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

Does it set a flag in a bean ? Does it load "special" bean 开发者_开发百科which then looks for @Transactional ?

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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.