Tapping into Stripes - Stripes...and Java Web Development is Fun Again - page 289

private static Injector injector;
private static final Log log =
Log.getInstance(GuiceInterceptor. class );
public void init(Configuration config) throws Exception {
List<Class<? extends Module>> moduleClasses =
config.getBootstrapPropertyResolver()
.getClassPropertyList(MODULES, Module. class );
int size = moduleClasses.size();
if (size > 0) {
List<Module> modules = new ArrayList<Module>(size);
for (Class<? extends Module> cls : moduleClasses) {
modules.add(cls.newInstance());
}
injector = Guice.createInjector(modules);
log.info("Created Guice injector with modules: ",
moduleClasses);
}
else {
injector = Guice.createInjector();
}
}
public static Injector getInjector() {
return injector;
}
}
What this does is look for a list of Module classes configured in web.xml
as an init parameter to the Stripes filter with the name Guice.Modules . If
there is no such parameter, then Stripes looks for classes that imple-
ment Module in the extension packages. That way, we have the option
of using an extension package or a parameter in web.xml , just like all
the other Stripes extensions.
Once we have the list of Module classes, it's simple to create instances
and use them to configure the Guice injector. We then use the injector
in the intercept ( ) method that we wrote earlier to inject dependencies in
the action bean context and in the action bean. The injector is in a static
member to give easy access to it via GuiceInterceptor.getInjector ( ), but
otherwise it wouldn't need to be since Stripes creates only one instance
of each interceptor.
Now that we have defined the Guice configuration and implemented the
Guice interceptor, we can use dependency injection on action beans
and the action bean context by tagging properties with Guice's @Inject
annotation.