You might encounter issues while using JDK 7 with weblogic 12 please follow below steps to make it working.
Prior to installing JDK 7 for use with WebLogic Server, review the following issues that you may encounter when using JDK 7:
In some cases, the new JVM requires more PermGen space, which can cause PermGen errors. If this occurs, use one of the following two options to resolve the issue:
If you are using the java command to start WebLogic Server, include the following option in the command:
If you are using startWebLogic.sh (UNIX) or startWebLogic.cmd (Windows) to start WebLogic Server, prior to issuing the command, set the MEM_ARGS environment variable as follows:
USER_MEM_ARGS="-Xms32m -Xmx200m -XX:MaxPermSize=350m" export USER_MEM_ARGS
set USER_MEM_ARGS=-Xms32m -Xmx200m -XX:MaxPermSize=350m
Classes may have been removed that are from the internal package sun.*, or that have been marked as deprecated in a previous version of the JVM. If an application uses these removed methods, a ClassNotFound exception will occur.
JDBC 4.1 methods are not currently supported in WebLogic Server with JDK 7. Calls to these methods will result in an SQLException indicating that the method is not supported.
Before installing WebLogic Server, perform the following steps:
Download the appropriate JDK 7 for your platform from the following URL:
Install the JDK.
Set JAVA_HOME to point to the installed JDK 7.
Set PATH to point to $JAVA_HOME/bin.
When installing WebLogic Server: select a Custom installation. For the JDK selection, deselect the bundled JDK entries and under the Local JDK section browse and select the JAVA_HOME directory.
On the Choose Install Type screen, select the Custom option.
On the JDK Selection screen, deselect the bundled JDK entries, and then under the Local JDK section, browse to and select the JAVA_HOME directory.
After installing WebLogic Server, copy the following files from WL_HOME/modules to JAVA_HOME/jre/lib/endorsed, where WL_HOME is the WebLogic Server installation home directory:
javax.annotation_126.96.36.199_1-0.jar javax.xml.bind_2.1.1.jar javax.xml.ws_2.1.1.jar