Oracle JDBC Driver for java oracle.jdbc.driver.OracleDriver ojdbc7 Patched JDBC Thin driver that supports TLSv1.1 and TLSv1.2 protocols compiled with "javac -g" and contains tracing code.
Download JD-GUI to open JAR file and explore Java source code file (.class .java)
Click menu "File → Open File..." or just drag-and-drop the JAR file in the JD-GUI window oracle-driver-ojdbc_g-12.1.0.2.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.