When downloading a JRE/JDK you have to accept the "Oracle Binary Code License Agreement". Without accepting the license you're not able to download the package, therefore you cannot directly use
wget. Maybe this could be a problem if you want to install a JDK on a server environment without X.
With following trick you're able to download the JDK with
wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com" "http://download.oracle.com/otn-pub/java/jdk/7u25-b15/server-jre-7u25-linux-x64.tar.gz"