We have a small project with some heavy-weight dependencies (e.g. Spring) of which we only use small parts. Therefore, the JAR we get when packing with all dependencies weighs several megabytes, even for out two-class-server. This seems unnecessary.
Is there a way to restrict JAR assembly to actually used (class) files?
You can use the maven-shade-plugin to create a Jar-with-dependencies (your project and the dependencies merged into one big jar) while limiting the classes or packages that are added to that jar. See the includes / excludes page for reference.
If you don't want to manually specify what needs to be included, perhaps there is a way to integrate ProGuard with your build.
It's not possible to include only classes which are used. But you can exclude dependencies from your depencies to reduce the JAR size. Only drawback: you need to know what you can exclude and what not.
来源：https://stackoverflow.com/questions/6957760/exclude-unused-parts-of-dependencies-from-jar-maven