Reference: Connection Requirements for Oracle's Type 2 JDBC Drivers (OCI)

When you create connections using Oracle's JDBC/OCI drivers, be aware of the following platform-specific requirements:

You must have the required native libraries (.dll files on Windows, and .so/.sl files on UNIX).

With the Oracle Type 2 driver (JDBC/OCI), the version of the JDBC driver must match the version of the Oracle Home. For example, the Oracle JDBC Driver version 9.0.1 requires that the Oracle Home contain version 9.0.1 of the ocijdbc9.dll, as well as the Oracle Network software and Required Support Files.

If you are connecting to a local database which is a different version from the JDBC driver you are using, then you must install the Oracle client software into a separate Oracle Home, and connect via the Oracle Net Listener.
You must place the ORACLE_HOME directory in which the client-side file for the required native libraries resides listed in your PATH environment variable.
- On Windows: List the %ORACLE_HOME%\bin directory in which the client-side DLL file resides in your PATH environment variable.
  
  If you have multiple Oracle Homes installed on your machine, use the Oracle Home Switch utility to choose the correct Oracle Home.
- On UNIX: List the ${ORACLE_HOME}/lib directory in which the client-side .so/.sl file resides in your PATH environment variable.
If your Oracle Home for the OCI driver is not the same as the Oracle Home in which JDeveloper is installed, you must either set the ORACLE_HOME environment variable.
If your Oracle Home for the OCI driver is not the same as the Oracle Home in which JDeveloper is installed and you have no other OCI drivers listed in java.library.path, you can edit {$ORACLE_HOME}/jdev/bin/jdev.conf with a line similar to the following, replacing the path shown with the full path to your Oracle Home:
- On Windows: AddNativeCodePath C:/ORACLE/ORA90/BIN
- On UNIX: AddNativeCodePath /u01/app/oracle/product/9.0.1/lib
AddNativeCodePath adds to java.library.path the directory name in which the Java VM searches for shared libraries.

Note: Because AddNativeCodePath only appends the directory to the path, if you have an OCI driver path already in the PATH environment variable, set ORACLE_HOME instead of editing PATH with AddNativeCodePath.