org.eclipse.sisu.inject.Implementations Maven / Gradle / Ivy
/*******************************************************************************
* 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.inject;
import java.lang.annotation.Annotation;
import javax.inject.Provider;
import org.eclipse.sisu.Description;
import org.eclipse.sisu.Priority;
import com.google.inject.Binding;
import com.google.inject.spi.BindingTargetVisitor;
import com.google.inject.spi.ConstructorBinding;
import com.google.inject.spi.DefaultBindingTargetVisitor;
import com.google.inject.spi.ExposedBinding;
import com.google.inject.spi.InstanceBinding;
import com.google.inject.spi.LinkedKeyBinding;
import com.google.inject.spi.ProviderInstanceBinding;
import com.google.inject.spi.ProviderKeyBinding;
import com.google.inject.spi.UntargettedBinding;
/**
* Utility methods for discovering the implementations behind Guice bindings.
*/
final class Implementations
{
// ----------------------------------------------------------------------
// Static initialization
// ----------------------------------------------------------------------
static
{
boolean hasGuiceServlet;
try
{
hasGuiceServlet = BindingTargetVisitor.class.isInstance( ServletFinder.THIS );
}
catch ( final LinkageError e )
{
hasGuiceServlet = false;
}
HAS_GUICE_SERVLET = hasGuiceServlet;
boolean hasJsr250Priority;
try
{
hasJsr250Priority = javax.annotation.Priority.class.isAnnotation();
}
catch ( final LinkageError e )
{
hasJsr250Priority = false;
}
HAS_JSR250_PRIORITY = hasJsr250Priority;
}
// ----------------------------------------------------------------------
// Constants
// ----------------------------------------------------------------------
private static final boolean HAS_GUICE_SERVLET;
private static final boolean HAS_JSR250_PRIORITY;
// ----------------------------------------------------------------------
// Constructors
// ----------------------------------------------------------------------
private Implementations()
{
// static utility class, not allowed to create instances
}
// ----------------------------------------------------------------------
// Utility methods
// ----------------------------------------------------------------------
/**
* Attempts to find the implementation behind the given {@link Binding}.
*
* @param binding The binding
* @return Implementation class behind the binding; {@code null} if it couldn't be found
*/
public static Class find( final Binding binding )
{
return binding.acceptTargetVisitor( ClassFinder.THIS );
}
/**
* Attempts to find an annotation on the implementation behind the given {@link Binding}.
*
* @param binding The binding
* @param annotationType The annotation type
* @return Annotation on the bound implementation; {@code null} if it couldn't be found
*/
public static T getAnnotation( final Binding binding, final Class annotationType )
{
final boolean isPriority = Priority.class.equals( annotationType );
final Class annotationSource =
// when looking for @Priority also consider annotations on providers (and servlets/filters if available)
binding.acceptTargetVisitor( isPriority ? ( HAS_GUICE_SERVLET ? ServletFinder.THIS : ProviderFinder.THIS )
: ClassFinder.THIS );
T annotation = null;
if ( null != annotationSource )
{
annotation = annotationSource.getAnnotation( annotationType );
if ( null == annotation )
{
if ( HAS_JSR250_PRIORITY && isPriority )
{
annotation = adaptJsr250( binding, annotationSource );
}
else if ( Description.class.equals( annotationType ) )
{
annotation = adaptLegacy( binding, annotationSource );
}
}
}
return annotation;
}
// ----------------------------------------------------------------------
// Implementation methods
// ----------------------------------------------------------------------
@SuppressWarnings( "unchecked" )
private static T adaptJsr250( final Binding binding, final Class clazz )
{
final javax.annotation.Priority jsr250 = clazz.getAnnotation( javax.annotation.Priority.class );
return null != jsr250 ? (T) new PrioritySource( binding.getSource(), jsr250.value() ) : null;
}
@SuppressWarnings( { "unchecked", "deprecation" } )
private static T adaptLegacy( final Binding binding, final Class clazz )
{
final org.sonatype.inject.Description legacy = clazz.getAnnotation( org.sonatype.inject.Description.class );
return null != legacy ? (T) new DescriptionSource( binding.getSource(), legacy.value() ) : null;
}
// ----------------------------------------------------------------------
// Implementation types
// ----------------------------------------------------------------------
/**
* {@link BindingTargetVisitor} that attempts to find the implementations behind bindings.
