Get the record Id from the URL

Hi Guys,

I need to get the ID from the URL and redirect the page into my community site. Below is the URL
https://fidel-castro.cs20.force.com/community/a04m00000090VcV?fromEmail=1&s1oid=00Dm00000002bhR&s1nid=0DBj00000008Oz9&s

There is class written for URL rewrite. Can anyone help me?

Thanks.
Vetri