deltaspike/core/api/src/main/java/org/apache/deltaspike/core/api/provider/DependentProvider.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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.apache.deltaspike.core.api.provider;

import javax.enterprise.context.spi.CreationalContext;
import javax.enterprise.inject.spi.Bean;
import javax.enterprise.inject.spi.PassivationCapable;
import javax.inject.Provider;

import java.io.IOException;
import java.io.NotSerializableException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

/**
 * A {@link Provider} for @Dependent scoped contextual instances. We need this to be able to properly clean them up
 * when they are not needed anymore via the {@link #destroy()} method.
 *
 * Instances of this class can be retrieved using the {@link BeanProvider}.
 *
 * Instances of this class are Serializable if the wrapped contextual instance is Serializable.
 *
 * @see BeanProvider#getDependent(java.lang.Class, java.lang.annotation.Annotation...)
 */
public class DependentProvider<T> implements Provider<T>, Serializable
{
    private static final long serialVersionUID = 23423413412001L;

    private T instance;
    private CreationalContext<T> creationalContext;
    private transient Bean<T> bean;

    DependentProvider(Bean<T> bean, CreationalContext<T> creationalContext, T instance)
    {
        this.bean = bean;
        this.creationalContext = creationalContext;
        this.instance = instance;
    }

    @Override
    public T get()
    {
        return instance;
    }

    /**
     * This method will properly destroy the &#064;Dependent scoped instance.
     * It will have no effect if the bean is NormalScoped as those have their
     * own lifecycle which we must not disrupt.
     */
    public void destroy()
    {
        if (!BeanManagerProvider.getInstance().getBeanManager().isNormalScope(bean.getScope()))
        {
            bean.destroy(instance, creationalContext);
        }
    }

    private void writeObject(ObjectOutputStream out) throws IOException
    {
        if (!(bean instanceof PassivationCapable))
        {
            throw new NotSerializableException("Bean is not PassivationCapable: " + bean.toString());
        }
        String passivationId = ((PassivationCapable) bean).getId();
        if (passivationId == null)
        {
            throw new NotSerializableException(bean.toString());
        }

        out.writeLong(serialVersionUID);
        out.writeObject(passivationId);
        out.writeObject(instance);
        out.writeObject(creationalContext);
    }

    @SuppressWarnings("unchecked")
    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException
    {
        long oldSerialId = in.readLong();
        if (oldSerialId != serialVersionUID)
        {
            throw new NotSerializableException(getClass().getName() + " serialVersion does not match");
        }
        String passivationId = (String) in.readObject();
        bean = (Bean<T>) BeanManagerProvider.getInstance().getBeanManager().getPassivationCapableBean(passivationId);
        instance = (T) in.readObject();
        creationalContext = (CreationalContext<T>) in.readObject();
    }

}