Determine if current page is using SSL in Rails

I'm trying to detect if the current page is being delivered via SSL in order to decide whethe开发者_运维技巧r or not to include certain unsecure external resources. My current method involves checking if request.url starts with 'https'. Is this the simplest way of accomplishing this? Is there a better way? Thanks!

---

In a controller or view:

request.ssl?