C#实现的上传图片、保存图片、加水印、生成缩略图功能示例

本文实例讲述了C#实现的上传图片、保存图片、加水印、生成缩略图功能。分享给大家供大家参考，具体如下：

伴随移动设备地普及，处理图片、视频等需求也变得越来越基础，这里介绍的是图片的存储。

上传图片必须使用form表单提交的方式，我只知道这一种方法，如果大家知道其他方法的话请留言。

保存图片、加水印和生成缩略图这三种功能最好各自放在单独的方法中，尽量降低耦合度，提高代码复用程度，除此之外我们平常写代码是也要尽量做到方 * 能的唯一性。

前台代码：

<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>

后台代码：

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;
}

希望本文所述对大家C#程序设计有所帮助。

来源：https://blog.csdn.net/xiaouncle/article/details/54883327