org.ualerts.testing.jpa.EntityManagerFactoryUtil.java Source code

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Here is the source code for org.ualerts.testing.jpa.EntityManagerFactoryUtil.java

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/*
 * File created on May 8, 2013
 *
 * Copyright 2008-2013 Virginia Polytechnic Institute and State University
 *
 * 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.ualerts.testing.jpa;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.PersistenceException;

import org.apache.commons.io.IOUtils;

/**
 * Static utility methods that provide support creating an 
 * {@link EntityManagerFactory}.
 *
 * @author Carl Harris
 */
public final class EntityManagerFactoryUtil {

    /**
     * The property name of the persistence unit.
     */
    public static final String PERSISTENCE_UNIT_PROPERTY = "persistence.unit";

    /**
     * Default of the persistence test properties resource.
     */
    public static final String DEFAULT_PROPERTIES_RESOURCE = "persistence-test.properties";

    private static final String DEFAULT_PERSISTENCE_UNIT_NAME = "unspecified-persistence-unit";

    private static Map<String, EntityManagerFactory> factoryMap = new HashMap<String, EntityManagerFactory>();

    private EntityManagerFactoryUtil() {
    }

    /**
     * Creates a new {@code EntityManagerFactory} configured using the 
     * properties specified in the default properties resource.
     * @return factory object
     * @throws Exception
     * @see {@link #DEFAULT_PROPERTIES_RESOURCE}
     */
    public static EntityManagerFactory createEntityManagerFactory() throws IOException, PersistenceException {
        return createEntityManagerFactory(DEFAULT_PROPERTIES_RESOURCE);
    }

    /**
     * Creates a new {@code EntityManagerFactory} configured using the 
     * properties specified in the given resource.
     * @param propertiesResource a class path resource containing properties
     * @return factory object
     * @throws IOException
     * @throws PersistenceException
     */
    public static EntityManagerFactory createEntityManagerFactory(String propertiesResource)
            throws IOException, PersistenceException {

        if (factoryMap.containsKey(propertiesResource)) {
            EntityManagerFactory emf = factoryMap.get(propertiesResource);
            if (emf.isOpen()) {
                return emf;
            }
        }

        Properties properties = loadProperties(propertiesResource);
        String persistenceUnit = properties.getProperty(PERSISTENCE_UNIT_PROPERTY, DEFAULT_PERSISTENCE_UNIT_NAME);

        factoryMap.put(propertiesResource,
                createEntityManagerFactory(properties, persistenceUnit, propertiesResource));

        return factoryMap.get(propertiesResource);
    }

    private static EntityManagerFactory createEntityManagerFactory(Properties properties, String unit,
            String propertiesResource) throws PersistenceException {
        try {
            return Persistence.createEntityManagerFactory(unit, properties);
        } catch (PersistenceException ex) {
            System.err.println("Cannot create persistence unit '" + unit + "'.");
            System.err.println("Make sure the '" + PERSISTENCE_UNIT_PROPERTY + "' property is specified in "
                    + propertiesResource);
            System.err.println("and try cleaning the project.");
            throw ex;
        }
    }

    private static Properties loadProperties(String propertiesResource) throws IOException {
        InputStream inputStream = getResourceAsStream(propertiesResource);
        try {
            Properties properties = new Properties();
            properties.load(inputStream);
            return properties;
        } finally {
            IOUtils.closeQuietly(inputStream);
        }
    }

    private static InputStream getResourceAsStream(String propertiesResource) throws FileNotFoundException {
        InputStream inputStream = EntityManagerFactoryUtil.class.getClassLoader()
                .getResourceAsStream(propertiesResource);
        if (inputStream == null) {
            System.err.println("Cannot find resource '" + propertiesResource + "' at the root of the classpath.");
            System.err.println("Make sure the resource exists and " + "try cleaning the project.");
            throw new FileNotFoundException(propertiesResource);
        }
        return inputStream;
    }

}