javax.persistence.EntityManagerFactory#isOpen ( )源码实例Demo

public static void close() throws Exception {
	try {
		if (instance != null) {
			for (EntityManagerFactory emf : instance.entityManagerFactoryMap.values()) {
				if (emf.isOpen()) {
					emf.close();
				}
			}
			instance.entityManagerFactoryMap.clear();
			instance.checkPersistFieldMap.clear();
			instance.checkRemoveFieldMap.clear();
		}
		/* 注销驱动程序 */
		Enumeration<Driver> drivers = DriverManager.getDrivers();
		while (drivers.hasMoreElements()) {
			Driver driver = drivers.nextElement();
			DriverManager.deregisterDriver(driver);
		}
		/* 由于可能重新载入 */
		instance = null;
	} catch (Exception e) {
		throw new Exception("close error.", e);
	}
}
 

/**
 *
 */
public void fill() throws JRException
{
	long start = System.currentTimeMillis();
	// create entity manager factory for connection with database
	EntityManagerFactory emf = Persistence.createEntityManagerFactory("pu1", new HashMap<Object, Object>());
	EntityManager em = emf.createEntityManager();

	try
	{
		Map<String, Object> parameters = getParameters(em);
		
		JasperFillManager.fillReportToFile("build/reports/JRMDbReport.jasper", parameters);

		em.close();
		
		System.err.println("Filling time : " + (System.currentTimeMillis() - start));
	}
	finally
	{
		if (em.isOpen())
			em.close();
		if (emf.isOpen())
			emf.close();
	}
}
 

public void setUp() throws Exception {
  super.setUp();
  final EntityManagerFactory emf = getEntityManagerFactory();
  if (emf == null || !emf.isOpen() || lastTestClass != getClass()) {
    setEntityManagerFactory(createEntityManagerFactory());
    lastTestClass = getClass();
  }
}