Some necessary libraries are missing in WAR-File after export from Eclipse - why?

I took over a project of a college which contains some web services and by exporting the project as WAR-file some libraries are contained in the file (e.g. Axis2) and some aren’t (hibernate, JDBC driver). Also a jar which is added to the c开发者_如何学JAVAlass path has not been exported. All libraries are located in folders on the hard drive which means that they are not in located somewhere in the eclipse folder. If I open the WAR-file after export with WinRAR and add the libraries manually to the file the web service will work well but that is not a good solution… What could be the reason for that problem? And how can I solve it?

The jar dependencies for Eclipse to include in a war file not placed in WEB-INF/lib is not managed by the usual "project export/imports" but by a separate panel (3.6: Deployment Assembly, 3.5: Java EE Module Dependencies) in the preferences of the dynamic web project.

Note: Since the answer was originally written, Maven has become the defacto packaging tool. Instead of relying on Eclipse features, I would strongly recommend to use Maven packaging instead. It has the additional benefit of making the project instantly usable with all modern IDE's.