C#上传图片，同时生成缩略图

/// <summary>
/// uploadJaeyi 的摘要说明
/// </summary>
public class uploadJaeyi : IHttpHandler
{
ILog log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
public void ProcessRequest(HttpContext context)
{
string serverPath = context.Server.MapPath("/Upload/Jaeyi/");
if (!Directory.Exists(serverPath))
{
Directory.CreateDirectory(serverPath);
}
string serverSmallPath = context.Server.MapPath("/Upload/Jaeyi/Small/");
if (!Directory.Exists(serverSmallPath))
{
Directory.CreateDirectory(serverSmallPath);
}
HttpFileCollection files = context.Request.Files;
if (files.Count > 0)
{
for (int i = 0; i < files.Count; i++)
{
try
{
System.IO.Stream stream = files[i].InputStream;
string fileFullName = files[i].FileName;
int index = fileFullName.LastIndexOf("\\");
string fileName = fileFullName.Substring(index + 1);
//得到指定上传文件的字节输入流
int imgDataLen = (int)(stream.Length);
byte[] imgData = new byte[imgDataLen];
int n = stream.Read(imgData, 0, imgDataLen);
stream.Close();
FileStream fs = new FileStream(serverPath + fileName, FileMode.OpenOrCreate, FileAccess.Write);
fs.Write(imgData, 0, imgDataLen);
fs.Flush();
fs.Close();

string oldpath = serverPath + fileName;
string newpath = serverSmallPath + fileName;
MakeThumbnail(oldpath, newpath, 40, 40, "H");
}
catch (Exception ex)
{
log.Error("捷易拍照上传失败：" + ex);
}
}
}
}

/// <summary>
/// 生成缩略图
/// </summary>
/// <param name="originalImagePath">源图路径（物理路径）</param>
/// <param name="thumbnailPath">缩略图路径（物理路径）</param>
/// <param name="width">缩略图宽度</param>
/// <param name="height">缩略图高度</param>
/// <param name="mode">生成缩略图的方式</param>
public void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
{
System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);

int towidth = width;
int toheight = height;

int x = 0;
int y = 0;
int ow = originalImage.Width;
int oh = originalImage.Height;

switch (mode)
{
case "HW"://指定高宽缩放（可能变形）
break;
case "W"://指定宽，高按比例
toheight = originalImage.Height * width / originalImage.Width;
break;
case "H"://指定高，宽按比例
towidth = originalImage.Width * height / originalImage.Height;
break;
case "Cut"://指定高宽裁减（不变形）
if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
{
oh = originalImage.Height;
ow = originalImage.Height * towidth / toheight;
y = 0;
x = (originalImage.Width - ow) / 2;
}
else
{
ow = originalImage.Width;
oh = originalImage.Width * height / towidth;
x = 0;
y = (originalImage.Height - oh) / 2;
}
break;
default:
break;
}

//新建一个bmp图片
System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

//新建一个画板
Graphics g = System.Drawing.Graphics.FromImage(bitmap);

//设置高质量插值法
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

//设置高质量,低速度呈现平滑程度
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

//清空画布并以透明背景色填充
g.Clear(Color.Transparent);

//在指定位置并且按指定大小绘制原图片的指定部分
g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
new Rectangle(x, y, ow, oh),
GraphicsUnit.Pixel);
try
{
//以jpg格式保存缩略图
bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
bitmap.Dispose();
g.Dispose();
}
}

public bool IsReusable
{
get
{
return false;
}
}
}