*/
static class ClassFinder
extends DefaultBindingTargetVisitor>
{
// ----------------------------------------------------------------------
// Constants
// ----------------------------------------------------------------------
static final BindingTargetVisitor> THIS = new ClassFinder();
// ----------------------------------------------------------------------
// Public methods
// ----------------------------------------------------------------------
@Override
public Class visit( final UntargettedBinding binding )
{
return binding.getKey().getTypeLiteral().getRawType();
}
@Override
public Class visit( final LinkedKeyBinding binding )
{
// this assumes only one level of indirection: api-->impl
return binding.getLinkedKey().getTypeLiteral().getRawType();
}
@Override
public Class visit( final ConstructorBinding binding )
{
return binding.getConstructor().getDeclaringType().getRawType();
}
@Override
public Class visit( final InstanceBinding binding )
{
return binding.getInstance().getClass();
}
@Override
public Class visit( final ProviderInstanceBinding binding )
{
return peekBehind( Guice4.getProviderInstance( binding ) );
}
@Override
public Class visit( final ExposedBinding binding )
{
return binding.getPrivateElements().getInjector().getBinding( binding.getKey() ).acceptTargetVisitor( this );
}
final Class peekBehind( final Provider provider )
{
if ( provider instanceof DeferredProvider )
{
try
{
// deferred providers let us peek at the underlying implementation type
return ( (DeferredProvider) provider ).getImplementationClass().load();
}
catch ( final TypeNotPresentException e ) // NOPMD
{
// fall-through
}
}
return null;
}
}
/**
* {@link ClassFinder} that also returns {@link Provider} implementations.
*/
static class ProviderFinder
extends ClassFinder
{
// ----------------------------------------------------------------------
// Constants
// ----------------------------------------------------------------------
@SuppressWarnings( "hiding" )
static final BindingTargetVisitor> THIS = new ProviderFinder();
// ----------------------------------------------------------------------
// Public methods
// ----------------------------------------------------------------------
@Override
public Class visit( final ProviderInstanceBinding binding )
{
final Provider provider = Guice4.getProviderInstance( binding );
final Class providedClass = peekBehind( provider );
return null != providedClass ? providedClass : provider.getClass();
}
@Override
public Class visit( final ProviderKeyBinding binding )
{
return binding.getProviderKey().getTypeLiteral().getRawType();
}
}
/**
* {@link ProviderFinder} that also returns servlet/filter implementations.
*/
static final class ServletFinder
extends ProviderFinder
implements com.google.inject.servlet.ServletModuleTargetVisitor>
{
// ----------------------------------------------------------------------
// Constants
// ----------------------------------------------------------------------
@SuppressWarnings( "hiding" )
static final BindingTargetVisitor> THIS = new ServletFinder();
// ----------------------------------------------------------------------
// Public methods
// ----------------------------------------------------------------------
public Class visit( final com.google.inject.servlet.InstanceFilterBinding binding )
{
return binding.getFilterInstance().getClass();
}
public Class visit( final com.google.inject.servlet.InstanceServletBinding binding )
{
return binding.getServletInstance().getClass();
}
public Class visit( final com.google.inject.servlet.LinkedFilterBinding binding )
{
// this assumes only one level of indirection: api-->impl
return binding.getLinkedKey().getTypeLiteral().getRawType();
}
public Class visit( final com.google.inject.servlet.LinkedServletBinding binding )
{
// this assumes only one level of indirection: api-->impl
return binding.getLinkedKey().getTypeLiteral().getRawType();
}
}
}