As you want to update weblogic and jdk version 1.7 to 1.8,. Then you can uninstall both of them. Then download weblogic 12.2.1 and jdk 8 from following link. Weblogic download link: JDK8 download link:.
Then install JDK8 first and then weblogic. Hope it is easy.,. WebLogic 12.2.1 requires Java 8 (JDK 8) as a runtime. WebLogic 12.1.3 can be used with Java 7 or Java 8. Using WebLogic 12.1.3 with Java 7 caused warnings because of the permspace settings in the WebLogic start scripts.
Home » Articles » 11g » Here Oracle WebLogic Server 11gR1 (10.3.5) Installation on Windows (32-bit) This article describes the default installation of Oracle.
Oracle Weblogic Server Tutorial
Permspace is removed from JDK 8, so also these warnings are gone now with WebLogic 12.2.1 and JDK8. JDK 8 comes with Nashorn JavaScript engine. Try the jjs command line tool. You can also follow the link.