How do I know if my EntityManager is using a JTA or RESOURCE_LOCAL data source?

Question

I have a utility class as shown below. I want to be able to use this class with RESOURCE_LOCAL or JTA storage units. If I change persistence.xml from JTA to RESOURCE_LOCAL, I will not need to change the code.

I tried using EntityManager.getTransaction () to find out if there is an active transaction, but calling getTransaction () throws an exception if using JTA. I could combine the getTransaction () call with try / catch, but I don't want to resort to exception handling for this. EntityManager.getProperties () does not show anything that points to JTA or RESOURCE_LOCAL

I need to somehow indicate which type of continuity unit the EntityManager (or EntityManagerFactory) uses in the code below.

public class CredentialsUtil {

public static final String VGBD_PU = "VGDBpu";
static Logger logger = Logger.getLogger(CredentialsUtilStatic.class);
static EntityManagerFactory emf = Persistence.createEntityManagerFactory(VGBD_PU);
public static final String sharedKey="pgpsympwd";



public static String getPassword(String username) {

    String selectStr = "select pgp_sym_decrypt(pgpsympassword, '" + sharedKey + "') from credentials where username='" + username + "'";

    EntityManager em =null;
    String password = "";

    try {
        em = emf.createEntityManager();

        java.util.Map<java.lang.String,java.lang.Object> propMap = em.getProperties();
        logger.info(propMap.keySet().size() + " properties");

        for (String key : propMap.keySet())
            logger.info(key + ", " + propMap.get(key));

        EntityTransaction tx = em.getTransaction(); ...

Answer 1

- , API :

public boolean isResourceLocal(EntityManager em) {

  try {
    EntityTransaction tx = em.getTransaction();
    return true;
  } catch (IllegalStateException ex) {
    return false;
  }

}

Answer 2

getTransaction() JTA, IllegalStateException.

. javadoc:

EntityTransaction getTransaction()

EntityTransaction . EntityTransaction .

: EntityTransaction

: IllegalStateException - JTA

EclipseLink :

public EntityTransaction getTransaction() {
    try {
        return ((TransactionWrapper)this.transaction).getTransaction();
    } catch (RuntimeException e) {
        setRollbackOnly();
        throw e;
    }
}