在ASP.NET中上传图片并生成缩略图

在ASP.NET中上传图片并生成缩略图，可以参照下列代码：

private void btnUploadPicture_Click(object sender, System.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(".") + "/" + "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(".") + "/" + "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(); } }

 

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