Spring中事务你用对了吗
背景
Spring中为JTA，JPA，Hibernate等事务API提供了一致性的编程模型，但是编程式事务需要编码支持，在实际中很少使用。所以Spring提供了声明式事务，
配合SpringBoot，我们可以通过@Transactional注解，轻松地实现事务的控制，让事务控制达到极简。注解事务固然方便，但是如果对它不够了解，很容易
留下坑，就我目前的项目中，有一些事务根本就没有生效。
开始
新建工程
引入H2 Database
spring.datasource.url=jdbc:h2:mem:testdb;DB_CLOSE_ON_EXIT=FALSE
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=root
spring.datasource.password=root
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.jpa.properties.show_sql=true
spring.jpa.properties.format_sql=true
spring.jpa.properties.use_sql_comments=true
spring.h2.console.enabled=true
spring.h2.console.path=/console
logging.level.org.springframework.orm.jpa=debug
都是一些基础的配置，这里使用了jpa，并且把日志级别设置成debug，为了更方便的观察事务的执行情况。
编写一个业务类
@Service
public class DataService {
@Autowired
private UserRepository userRepository;
private final Logger logger = LoggerFactory.getLogger(DataService.class);
@Transactional(rollbackFor = RuntimeException.class)
public void saveA(String user) {
logger.info("invoke saveA {}", user);
User u = new User();
u.setName(user);
userRepository.save(u);
}
public void saveB(String user) {
logger.info("invoke saveB {}", user);
try {
User u = new User();
u.setName(user);
this.saveAndRollback(user);
} catch (RuntimeException e) {
logger.warn("catch an exception in saveB()");
}
}
public void findAll() {
logger.info("print data:");
userRepository.findAll().forEach(user -> logger.info(user.toString()));
}
@Transactional(rollbackFor = RuntimeException.class)
public void saveAndRollback(String user) {
logger.info("invoke saveAndRollback {}", user);
User u = new User();
u.setName(user);
userRepository.save(u);
throw new RuntimeException();
}
}
验证栗子
@SpringBootApplication
@EnableTransactionManagement
public class Application implements ApplicationRunner {
@Autowired
private DataService dataService;
private final Logger logger = LoggerFactory.getLogger(Application.class);
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
@Override
public void run(ApplicationArguments args) throws Exception {
demo1();
}
private void demo1() {
dataService.saveA("frank");//1
dataService.findAll();
try {
dataService.saveAndRollback("frank");//2
} catch (Exception e) {
logger.warn("catch an save exception");
}
dataService.findAll();
dataService.saveB("jack");//3
dataService.findAll();
}
}
代码1执行结果，上面是insert，下面是查询操作
2020-03-31 14:14:14.733 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Creating new transaction with name [org.boot.transaction.service.DataService.saveA]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT,-java.lang.RuntimeException
2020-03-31 14:14:14.733 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Opened new EntityManager [SessionImpl(1955991197<open>)] for JPA transaction
2020-03-31 14:14:14.740 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Exposing JPA transaction as JDBC [org.springframework.orm.jpa.vendor.HibernateJpaDialect$HibernateConnectionHandle@4e4162bc]
2020-03-31 14:14:14.754 INFO 17477 --- [ main] o.boot.transaction.service.DataService : invoke saveA frank
2020-03-31 14:14:14.758 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Found thread-bound EntityManager [SessionImpl(1955991197<open>)] for JPA transaction
2020-03-31 14:14:14.759 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Participating in existing transaction
2020-03-31 14:14:14.804 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Initiating transaction commit
2020-03-31 14:14:14.805 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Committing JPA transaction on EntityManager [SessionImpl(1955991197<open>)]
2020-03-31 14:14:14.822 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Closing JPA EntityManager [SessionImpl(1955991197<open>)] after transaction
print data:
2020-03-31 14:14:14.823 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Creating new transaction with name [org.springframework.data.jpa.repository.support.SimpleJpaRepository.findAll]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT,readOnly
2020-03-31 14:14:14.824 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Opened new EntityManager [SessionImpl(2045560071<open>)] for JPA transaction
2020-03-31 14:14:14.841 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Exposing JPA transaction as JDBC [org.springframework.orm.jpa.vendor.HibernateJpaDialect$HibernateConnectionHandle@7e5efcab]
2020-03-31 14:14:15.059 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Initiating transaction commit
2020-03-31 14:14:15.060 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Committing JPA transaction on EntityManager [SessionImpl(2045560071<open>)]
