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How to get a file’s creation date or file size, for example this Hello.jpg at http://www.mywebsite.com/now/Hello.jpg(note: This URL does not exist)? The purpose of this question is to make my application re-download the files from the any website when it has detected that the website has an updated version of the files and the files in my local folder are out of date. Any ideas?
If you use the HEAD request it will send the headers for the resource, there you can check the cache control headers which will tell you if the resource has been modified, last modification time, size (content-length) and date.
Note that you’ll probably have to decorate this basic and easy approach with many heuristics depending on the craziness of each webserver’s admin, as each can send whatever headers they like. If they do not provide caching headers (Last-Modified, Expires, Cache-Control) nor Content-Length nor etag, you’d be stuck with redownloading it to test.