PersistenceConfigurationFactory.java

package org.needle4j.db.configuration;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;

/**
 * Factory to create and access the configured persistence context.
 */
public final class PersistenceConfigurationFactory implements PersistenceConfiguration {

    private static final Map<PersistenceConfigurationFactory, PersistenceConfiguration> PERSISTENCE_MAP = new HashMap<PersistenceConfigurationFactory, PersistenceConfiguration>();

    private String persistenceUnit;
    private Class<?>[] cfgClazzes;

    public PersistenceConfigurationFactory(final String persistenceUnit) {
        super();
        this.persistenceUnit = persistenceUnit;
    }

    public PersistenceConfigurationFactory(final Class<?>[] cfgClazzes) {
        super();
        this.cfgClazzes = Arrays.copyOf(cfgClazzes, cfgClazzes.length);
    }

    private PersistenceConfiguration getPersistenceConfiguration() {
        return getPersistenceConfiguration(this);
    }

    String getPersistenceUnit() {
        return persistenceUnit;
    }

    Class<?>[] getCfgClazzes() {
        return cfgClazzes;
    }

    /**
     * Returns the {@link EntityManager} instance which is associated with the
     * configured persistence context.
     * 
     * @return {@link EntityManager}
     */
    @Override
    public EntityManager getEntityManager() {
        return getPersistenceConfiguration().getEntityManager();
    }

    /**
     * Returns the {@link EntityManagerFactory}.
     * 
     * @return {@link EntityManagerFactory}
     */
    @Override
    public EntityManagerFactory getEntityManagerFactory() {
        return getPersistenceConfiguration().getEntityManagerFactory();
    }

    private static PersistenceConfiguration getPersistenceConfiguration(
            final PersistenceConfigurationFactory configuration) {
        PersistenceConfiguration result = PERSISTENCE_MAP.get(configuration);

        if (result == null) {
            result = createPersistenceConfiguration(configuration);
            PERSISTENCE_MAP.put(configuration, result);
        }

        return result;
    }

    private static PersistenceConfiguration createPersistenceConfiguration(
            final PersistenceConfigurationFactory configuration) {
        if (configuration.getPersistenceUnit() != null) {
            return new PersistenceUnitConfiguration(configuration.getPersistenceUnit());
        } else if (configuration.getCfgClazzes() != null) {
            return new EJB3Configuration(configuration.getCfgClazzes());
        }

        return null;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + Arrays.hashCode(cfgClazzes);
        result = prime * result + ((persistenceUnit == null) ? 0 : persistenceUnit.hashCode());
        return result;
    }

    @Override
    public boolean equals(final Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final PersistenceConfigurationFactory other = (PersistenceConfigurationFactory) obj;
        if (!Arrays.equals(cfgClazzes, other.cfgClazzes)) {
            return false;
        }
        if (persistenceUnit == null) {
            if (other.persistenceUnit != null) {
                return false;
            }
        } else if (!persistenceUnit.equals(other.persistenceUnit)) {
            return false;
        }
        return true;
    }

}