when u find out an error Cannot load JDBC driver class 'oracle.jdbc.OracleDriver' in tomcat web application container

you can solve this error doing the following steps:

1. download the oracle driver appropriately when you have not the driver
2. copy the driver at ${CATALINA_HOME}/common/lib
3. (optional) remove any oracle driver which placed in web application classpath (yourAppContext/WEB-INF/lib)
4. running tomcat