2009/11/2 Clemens Eisserer <linuxhi...@gmail.com>: > Hi, > > I am trying to install my own RenderingEngine implementation, however > I am not accustomed to the ServiceLoader concept: > >> ServiceLoader<RenderingEngine> reLoader = >> ServiceLoader.loadInstalled(RenderingEngine.class); > > the ServiceLoader doesn't e.g. contain my CairoRenderingEngine. > > Would it be enough to simply create a META-INF directory with a single > file in it, similar to what has been done for pisces? > Is there any way to influence the iteration-order? > If possible I would prefer my RendeingEngine to be tried before Pisces > when its mature and complete, at least it should be configureable > without passing the cmd-line parameter every time. > > Whats the purpose of the ServiceLoader, wouldn't it be possible to > simply load the class specified on the command-line directly? > > Thank you in advance, Clemens >
http://java.sun.com/javase/6/docs/api/java/util/ServiceLoader.html You need a text file in META-INF/services/<package name>.RenderingEngine which lists the provided implementations. loadInstalled uses the extension class loader so that resources needs to be loadable by that classloader. I presume this means it needs to be available in ${JAVA_HOME}/jre/lib/ext. You seem to contradict yourself, you want it to be 'configurable without passing the command-line parameter every time' but then ask why we can't simply load a class specified on the command-line. The job of ServiceLoader and the META-INF/services files is to facilitate exactly what you appear to want -- configuring things once and having the service loaded on normal java invocations. As to ordering, you can make sure your engine is first in this list at least, but that is affected by caching and the time it takes to load a class. -- Andrew :-) Free Java Software Engineer Red Hat, Inc. (http://www.redhat.com) Support Free Java! Contribute to GNU Classpath and the OpenJDK http://www.gnu.org/software/classpath http://openjdk.java.net PGP Key: 94EFD9D8 (http://subkeys.pgp.net) Fingerprint: F8EF F1EA 401E 2E60 15FA 7927 142C 2591 94EF D9D8
