What is the purpose of the @Transactional annotation in Spring?

The @Transactional annotation in Spring is used to specify that a method or class should be managed by a transaction manager. A transaction is a series of operations that either all successfully execute or all fail and roll back. The @Transactional annotation can be applied at the method level or class level.

When the @Transactional annotation is applied to a method, the method will be wrapped in a transaction. If the method execution is successful, the transaction will be committed, and if an exception occurs during method execution, the transaction will be rolled back.

When the @Transactional annotation is applied at the class level, all public methods in that class will be wrapped in a transaction.

By using the @Transactional annotation, transaction management code can be simplified and a more flexible way of controlling transactions is provided. For example, different transaction propagation behaviors can be set to control the transaction relationship between methods, as well as setting transaction isolation levels and timeout times.

In conclusion, the @Transactional annotation is one of the core annotations in Spring for transaction management, used to declare that a method or class needs to be managed by a transaction manager and provides a series of properties to control the behavior of the transaction.