如何将文件从Web下载到ASP.NET Web应用程序中？

Question

I'm trying to download a file I recieve on the web into my ASP.NET web application, inside a seperate folder. Is it possible to do this? I tried using a WebClient to download the file but got an exception for InvalidOperationException.

InvalidOperationException was unhandled by user code

Asynchronous operations are not allowed in this context. Page starting an asynchronous operation has to have the Async attribute set to true and an asynchronous operation can only be started on a page prior to PreRenderComplete event.

And here's the code that causes the exception:

WebClient wc = new WebClient();
wc.DownloadFileCompleted += new System.ComponentModel.AsyncCompletedEventHandler(wc_DownloadFileCompleted);
wc.DownloadFileAsync(new Uri("research.microsoft.com/pubs/70177/tr-2005-68.pdf", UriKind.RelativeOrAbsolute), Server.MapPath("FileUploads/download.pdf"));

Answer 1

The following MSDN Article Asynchronous Pages in ASP.NET 2.0 does a nice job of explaining how you can handle async operations on a web page. The sample code in fact uses a WebRequest to download from http://msdn.microsoft.com