spring事务隔离级别 及其代码示例
时间: 2023-07-20 18:06:23 浏览: 106
Spring事务隔离级别默认是Isolation.DEFAULT,即采用数据库默认的事务隔离级别。但是Spring支持设置多种隔离级别,包括:
- Isolation.READ_UNCOMMITTED:读取未提交数据,具有最低的隔离级别,存在脏读、不可重复读和幻读的问题。
- Isolation.READ_COMMITTED:读取已提交数据,解决了脏读问题,但仍然存在不可重复读和幻读的问题。
- Isolation.REPEATABLE_READ:可重复读,解决了脏读和不可重复读问题,但仍然存在幻读问题。
- Isolation.SERIALIZABLE:串行化,隔离级别最高,避免了所有并发问题。
Spring使用@Transactional注解来设置事务隔离级别,示例如下:
@Service
@Transactional(isolation = Isolation.READ_COMMITTED)
public class UserServiceImpl implements UserService {
@Autowired
private UserDao userDao;
@Override
public void transfer(String fromUser, String toUser, int amount) throws Exception {
User from = userDao.findByName(fromUser);
User to = userDao.findByName(toUser);
if (from.getBalance() < amount) {
throw new RuntimeException("余额不足");
}
from.setBalance(from.getBalance() - amount);
to.setBalance(to.getBalance() + amount);
userDao.update(from);
userDao.update(to);
}
}
在上述代码中,@Transactional注解的isolation属性设置为Isolation.READ_COMMITTED,表示采用读取已提交数据的隔离级别。在transfer方法中,多个线程同时进行转账操作时,会采用该事务隔离级别来保证数据的一致性和正确性。
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