2020-03-31 14:14:15.060 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Closing JPA EntityManager [SessionImpl(2045560071<open>)] after transaction
2020-03-31 14:14:15.061 INFO 17477 --- [ main] o.boot.transaction.service.DataService : User{id=1, name='frank'}
这里可以看到插入成功了
代码2执行结果
2020-03-31 14:14:15.062 INFO 17477 --- [ main] o.boot.transaction.service.DataService : invoke saveAndRollback frank
2020-03-31 14:14:15.062 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Found thread-bound EntityManager [SessionImpl(1796154990<open>)] for JPA transaction
2020-03-31 14:14:15.062 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Participating in existing transaction
2020-03-31 14:14:15.063 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Initiating transaction rollback
2020-03-31 14:14:15.063 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Rolling back JPA transaction on EntityManager [SessionImpl(1796154990<open>)]
2020-03-31 14:14:15.067 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Closing JPA EntityManager [SessionImpl(1796154990<open>)] after transaction
2020-03-31 14:14:15.068 WARN 17477 --- [ main] org.boot.transaction.Application : catch an save exception
2020-03-31 14:14:15.068 INFO 17477 --- [ main] o.boot.transaction.service.DataService : print data:
2020-03-31 14:14:15.068 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Creating new transaction with name [org.springframework.data.jpa.repository.support.SimpleJpaRepository.findAll]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT,readOnly
2020-03-31 14:14:15.069 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Opened new EntityManager [SessionImpl(1138190994<open>)] for JPA transaction
2020-03-31 14:14:15.069 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Exposing JPA transaction as JDBC [org.springframework.orm.jpa.vendor.HibernateJpaDialect$HibernateConnectionHandle@4a2bf50f]
2020-03-31 14:14:15.076 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Initiating transaction commit
2020-03-31 14:14:15.076 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Committing JPA transaction on EntityManager [SessionImpl(1138190994<open>)]
2020-03-31 14:14:15.076 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Closing JPA EntityManager [SessionImpl(1138190994<open>)] after transaction
2020-03-31 14:14:15.076 INFO 17477 --- [ main] o.boot.transaction.service.DataService : User{id=1, name='frank'}
从这里的结果可以看出，这时候数据没有插入，还是我们第一次添加的数据，说明事务生效了。
代码3执行结果
2020-03-31 14:14:15.076 INFO 17477 --- [ main] o.boot.transaction.service.DataService : invoke saveB jack
2020-03-31 14:14:15.076 INFO 17477 --- [ main] o.boot.transaction.service.DataService : invoke saveAndRollback jack
2020-03-31 14:14:15.077 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Creating new transaction with name [org.springframework.data.jpa.repository.support.SimpleJpaRepository.save]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT
2020-03-31 14:14:15.077 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Opened new EntityManager [SessionImpl(1683617002<open>)] for JPA transaction
2020-03-31 14:14:15.077 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Exposing JPA transaction as JDBC [org.springframework.orm.jpa.vendor.HibernateJpaDialect$HibernateConnectionHandle@740b9a50]
2020-03-31 14:14:15.077 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Initiating transaction commit
2020-03-31 14:14:15.077 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Committing JPA transaction on EntityManager [SessionImpl(1683617002<open>)]
2020-03-31 14:14:15.078 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Closing JPA EntityManager [SessionImpl(1683617002<open>)] after transaction
2020-03-31 14:14:15.078 WARN 17477 --- [ main] o.boot.transaction.service.DataService : catch an exception in saveB()
2020-03-31 14:14:15.078 INFO 17477 --- [ main] o.boot.transaction.service.DataService : print data:
2020-03-31 14:14:15.078 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Creating new transaction with name [org.springframework.data.jpa.repository.support.SimpleJpaRepository.findAll]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT,readOnly
2020-03-31 14:14:15.079 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Opened new EntityManager [SessionImpl(589094312<open>)] for JPA transaction
2020-03-31 14:14:15.079 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Exposing JPA transaction as JDBC [org.springframework.orm.jpa.vendor.HibernateJpaDialect$HibernateConnectionHandle@6b70d1fb]
