Sometimes it is useful to add a plain JAR file to the build-time dependencies of a project. For example we may want to use a “pure” API JAR to build against, but use a different artefact at runtime. Or we may be planning to embed the dependency in our bundle.
Plain JAR files should be added to the Build Path using the version=file attribute. Unfortunately there is currently no GUI support for this attribute so you will have to edit the Source tab:
-buildpath: libs/servlet-api-3.0.jar;version=file
Note that this approach is better than using Eclipse’s Add to Build Path action, because the latter will not be visible when the project is built offline using ANT; i.e. a project that compiles in Eclipse may not compile in ANT. Using the -buildpath approach ensures that both Eclipse and ANT build the project in exactly the same way.