在线图片服务设计小计

（1）图片处理类库 http://imageresizing.net/docs
（2）asp.net mvc 输出请求图片加缓存
https://github.com/terjetyl/Simple.ImageResizer https://github.com/terjetyl/Simple.ImageResizer/tree/master/samples/Simple.ImageResizer.MvcDemo https://github.com/terjetyl/Simple.ImageResizer/blob/master/samples/Simple.ImageResizer.MvcDemo/Controllers/ImagesController.cs https://github.com/keyvan/ImageResizer4DotNet/tree/master/ImageResizer4DotNet/ImageResizer4DotNet
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public FileStreamResult Download()
	{
	var fullQualifiedPathToDll = Path.Combine(Server.MapPath("~/"), "bin/Simple.ImageResizer.dll");
	var fileInfo = new FileInfo(fullQualifiedPathToDll);
	var myFileStream = new FileStream(fullQualifiedPathToDll, FileMode.Open);
	return File(myFileStream, "application/octet-stream", fileInfo.Name);
	}