Design

1. Credit card number in log should show only last four digits eg: xxxxxxxxxxxx1234
2. Configuration Setting should go in .properties, if you configure in context.xml every time you need to restart you server after updating xml
3. Should close DB, file etc properly
4. Avoid writing System.out.println() statement in loops.
5. In production log level should  be in INFO or WARN - it might decrease performance of the application due to many file IO operation try to write optimized text in logs.