Foreword

More specific parameter introduction, and introduction of @Transactional failure scenarios, please click the link below to learn:

• @Transactional annotation parameters detailed explanation, as well as the use of annotation features (collector's edition)
• @TransactionalThe problem that annotations cause cross-database queries to fail

Body

I. Classification of exceptions

• Checked exceptions: exceptions other than RuntimeException under Exception;
• Unchecked exceptions: RuntimeException and its subclasses and Errors;

Second, @Transactional attribute introduction

There are roughly nine key attributes of the @Transactional annotation (as shown in the figure):

Three, @Transactional use

When using the @Transaction annotation, the Alibaba Code Specification plugin will remind you to specify rollbackFor to display the rollback.

By default, the Spring framework only throws runtime exceptions (checked exceptions - checked exceptions) and unchecked exceptions (unchecked exceptions) when using @Transaction to handle transactions by default. the transaction is rolled back.That is, when an instance of RuntimeException or its subclasses is thrown, Checked exceptions thrown from transaction methods will not be flagged for transaction rollback.

• To rollback the checked exception: add @Transactional(rollbackOn=Exception.class)
before the entire method
• Make unchecked exception not rollback: @Transactional(dontRollbackOn=RunTimeException.class)
• Methods that do not require transaction management (query only): @Transactional(propagation=Propagation.NOT_SUPPORTED)

Note:

• If the exception is try-catch, the transaction will not be rolled back. If you want the transaction to be rolled back, you must throw try{}catch{throw Exception}.
• The Spring team's recommendation is to use the @Transactional annotation on concrete classes (or class methods), not on any interfaces that the class implements.You can also use the @Transactional annotation on the interface, but this will only take effect when you need to set an interface-based proxy
• The method identified by the @Transactional annotation, it is recommended that the processing process be as simple as possible.Especially the transaction method with lock, it is best not to put it in the transaction if it can not be placed in the transaction.Regular database query operations can be carried out in front of the transaction, and operations such as addition, deletion, and modification can be placed in the transaction

Four. Test

If the code in the catch block is not written, the transaction will not be rolled back.Because the transaction is caught by catch, the transaction can only be rolled back manually.

@[email protected] class DemoService {@Autowiredprivate DemoMapper demoMapper;@Transactionalpublic Integer insert(MemberEntity memberEntity) {Integer insertResult = 0;try {insertResult = demoMapper.save(memberEntity);log.info("insertResult:{}", insertResult);int result = 1 / memberEntity.getAge();} catch (Exception e) {log.error("errorMsg:{}", e.getMessage());// catch exception, must roll back manuallyTransactionAspectSupport.currentTransactionStatus().setRollbackOnly();}return insertResult;}}