2020-03-31 14:14:15.080 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Initiating transaction commit
2020-03-31 14:14:15.080 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Committing JPA transaction on EntityManager [SessionImpl(589094312<open>)]
2020-03-31 14:14:15.081 DEBUG 17477 --- [ main] o.s.orm.jpa.JpaTransactionManager : Closing JPA EntityManager [SessionImpl(589094312<open>)] after transaction
2020-03-31 14:14:15.081 INFO 17477 --- [ main] o.boot.transaction.service.DataService : User{id=1, name='frank'}
2020-03-31 14:14:15.081 INFO 17477 --- [ main] o.boot.transaction.service.DataService : User{id=3, name='jack'}
这里看到最后的查询结果有两条数据，说明这里虽然产生了异常，但是数据没有回滚，说明事务没有生效。
分析原因
从代码层面上看，代码2和代码3的区别是：代码2是直接调用的带@Transactional注解的方法（saveAndRollback），而代码3调用的方法（saveB）没有@Transactional注解，在saveB中调用了saveAndRollback方法，这属于内部调用，也就是通过this去调用对象的方法。而Spring的事务是通过AOP实现的，AOP会在加了事务注解的方法上进行增强，而Spring实现AOP主要是通过动态代理的方式，所以Spring做事务增强是在代理类上面做的增强，而我们用this去调用原来的方法，是没有做增强的，所以事务也就不会生效。
解决方法也很简单，只有被AOP增强过的类事务才会生效，有三种：
- 注入DataService本身调用
- 通过ApplicationContext拿到bean之后调用
- 使用AopContext获取到代理类调用
所以我们在DataService中增加如下方法：
@Transactional(rollbackFor = RuntimeException.class)
public void saveAndRollback(String user) {
logger.info("invoke saveAndRollback {}", user);
User u = new User();
u.setName(user);
userRepository.save(u);
throw new RuntimeException();
}
public void invokeSelf(String user) {
try {
dataService.saveAndRollback(user);
} catch (RuntimeException e) {
logger.warn("catch an exception in invokeSelf()");
}
}
public void invokeWithApplicationContext(String user) {
try {
((DataService) applicationContext.getBean("dataService")).saveAndRollback(user);
} catch (RuntimeException e) {
logger.warn("catch an exception in invokeWithApplicationContext()");
}
}
public void invokeWithAop(String user) {
try {
// 需要把@EnableAspectJAutoProxy注解中的(exposeProxy = true)
((DataService) AopContext.currentProxy()).saveAndRollback(user);
} catch (RuntimeException e) {
logger.warn("catch an exception in invokeWithAop()");
}
}
再来运行看看结果
dataService.saveA("frank");
dataService.invokeSelf("frank");
dataService.findAll();
dataService.invokeWithApplicationContext("tom");
dataService.findAll();
dataService.invokeWithAop("jack");
dataService.findAll();
可以看到日志中，出现异常的地方出现了rollback字样，说明事务都生效了
2020-03-31 18:02:09.622 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Opened new EntityManager [SessionImpl(1779787990<open>)] for JPA transaction
2020-03-31 18:02:09.645 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Exposing JPA transaction as JDBC [org.springframework.orm.jpa.vendor.HibernateJpaDialect$HibernateConnectionHandle@411fa0ce]
2020-03-31 18:02:10.011 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Initiating transaction commit
2020-03-31 18:02:10.012 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Committing JPA transaction on EntityManager [SessionImpl(1779787990<open>)]
2020-03-31 18:02:10.012 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Closing JPA EntityManager [SessionImpl(1779787990<open>)] after transaction
2020-03-31 18:02:10.013 INFO 20635 --- [ main] o.boot.transaction.service.DataService : User{id=1, name='frank'}
2020-03-31 18:02:10.013 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Creating new transaction with name [org.boot.transaction.service.DataService.saveAndRollback]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT,-java.lang.RuntimeException
2020-03-31 18:02:10.013 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Opened new EntityManager [SessionImpl(1478269879<open>)] for JPA transaction
2020-03-31 18:02:10.013 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Exposing JPA transaction as JDBC [org.springframework.orm.jpa.vendor.HibernateJpaDialect$HibernateConnectionHandle@138f0661]
2020-03-31 18:02:10.014 INFO 20635 --- [ main] o.boot.transaction.service.DataService : invoke saveAndRollback tom
2020-03-31 18:02:10.014 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Found thread-bound EntityManager [SessionImpl(1478269879<open>)] for JPA transaction
2020-03-31 18:02:10.014 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Participating in existing transaction
2020-03-31 18:02:10.015 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Initiating transaction rollback
2020-03-31 18:02:10.016 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Rolling back JPA transaction on EntityManager [SessionImpl(1478269879<open>)]
2020-03-31 18:02:10.018 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Closing JPA EntityManager [SessionImpl(1478269879<open>)] after transaction
