C#实现的上传图片、保存图片、加水印、生成缩略图功能示例

<form method="POST" enctype="multipart/form-data" action="UploadImg.ashx">  <table>    <tr>      <td>func：</td>      <td><input type="text" name="func"/></td>    </tr>    <tr>      <td>用户Id：</td>      <td><input type="text" name="userId"/></td>    </tr>    <tr>      <td>头像：</td>      <td><input type="file" name="icon"/></td>    </tr>    <tr>      <td>水印：</td>      <td><input type="text" name="waterMark"/></td>    </tr>  </table>  <input type="submit" value="提交"/></form>

private string UploadImage(HttpContext context){  try  {    System.IO.Stream stream = context.Request.Files["icon"].InputStream;    //返回的图片路径可以存储在数据库中    string imageUrl = SaveImage(stream, "Icon", "蝈蝈");    string thumbnailImageUrl = SaveThumbnailImage(stream, "Icon");    string thumbnailImageUrlWithWatermark = SaveThumbnailImage(ConfigurationManager.AppSettings["AttachmentsDirectory"] + imageUrl, "Icon");    return "上传成功！";  }  catch (Exception ex)  {    return "上传失败！";  }}private string SaveImage(Stream stream, string folderName, string waterMark){  try  {    string fileName = Guid.NewGuid() + ".jpg";    string path = ConfigurationManager.AppSettings["AttachmentsDirectory"];    path = Path.Combine(path, folderName + "//" + DateTime.Now.Year + "//" + DateTime.Now.Month + "//" + DateTime.Now.Day + "//");    string imageUrl = "/" + folderName + "/" + DateTime.Now.Year + "/" + DateTime.Now.Month + "/" + DateTime.Now.Day + "/";    if (!string.IsNullOrEmpty(waterMark))    {      Image imgSource = Image.FromStream(stream);      AddWatermarkAndSave(path, fileName, waterMark, imgSource, imgSource.Height - 300, 10, Color.Red,        new Font("宋体", 40));    }    else    {      byte[] buffer = new byte[stream.Length];      stream.Read(buffer, 0, buffer.Length);      if (!Directory.Exists(path))      {        Directory.CreateDirectory(path);      }      System.IO.FileStream fs = new System.IO.FileStream(path + fileName, System.IO.FileMode.OpenOrCreate,        System.IO.FileAccess.Write);      fs.Write(buffer, 0, buffer.Length);      fs.Flush();      fs.Close();    }    return imageUrl + fileName;  }  catch (Exception ex)  {    return "";  }}private string SaveThumbnailImage(Stream stream, string folderName){  try  {    string fileName = Guid.NewGuid() + ".jpg";    string path = ConfigurationManager.AppSettings["AttachmentsDirectory"];    path = Path.Combine(path, folderName + "//" + DateTime.Now.Year + "//" + DateTime.Now.Month + "//" + DateTime.Now.Day + "//");    string imageUrl = "/" + folderName + "/" + DateTime.Now.Year + "/" + DateTime.Now.Month + "/" + DateTime.Now.Day + "/";    System.Drawing.Image.GetThumbnailImageAbort myCallback = new System.Drawing.Image.GetThumbnailImageAbort(GetFalse);    //数据源来自Stream    Image image = System.Drawing.Bitmap.FromStream(stream);    System.Drawing.Image thumbnailImage = image.GetThumbnailImage(64, 64, myCallback, IntPtr.Zero);    thumbnailImage.Save(path + fileName);    thumbnailImage.Dispose();    return imageUrl + fileName;  }  catch (Exception ex)  {    return "";  }}private string SaveThumbnailImage(string originalFileName, string folderName){  try  {    string fileName = Guid.NewGuid() + ".jpg";    string path = ConfigurationManager.AppSettings["AttachmentsDirectory"];    path = Path.Combine(path, folderName + "//" + DateTime.Now.Year + "//" + DateTime.Now.Month + "//" + DateTime.Now.Day + "//");    string imageUrl = "/" + folderName + "/" + DateTime.Now.Year + "/" + DateTime.Now.Month + "/" + DateTime.Now.Day + "/";    System.Drawing.Image.GetThumbnailImageAbort myCallback = new System.Drawing.Image.GetThumbnailImageAbort(GetFalse);    //数据源来自File    Image image = System.Drawing.Bitmap.FromFile(originalFileName);    System.Drawing.Image thumbnailImage = image.GetThumbnailImage(64, 64, myCallback, IntPtr.Zero);    thumbnailImage.Save(path + fileName);    thumbnailImage.Dispose();    return imageUrl + fileName;  }  catch (Exception ex)  {    return "";  }}private bool GetFalse(){  return false;}/// <summary>/// 图片加文字水印/// </summary>/// <param name="fileName"> </param>/// <param name="text">水印文字，如果是多行用分号隔开</param>/// <param name="img">图片</param>/// <param name="paddingTop">上边距</param>/// <param name="paddingLeft">左边距</param>/// <param name="textColor">文字颜色</param>/// <param name="textFont">字体</param>/// <param name="path">保存地址</param>/// <returns></returns>private bool AddWatermarkAndSave(string path, string fileName, string text, Image img,      int paddingTop, int paddingLeft, Color textColor, Font textFont){  text = text + ";" + "当前时间：" + DateTime.Now.ToString("yyyy-MM-dd HH:mm");  if (!Directory.Exists(path))  {    Directory.CreateDirectory(path);  }  textFont = new Font("宋体", 19);  Bitmap bm = new Bitmap(img);  System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bm);  System.Drawing.Brush b = new SolidBrush(textColor);  string[] str = text.Split(';');  for (int i = 0; i < str.Length; i++)    g.DrawString(str[i], textFont, b, paddingLeft, paddingTop + 33 * i);  g.Dispose();  bm.Save(path + fileName, ImageFormat.Jpeg);  bm.Dispose();  return true;}