/*******************************************************************************
* Copyright (c) 2010-present Sonatype, Inc.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Stuart McCulloch (Sonatype, Inc.) - initial API and implementation
*******************************************************************************/
package org.eclipse.sisu.osgi;
import org.eclipse.sisu.inject.BindingSubscriber;
import org.osgi.framework.BundleContext;
import org.osgi.framework.Constants;
import org.osgi.framework.ServiceReference;
import com.google.inject.Binder;
import com.google.inject.Binding;
import com.google.inject.Key;
import com.google.inject.Provider;
import com.google.inject.Singleton;
import com.google.inject.name.Names;
import com.google.inject.spi.BindingScopingVisitor;
import com.google.inject.spi.BindingTargetVisitor;
import com.google.inject.spi.ElementVisitor;
/**
* Service {@link Binding} backed by an OSGi {@link ServiceReference}.
*/
final class ServiceBinding<T>
implements Binding<T>, Provider<T>
{
// ----------------------------------------------------------------------
// Implementation fields
// ----------------------------------------------------------------------
private final Key<T> key;
private final T instance;
private final int rank;
// ----------------------------------------------------------------------
// Constructors
// ----------------------------------------------------------------------
ServiceBinding( final BundleContext context, final String clazzName, final int maxRank,
final ServiceReference<T> reference )
throws ClassNotFoundException
{
@SuppressWarnings( "unchecked" )
final Class<T> clazz = (Class<T>) reference.getBundle().loadClass( clazzName );
final Object name = reference.getProperty( "name" );
if ( name instanceof String && ( (String) name ).length() > 0 )
{
key = Key.get( clazz, Names.named( (String) name ) );
}
else
{
key = Key.get( clazz );
}
instance = context.getService( reference );
if ( maxRank > Integer.MIN_VALUE )
{
final int serviceRanking = getServiceRanking( reference );
rank = serviceRanking < maxRank ? serviceRanking : maxRank;
}
else
{
rank = Integer.MIN_VALUE;
}
}
// ----------------------------------------------------------------------
// Public methods
// ----------------------------------------------------------------------
public Key<T> getKey()
{
return key;
}
public Provider<T> getProvider()
{
return this;
}
public T get()
{
return instance;
}
public Object getSource()
{
return "OSGi service registry";
}
public void applyTo( final Binder binder )
{
// no-op
}
public <V> V acceptVisitor( final ElementVisitor<V> visitor )
{
return visitor.visit( this );
}
public <V> V acceptTargetVisitor( final BindingTargetVisitor<? super T, V> visitor )
{
return null;
}
public <V> V acceptScopingVisitor( final BindingScopingVisitor<V> visitor )
{
return visitor.visitScopeAnnotation( Singleton.class );
}
// ----------------------------------------------------------------------
// Local methods
// ----------------------------------------------------------------------
boolean isCompatibleWith( final BindingSubscriber<T> subscriber )
{
return key.getTypeLiteral().getRawType().equals( subscriber.type().getRawType() );
}
int rank()
{
return rank;
}
// ----------------------------------------------------------------------
// Implementation methods
// ----------------------------------------------------------------------
private static int getServiceRanking( final ServiceReference<?> reference )
{
final Object ranking = reference.getProperty( Constants.SERVICE_RANKING );
return ranking instanceof Integer ? ( (Integer) ranking ).intValue() : 0;
}
}