Understanding imported WAR in Eclipse and its folder structure

Question

I have just imported a WAR file from an external site, which is basically a servlet into Eclipse IDE (the project runs on Apache-Tomcat).

When I import it it has a folder called Web App Libraries. So here are a few of my newbie questions:

1. I am unsure about what the exact purpose is of this folder is? What does it do, why would you choose to have it in your project?

2. I see that it has a folder called Improted Classes and foobar.class files inside it - why?
   (These seemed to be mirrored in Web Content folder - although here you can modify the code as they are foobar.java.)

3. There are references to foobar.jar files too - these are also mirrored in WEB-INF/lib folder too - why?

I know these are basic type questions but I'm just getting to grips with Java and website dev, so apologies if they sound a bit dumb! - BTW if anyone knows any good online resource to understand more about project file structures like this, then let me know. I just need to get to grips with this stuff asap - as the project deadline is fairly soon.

Cheers.

Here's a screenshot just to help you visualise:

Answer 1

I assume this is a screenshot from the 'Project Explorer' view. It does not display exact folders and files structure, is adds a few candy constructed from project's metadata.

• To see real structure of your project, try switching to the 'Navigator' view.
• During a WAR file import, Eclipse basically does two things:
  • Creates a new web project and copies WAR's content to 'WebContent' subfolder of the new project.
  • Based on the WAR, it constructs project's metadata (.project and .classpath files).
• The 'Web App Libraries' section displays list of jar files that the WAR contained (in WEB-INF/lib
• 'Imported classes' (which I also see for a first time) seem to contain classes found in the imported WAR (WEB-INF/classes), for which Eclipse was not able to find any corresponding source files. To fix this, create a new Java source folder in the project and move the classes you now have in 'firstResource' folder to it.

Answer 2

Web App Libraries isn't a real directory, but rather a listing of what Eclipse thinks are this project's libraries.

Generally, this consists of all the jar files in WebContent/WEB-INF/lib/

Sometimes, Eclipse no longer lists them in their real directory in Eclipse's Package Explorer... but they're still there if you look with another program.