How to upload files inside WebView?

Question

I have an application that loads WebView. Inside the WebView, the loaded page has a file upload control (html input = file). The button is visible and it says “Select File,” however, if you press the button, nothing will happen. If you use the default Android browser and load the same page and click on the button, it displays a window allowing you to select a file from your gallery, files, etc. Why doesn't it work from WebView?

I suppose I need to redefine something, but I don't know what it could be. Basically, I want to be able to download photos from my application, as I can already do from my web application that runs in a browser. The native version of the / webview application should work the same way, but the "Select File" button does nothing.

Thanks.