/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 jars and abandon /WEB-INF/classes/ directory totally.

Are there any substantial differences between the two in terms of classloading, acessing application context, etc?

Thanks.

PS: Whenever googling any of java specs I'm always redirected to Oracle documentation index which is dozen clicks away from original url. Anyone knows what's happening there?

Related: https://stackoverflow.com/questions/8364619/web-inf-classes-vs-web-inf-lib-jar-in-classpath-priority `WEB-INF/classes/ vs WEB-INF/lib/*.jar in classpath priority?` — StackzOfZtuff, Nov 18 '21 at 11:42

score 23 · Accepted Answer · answered Jan 19 '11 at 18:52

23

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.

answered Jan 19 '11 at 18:52

Bozho

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thanks. But, aside from debugging, will it be functionally the same app? – andbi Jan 19 '11 at 18:59

score 18 · Answer 2 · answered Jan 19 '11 at 18:54

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.

Thanks, this feature may be helpful. – andbi Jan 19 '11 at 19:02 — andbi, Jan 19 '11 at 19:02

score 2 · Answer 3 · answered Sep 25 '17 at 16:22

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.

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

3 Answers3

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