问题:

I am using Inno Setup to distribute my application. Is it possible to check in Inno Script for a particular condition and download and install some file from internet if required.

回答1:

Yes, there is a library called InnoTools Downloader which has samples that do pretty much this. They can be conditioned on anything you want using normal Inno code.

回答2:

Inno Download Plugin by Mitrich Software.

It's an InnoSetup script and DLL, which allows you to download files as part of your installation.
It supports FTP, HTTP and HTTPS.
It's kind of a drop-in replacement for InnoTools Downloader. Only few changes required.
It brings a decent download display and HTTPS and Mirror(s) support.

回答3:

Found on Inno 3rd Party is one very similar in scope and style to the Inno Download Plugin, DWinsHs.
Included with an easy and intuitive chm file which requires unblocking to view.