/WEB-INF/classes vs /WEB-INF/lib

Question

I\'d like to package my Java EE6 web classes (beans, filters, servlets) into jar and place it into /WEB-INF/lib/ directory along with other utility

Answer 1

I'd go for /WEB-INF/classes. It allows you to run your application in debug mode and hot-swap classes on change. If you package everything as a jar, you'd have to repackage and redeploy the app every time you change a class.

Answer 2

In Tomcat Servlet container's definition: WEB-INF\classes is searched before WEB-INF\lib. You can choose to delegate your classloading to your custom classloader - even then the order above is maintained.

If you choose to go with a different provider e.g. JBOss, Glassfish, Jetty it might have a different order, but I am not sure about those.

Answer 3

Well, shortly: Imagine you have class org.example.Test.class, if you put it into jar and in WEB-INF/lib/ directory, and copy the same class into WEB-INF/classes/ then classloader of that application will use last one (from WEB-INF/classes/).

Sometimes you can use it as advantage - I have a library, and it has a bug... I look for source of that class (where bug is; I miss the part of how I know that bug is in that class, that's another story), I add that class to the project with fixed code, and it is compiled into WEB-INF/classes/ while library still exist in WEB-INF/lib/. Fixed class will be used until library will be fixed.