2020-03-31 18:02:10.018 WARN 20635 --- [ main] o.boot.transaction.service.DataService : catch an exception in invokeWithApplicationContext()
2020-03-31 18:02:10.018 INFO 20635 --- [ main] o.boot.transaction.service.DataService : print data:
2020-03-31 18:02:10.018 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Creating new transaction with name [org.springframework.data.jpa.repository.support.SimpleJpaRepository.findAll]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT,readOnly
2020-03-31 18:02:10.019 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Opened new EntityManager [SessionImpl(321795476<open>)] for JPA transaction
2020-03-31 18:02:10.019 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Exposing JPA transaction as JDBC [org.springframework.orm.jpa.vendor.HibernateJpaDialect$HibernateConnectionHandle@4f235107]
2020-03-31 18:02:10.020 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Initiating transaction commit
2020-03-31 18:02:10.020 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Committing JPA transaction on EntityManager [SessionImpl(321795476<open>)]
2020-03-31 18:02:10.020 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Closing JPA EntityManager [SessionImpl(321795476<open>)] after transaction
2020-03-31 18:02:10.020 INFO 20635 --- [ main] o.boot.transaction.service.DataService : User{id=1, name='frank'}
2020-03-31 18:02:10.020 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Creating new transaction with name [org.boot.transaction.service.DataService.saveAndRollback]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT,-java.lang.RuntimeException
2020-03-31 18:02:10.020 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Opened new EntityManager [SessionImpl(977952572<open>)] for JPA transaction
2020-03-31 18:02:10.021 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Exposing JPA transaction as JDBC [org.springframework.orm.jpa.vendor.HibernateJpaDialect$HibernateConnectionHandle@4f3356c0]
2020-03-31 18:02:10.021 INFO 20635 --- [ main] o.boot.transaction.service.DataService : invoke saveAndRollback jack
2020-03-31 18:02:10.021 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Found thread-bound EntityManager [SessionImpl(977952572<open>)] for JPA transaction
2020-03-31 18:02:10.021 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Participating in existing transaction
2020-03-31 18:02:10.022 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Initiating transaction rollback
2020-03-31 18:02:10.022 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Rolling back JPA transaction on EntityManager [SessionImpl(977952572<open>)]
2020-03-31 18:02:10.023 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Closing JPA EntityManager [SessionImpl(977952572<open>)] after transaction
2020-03-31 18:02:10.023 WARN 20635 --- [ main] o.boot.transaction.service.DataService : catch an exception in invokeWithAop()
2020-03-31 18:02:10.023 INFO 20635 --- [ main] o.boot.transaction.service.DataService : print data:
2020-03-31 18:02:10.023 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Creating new transaction with name [org.springframework.data.jpa.repository.support.SimpleJpaRepository.findAll]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT,readOnly
2020-03-31 18:02:10.023 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Opened new EntityManager [SessionImpl(1367900185<open>)] for JPA transaction
2020-03-31 18:02:10.023 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Exposing JPA transaction as JDBC [org.springframework.orm.jpa.vendor.HibernateJpaDialect$HibernateConnectionHandle@6f50d55c]
2020-03-31 18:02:10.024 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Initiating transaction commit
2020-03-31 18:02:10.024 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Committing JPA transaction on EntityManager [SessionImpl(1367900185<open>)]
2020-03-31 18:02:10.025 DEBUG 20635 --- [ main] o.s.orm.jpa.JpaTransactionManager : Closing JPA EntityManager [SessionImpl(1367900185<open>)] after transaction
2020-03-31 18:02:10.025 INFO 20635 --- [ main] o.boot.transaction.service.DataService : User{id=1, name='frank'}
小结
在 Spring 的 AOP 代理下，只有目标方法由外部调用，目标方法才由 Spring 生成的代理对象来管理，这会造成自调用问题。若同一类中的其他没有@Transactional 注解的方法内部调用有@Transactional 注解的方法，有@Transactional 注解的方法的事务被忽略，不会发生回滚。解决方法上面已经列出，并且放在了github上。所以平时在内部调用带有事务的方法时，要小心一点。
还有以下常见场景事务也会失效
- @Transactional注解到非public方法上
- 如果在事务中抛出了未检查异常（继承自 RuntimeException的异常，也就是说如果有IO操作，抛出了IOException，事务是不会回滚的）或者Error，则 Spring 将回滚事务；除此之外，Spring 不会回滚事务。注意，这里说的是需要抛出，如果没有抛出，比如异常被catch吞了，事务是不会回滚的。
