C# 上传文件并生成缩略图

#region 上传文件并生成缩略图
/// <summary>
/// 上传文件并生成缩略图
/// </summary>
/// <param name="paramFileUpload">上传控件</param>
/// <param name="paramVirtualPath">上传目标虚拟路径</param>
/// <param name="paramDirectory">用户自定义创建文件夹</param>
/// <param name="paramOriginalDirectory">存放原始文件夹</param>
/// <param name="paramThumbnailDirectory">存放缩略图文件夹</param>
/// <param name="tWidth">缩略图默认宽度</param>
/// <param name="tHeight">缩略图默认高度</param>
private string UploadAndThumbnail(FileUpload paramFileUpload, string paramVirtualPath, string paramDirectory, string paramOriginalDirectory, string paramThumbnailDirectory, int tWidth, int tHeight, string paramFileName)
{
string returnValue = string.Empty;//返回值
string imgType;//文件类型
string fullFileName = paramFileUpload.PostedFile.FileName; //上传文件名
imgType = fullFileName.Substring(fullFileName.LastIndexOf(".") + 1).ToLower();//文件类型
string UserPath = Server.MapPath(paramVirtualPath).ToString() + "\\" + paramDirectory;//存放文件目录
//如果文件夹不存在则创建
if (!Directory.Exists(UserPath))
{
Directory.CreateDirectory(UserPath);
}
string originalImagePath = UserPath + "\\" + paramOriginalDirectory;//原始路径
if (!Directory.Exists(originalImagePath))
{
Directory.CreateDirectory(originalImagePath);
}
string thumbnailPath = UserPath + "\\" + paramThumbnailDirectory;
if (!Directory.Exists(thumbnailPath))
{
Directory.CreateDirectory(thumbnailPath);
}
// 获取上传图像的文件名
string fileName = paramFileName;

if (imgType == "jpg" || imgType == "jpeg" || imgType == "bmp" || imgType == "png" || imgType == "icon")
{
try
{
//生成原图
byte[] oFileByte = new byte[paramFileUpload.PostedFile.ContentLength];
Stream oStream = paramFileUpload.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
if (tWidth == 0)
{
tWidth = 100;
}
if (tHeight == 0)
{
tHeight = 100;
}
//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(oHeight)));
}
else
{
tWidth = (int)Math.Floor(Convert.ToDouble(oWidth) * (Convert.ToDouble(tHeight) / Convert.ToDouble(oHeight)));
}
//生成缩略图
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 oPath = originalImagePath + "\\" + fileName + ".jpg";
string tPath = thumbnailPath + "\\" + fileName + ".jpg";
//以JPG格式保存图像
oImage.Save(oPath, System.Drawing.Imaging.ImageFormat.Jpeg);
tImage.Save(tPath, System.Drawing.Imaging.ImageFormat.Jpeg);
returnValue = "上传成功！";
//释放资源
oImage.Dispose();
g.Dispose();
tImage.Dispose();
}
catch (Exception ex)
{
returnValue = "由于网络原因，上载文件错误 " + ex.Message;
}
}
else
{
returnValue = "你选择的图像格式错误!";
}
return returnValue;
}
#endregion