环境：VS.NET2005 + Windows2003
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就是一个简单的将图片上传到服务器，并按照需求生成缩略图。在上传图片较大的时候，可以生成一个较小的图片放在网页里，这样可以加快浏览的速度。可根据需要链接到大图片再仔细浏览。
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不是很复杂，大概写一下。目的只在于实现，未仔细按照标准什么的来写。其中参考了网上已经存在的代码。
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using System.Drawing;
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页面，如图：
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点击提交按钮：
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HttpPostedFile hpf = UploadImage.PostedFile;
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//取得文件名(不含路径)
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char[] splitChar = { ‘\\\\’ };
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string[] FilenameArray = hpf.FileName.Split(splitChar);
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string Filename = FilenameArray[FilenameArray.Length - 1].ToLower();
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if (hpf.FileName.Length < 1)
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{
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Response.Write(“请选择您要上传的图片文件“);
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return;
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}
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if (hpf.ContentType != “image/pjpeg” && hpf.ContentType != “image/gif”)
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{
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Response.Write(“只允许上传 GIF JPG类型的文件“);
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return;
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}
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else
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{
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System.Text.StringBuilder sb = new System.Text.StringBuilder();
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sb.Append(DateTime.Now.Year.ToString());
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sb.Append(DateTime.Now.Month.ToString());
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sb.Append(DateTime.Now.Day.ToString());
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sb.Append(DateTime.Now.Hour.ToString());
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sb.Append(DateTime.Now.Minute.ToString());
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sb.Append(DateTime.Now.Second.ToString());
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if (Filename.ToLower().EndsWith(“gif”))
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{
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sb.Append(“.gif”);
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}
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else if (Filename.ToLower().EndsWith(“jpg”))
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{
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sb.Append(“.jpg”);
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}
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else if (Filename.ToLower().EndsWith(“jpeg”))
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{
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sb.Append(“.jpeg”);
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}
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Filename = sb.ToString();
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}
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// 保存图片到服务器上
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try
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{
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hpf.SaveAs(Server.MapPath(“..”) + “/Image/” + Filename);
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}
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catch (Exception ee)
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{
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Response.Write(“上传图片失败，原因” + ee.Message);
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return;
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}
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// 生成缩略图
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//原始图片名称
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string originalFilename = hpf.FileName;
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//生成的高质量图片名称
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string strFile = Server.MapPath(“..”) + “/Image/Small_” + Filename;
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//从文件取得图片对象
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System.Drawing.Image image = System.Drawing.Image.FromStream(hpf.InputStream, true);
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Double Width = Double.Parse(TextBox1.Text.Trim());
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Double Height = Double.Parse(TextBox2.Text.Trim());
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System.Double NewWidth, NewHeight;
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if (image.Width > image.Height)
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{
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NewWidth = Width;
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NewHeight = image.Height * (NewWidth / image.Width);
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}
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else
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{
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NewHeight = Height;
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NewWidth = (NewHeight / image.Height) * image.Width;
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}
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if (NewWidth > Width)
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{
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NewWidth = Width;
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}
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if (NewHeight > Height)
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{
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NewHeight = Height;
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}
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System.Drawing.Size size = new Size((int)NewWidth, (int)NewHeight); // 图片大小
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System.Drawing.Image bitmap = new System.Drawing.Bitmap(size.Width, size.Height); //新建bmp图片
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System.Drawing.Graphics graphics = System.Drawing.Graphics.FromImage(bitmap); //新建画板
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graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; //设置高质量插值法
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graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //设置高质量,低速度呈现平滑程度
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graphics.Clear(Color.White); //清空画布
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//在指定位置画图
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graphics.DrawImage(image, new System.Drawing.Rectangle(0, 0, bitmap.Width, bitmap.Height),
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new System.Drawing.Rectangle(0, 0, image.Width, image.Height),
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System.Drawing.GraphicsUnit.Pixel);
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//文字水印
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System.Drawing.Graphics textGraphics = System.Drawing.Graphics.FromImage(bitmap);
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System.Drawing.Font font = new Font(“宋体“, 10);
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System.Drawing.Brush brush = new SolidBrush(Color.Black);
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textGraphics.DrawString(TextBox3.Text.Trim(), font, brush, 10, 10);
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textGraphics.Dispose();
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///图片水印
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//System.Drawing.Image copyImage = System.Drawing.Image.FromFile(System.Web.HttpContext.Current.Server.MapPath(“pic/1.gif”));
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//Graphics a = Graphics.FromImage(bitmap);
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//a.DrawImage(copyImage, new Rectangle(bitmap.Width-copyImage.Width,bitmap.Height-copyImage.Height,copyImage.Width, copyImage.Height),0,0, copyImage.Width, copyImage.Height, GraphicsUnit.Pixel);
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//copyImage.Dispose();
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//a.Dispose();
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//copyImage.Dispose();
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//保存缩略图
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try
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{
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bitmap.Save(strFile, System.Drawing.Imaging.ImageFormat.Jpeg);
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}
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catch (Exception ex)
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{
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Response.Write(“保存缩略图失败:” + ex.Message);
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}
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graphics.Dispose();
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image.Dispose();
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bitmap.Dispose();
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整个实现的过程如下面的图：
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浏览页面，选择图片：
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点击提交后，图片以及缩略图都已经生成到了目标文件夹里面：
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可以看到，缩略图里面文字水印已经生成：
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至此，整个功能已实现。
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在生成缩略图的时候，可以根据需要对图片以及水印进行处理。更多帮助，请参阅MSDN。
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来源：http://blog.csdn.net/cqfeng
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