SingletonScopeContext.java

/*
 * Copyright 2013 Harald Wellmann
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied.
 *
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.ops4j.pax.cdi.extension.impl.context;

import java.lang.annotation.Annotation;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import javax.enterprise.context.spi.AlterableContext;
import javax.enterprise.context.spi.Contextual;
import javax.enterprise.context.spi.CreationalContext;
import javax.enterprise.inject.Typed;
import javax.enterprise.inject.spi.BeanManager;

import org.ops4j.pax.cdi.api.SingletonScoped;

/**
 * Custom CDI context for OSGi service components with singleton scope.
 *
 * @author Harald Wellmann
 *
 */
@Typed()
public class SingletonScopeContext implements AlterableContext {

    private Map<Contextual<?>, SingletonScopeContextEntry<?>> serviceBeans = new ConcurrentHashMap<>();
    private CreationalContext<Object> cc;

    /**
     * Creates the singleton scope context for the current bean bundle.
     *
     * @param beanManager
     *            bean manager of current bundle
     */
    public SingletonScopeContext(BeanManager beanManager) {
        this.cc = beanManager.createCreationalContext(null);
    }

    @Override
    public Class<? extends Annotation> getScope() {
        return SingletonScoped.class;
    }

    @SuppressWarnings({ "rawtypes", "unchecked" })
    @Override
    public <T> T get(Contextual<T> component, CreationalContext<T> creationalContext) {
        SingletonScopeContextEntry serviceBean = serviceBeans.get(component);
        if (serviceBean != null) {
            return (T) serviceBean.getContextualInstance();
        }

        T instance = component.create(creationalContext);
        serviceBean = new SingletonScopeContextEntry(component, instance, creationalContext);
        serviceBeans.put(component, serviceBean);

        return instance;
    }

    @SuppressWarnings({ "rawtypes", "unchecked" })
    @Override
    public <T> T get(Contextual<T> component) {
        SingletonScopeContextEntry serviceBean = serviceBeans.get(component);
        if (serviceBean != null) {
            return (T) serviceBean.getContextualInstance();
        }
        return null;
    }

    @SuppressWarnings({ "rawtypes", "unchecked" })
    @Override
    public void destroy(Contextual<?> component) {
        SingletonScopeContextEntry serviceBean = serviceBeans.remove(component);
        if (serviceBean != null) {
            Object instance = serviceBean.getContextualInstance();
            serviceBean.getBean().destroy(instance, serviceBean.getCreationalContext());
        }
    }

    @Override
    public boolean isActive() {
        return true;
    }

    @SuppressWarnings({ "unchecked" })
    public <S> CreationalContext<S> getCreationalContext() {
        return (CreationalContext<S>) cc;
    }
}