Transactions with Spring and Hibernate

This explains how to work with "User Transactions" when using the Spring base-class for Hibernate operations, HibernateDaoSupport.
The goal is to deal with transactions like this:

public void doSomething() {
    Transaction txn = null;
    try {
        txn = getTransaction();
        txn.begin();
        // do something here
        if (txn.isActive()) txn.commit();
    } catch (Exception e) {
        try {
            txn.rollback();
        } catch (Exception ignore) {}
        throw e;
    } finally {
        freeTransaction();
    }
}

The follwoing method returns a org.hibernate.Transaction object that contains the expected methods for transaction handling, like begin(), commit(), and rollback:

protected final Transaction getTransaction() {
    Session session = getSession();
    SessionFactory factory = getSessionFactory();
    if (TransactionSynchronizationManager.getResource(factory) == null) {
        TransactionSynchronizationManager.bindResource(factory,
                new SessionHolder(session));
    }
    return session.getTransaction();
}

When the transaction is no longer needed, its resources should be freed:

protected final void freeTransaction() {
    try {
        TransactionSynchronizationManager.unbindResource(getSessionFactory());
    } catch (Exception ignore) {}
    try {
        getSession().close();
    } catch (Exception ignore) {}
}