将RoboGuice上下文注入与AbstractThreadedSyncAdapter一起使用

Question

I am using RoboGuice 2.0b4 to wire up my Android application, which makes use of a SyncAdapter (derived from AbstractThreadedSyncAdapter) hosted in a regular service:

@ContextSingleton
public class SyncAdapter extends AbstractThreadedSyncAdapter {
    @Inject
    private AccountManager accountManager;

    @Inject
    public SyncAdapter(Context context) {
        super(context, true, false);

        Injector injector = RoboGuice.getInjector(context);
        ContextScope scope = injector.getInstance(ContextScope.class);
        synchronized(ContextScope.class) {
            scope.enter(context);
            try {
                injector.injectMembers(this);
            } finally {
                scope.exit(context);
            }
        }
    }
    [...]
}


@ContextSingleton
public class SynchronizationService extends RoboService {
    @Inject
    private SyncAdapter syncAdapter;

    @Override
    public IBinder onBind(Intent intent) {
        if (equal("android.content.SyncAdapter", intent.getAction())) {
            return syncAdapter.getSyncAdapterBinder();
        } else [...]
        }
        return null;
    }
}

Unfortunately, RoboGuice bails out during the dependency injection when it becomes recursive while calling scope.enter from the SyncAdapter 's constructor:

java.lang.IllegalArgumentException: Scope for com.example.SynchronizationService@412c65b0 must be closed before scope for com.example.SynchronizationService@412c65b0 may be opened

when it sees the context attached to the current thread by the onCreate call of SynchronizationService . Stack trace:

  at roboguice.inject.ContextScope.enter(ContextScope.java:67)
  at roboguice.inject.ContextScopedRoboInjector.getInstance(ContextScopedRoboInjector.java:141)
  at com.example.SyncAdapter.<init>(SyncAdapter.java:65)
  at java.lang.reflect.Constructor.constructNative(Constructor.java:-1)
  at java.lang.reflect.Constructor.newInstance(Constructor.java:417)
  at com.google.inject.internal.DefaultConstructionProxyFactory$1.newInstance(DefaultConstructionProxyFactory.java:85)
  at com.google.inject.internal.ConstructorInjector.construct(ConstructorInjector.java:85)
  at com.google.inject.internal.ConstructorBindingImpl$Factory.get(ConstructorBindingImpl.java:254)
  at com.google.inject.internal.ProviderToInternalFactoryAdapter$1.call(ProviderToInternalFactoryAdapter.java:46)
  at com.google.inject.internal.InjectorImpl.callInContext(InjectorImpl.java:1031)
  at com.google.inject.internal.ProviderToInternalFactoryAdapter.get(ProviderToInternalFactoryAdapter.java:40)
  at roboguice.inject.ContextScope$1.get(ContextScope.java:126)
  at com.google.inject.internal.InternalFactoryToProviderAdapter.get(InternalFactoryToProviderAdapter.java:40)
  at com.google.inject.internal.SingleFieldInjector.inject(SingleFieldInjector.java:53)
  at com.google.inject.internal.MembersInjectorImpl.injectMembers(MembersInjectorImpl.java:110)
  at com.google.inject.internal.MembersInjectorImpl$1.call(MembersInjectorImpl.java:75)
  at com.google.inject.internal.MembersInjectorImpl$1.call(MembersInjectorImpl.java:73)
  at com.google.inject.internal.InjectorImpl.callInContext(InjectorImpl.java:1024)
  at com.google.inject.internal.MembersInjectorImpl.injectAndNotify(MembersInjectorImpl.java:73)
  at com.google.inject.internal.MembersInjectorImpl.injectMembers(MembersInjectorImpl.java:60)
  at com.google.inject.internal.InjectorImpl.injectMembers(InjectorImpl.java:944)
  at roboguice.inject.ContextScopedRoboInjector.injectMembersWithoutViews(ContextScopedRoboInjector.java:243)
  at roboguice.inject.ContextScopedRoboInjector.injectMembers(ContextScopedRoboInjector.java:236)
  at roboguice.service.RoboService.onCreate(RoboService.java:57)
  at android.app.ActivityThread.handleCreateService(ActivityThread.java:2253)
  [...]
  at dalvik.system.NativeStart.main(NativeStart.java:-1)

So, apparently, RoboGuice's dependency injection is not reentrant.

Unfortunately, a SyncAdapter needs constructor-based injection as AbstractThreadedSyncAdapter expects a context to be supplied to its constructor.

Any ideas? I might hack RoboGuice to allow for reentrance, but that's probably not a light undertaking, so I'd prefer a less invasive workaround. ;-)

Answer 1

Looks like this is actually a bug in RoboGuice. Fortunately, the bug filed in its issue tracker even comes with a patch: http://code.google.com/p/roboguice/issues/detail?id=179