public static EntityManagerFactory createEntityManagerFactory()

in java-persistence-api-1.1.1/src/main/java/javax/persistence/Persistence.java [78:140]
49 lines of code
10 McCabe index (conditional complexity)

    public static EntityManagerFactory createEntityManagerFactory(
            String persistenceUnitName,
            Map properties) {

        if (properties == null) {
            properties = Collections.EMPTY_MAP;
        }

        // start by loading a provider explicitly specified in properties. The spec
        // doesn't seem to forbid providers that are not deployed as a service
        Object providerName = properties.get(PERSISTENCE_PROVIDER_PROPERTY);
        if (providerName instanceof String) {
            EntityManagerFactory factory = createFactory(
                    providerName.toString(),
                    persistenceUnitName,
                    properties);
            if (factory != null) {
                return factory;
            }
        }
         
        //If we are deployed into an OSGi environment, leverage it
        Class<? extends PersistenceProvider> providerClass = org.apache.servicemix.specs.locator.OsgiLocator.locate(PersistenceProvider.class);
        if (providerClass != null) {
            try {
                PersistenceProvider provider = providerClass.newInstance();
                return provider.createEntityManagerFactory(persistenceUnitName,
                    properties);
            }
            catch (Exception e) {
                throw new PersistenceException("Provider error. Provider: "
                    + providerName, e);
            } 
        }

        // load correctly deployed providers
        ClassLoader loader = Thread.currentThread().getContextClassLoader();
        try {
            Enumeration<URL> providers = loader
                .getResources(PERSISTENCE_PROVIDER_SERVICE);
            while (providers.hasMoreElements()) {

                String name = getProviderName(providers.nextElement());

                if (name != null) {

                    EntityManagerFactory factory = createFactory(
                            name,
                            persistenceUnitName,
                            properties);

                    if (factory != null) {
                        return factory;
                    }
                }
            }
        }
        catch (IOException e) {
            // spec doesn't mention any exceptions thrown by this method
        }

        return null;
    }