Install jdk 8 without admin privileges
You can use Pacifist to view the contents of the JDK installer package. You can use it to extract the files to your user library folder ~/Library instead of the system wide /Library.

The relevant subfolders in Library are Internet Plug-Ins, Java, and an alias in PreferencePanes.

See this screenshot for the path structure.



Moving the files can be done manually or by modifying the installer package.