I am currently building an application using Tomcat, Spring and JAVA. I am using Log4J as my logging library. I currently am logging everything to a text file
You can try redirecting the StdErr to use your logger. This should output the result of anything being written to your std err (which should include unhandled exceptions)
This blog post gives a good rundown on how to do the redirection into a FileHandler that is apart of your logger: