As far as I know, the streams API does not support asynchronous event processing. Sounds like you want something like Reactive Extensions for .NET, and there is a Java port of it called RxJava, created by Netflix.
RxJava supports many of the same high-level operations as Java 8 streams (such as map and filter) and is asynchronous.
Update: There is now a reactive streams initiative in the works, and it looks like JDK 9 will include support for at least part of it though the Flow class.