If you already familiar with Maven you know where to put your unit tests but unfortunately there does not exist a definition like this for integration tests. There are some suggestions circulating around like src/it/java, but these are only rumors.
In this guide i suggest to put them into the same directory structure like the unit tests which means in other words src/test/java and make them distinguishable by the naming conventions, but in future Maven releases this might be changed.
The execution of integration tests is handled by the Maven Failsafe Plugin.
Integration Test of a implementation against an Interface with at least two implementations; Injection for example via guice.