Does it set a flag in a bean ? Does it load "special" bean which then looks for <code>@Transactional</code> ?

It scans all beans in the application context and creates AOP interceptor for those which are annotated. This is done via the <code>SpringTransactionAnnotationParser</code>, which is used by <code>TransactionInterceptor</code> - the aformentioned interceptor. Then whenever these beans are accessed, this advice is triggered and a transaction is started before the target method is executed, and committed after the execution.

What does <tx:annotation-driven/> in Spring really do in the code level?

1 Answers

It scans all beans in the application context and creates AOP interceptor for those which are annotated.

This is done via the SpringTransactionAnnotationParser, which is used by TransactionInterceptor - the aformentioned interceptor.

Then whenever these beans are accessed, this advice is triggered and a transaction is started before the target method is executed, and committed after the execution.