出缩略图的宽度和高度           if (oWidth >= oHeight)          {              tHeight = (int)Math.Floor(Convert.ToDouble(oHeight) * (Convert.ToDouble(tWidth) / Convert.ToDouble(oWidth)));          }          else          {              tWidth = (int)Math.Floor(Convert.ToDouble(oWidth) * (Convert.ToDouble(tHeight) / Convert.ToDouble(oHeight)));          }          //生成缩略原图           Bitmap tImage = new Bitmap(tWidth, tHeight);          Graphics g = Graphics.FromImage(tImage);          g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; //设置高质量插值法           g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;//设置高质量,低速度呈现平滑程度           g.Clear(Color.Transparent); //清空画布并以透明背景色填充           g.DrawImage(oImage, new Rectangle(0, 0, tWidth, tHeight), new Rectangle(0, 0, oWidth, oHeight), GraphicsUnit.Pixel);          string oFullName = Server.MapPath(".") + "/image/" + "o" + DateTime.Now.ToShortDateString().Replace("-", "") + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString() + DateTime.Now.Millisecond.ToString() + ".jpg"; //保存原图的物理路径           string tFullName = Server.MapPath(".") + "/image/" + "t" + DateTime.Now.ToShortDateString().Replace("-", "") + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString() + DateTime.Now.Millisecond.ToString() + ".jpg"; //保存缩略图的物理路径          try          {              //以JPG格式保存图片               oImage.Save(oFullName, System.Drawing.Imaging.ImageFormat.Jpeg);              tImage.Save(tFullName, System.Drawing.Imaging.ImageFormat.Jpeg);          }          catch (Exception ex)          {              throw ex;          }          finally          {              //释放资源               oImage.Dispose();              g.Dispose();              tImage.Dispose();          }      }    }