Get Cat id from URI

if the url like this
https://127.0.0.1/wordpress/?cat=1
I can get current cat from $_GET[‘cat’];
but if the url like this
https://127.0.0.1/wordpress/archives/category/%e6%97%85%e6%b8%b8/
can I get the cat from a build in function in wordpress?
although I also can get cat from the uri,
any one who pls tell me the build in function?
thank you very much!