在ASP.NET中上传图片并生成缩略图

在ASP.NET中上传图片并生成缩略图，可以参照下列代码：

private void btnUploadPicture_Click(object sender, System.EventArgs e) 

{ 

//检查上传文件的格式是否有效 

if(this.UploadFile.PostedFile.ContentType.ToLower().IndexOf("image") < 0) 

{ 

Response.Write("上传图片格式无效！"); 

return; 

} 
//生成原图 

Byte[] oFileByte = new byte[this.UploadFile.PostedFile.ContentLength]; 

System.IO.Stream oStream = this.UploadFile.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 

int tWidth = 100; //设置缩略图初始宽度 

int tHeight = 100; //设置缩略图初始高度 
//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(oWidth))); 

} 

else 

{ 

tWidth = (int)Math.Floor(Convert.ToDouble(oWidth) * (Convert.ToDouble(tHeight) 
/ Convert.ToDouble(oHeight))); 

} 
//生成缩略原图 

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 oFullName = Server.MapPath(".") + "/" + "o" + 
DateTime.Now.ToShortDateString().Replace("-","") + DateTime.Now.Hour.ToString() 
+ DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString() 
+ DateTime.Now.Millisecond.ToString() + ".jpg"; //保存原图的物理路径 

string tFullName = Server.MapPath(".") + "/" + "t" + 
DateTime.Now.ToShortDateString().Replace("-","") + DateTime.Now.Hour.ToString() 
+ DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString() 
+ DateTime.Now.Millisecond.ToString() + ".jpg"; //保存缩略图的物理路径 
try 

{ 

//以JPG格式保存图片 

oImage.Save(oFullName,System.Drawing.Imaging.ImageFormat.Jpeg); 

tImage.Save(tFullName,System.Drawing.Imaging.ImageFormat.Jpeg); 

} 

catch(Exception ex) 

{ 

throw ex; 

} 

finally 

{ 

//释放资源 

oImage.Dispose(); 

g.Dispose(); 

tImage.Dispose(); 

} 

}