Spring declarative versus annotation

Question

I am new to Spring 3 and it offers a bunch of annotations, which avoids the declarative approach. What exactly is the difference between annotation based and declarative approach? Are there any downsides to annotation based?

Answer 1

Using annotations is one way to use a declarative approach, as opposed to using a programmpatic approach, involving additional Java code in your methods:

Declarative approach:

@Transactional
public void transferMoney(Long debitorId, Long creditorId, BigDecimal amount) {
    Account debitor = accountDAO.findById(debitorId);
    Account creditor = accountDAO.findById(creditorId);
    creditor.add(amount);
    debitor.remove(amount);
}

Programmatic approach:

public void transferMoney(Long debitorId, Long creditorId, BigDecimal amount) {
    transactionTemplate.execute(new TransactionCallbackWithoutResult() {
        @Override
        protected void doInTransactionWithoutResult(TransactionStatus status) {
            Account debitor = accountDAO.findById(debitorId);
            Account creditor = accountDAO.findById(creditorId);
            creditor.add(amount);
            debitor.remove(amount);
        }
    });
}