当Transactional遇上synchronized的解决方法分享

//controller层：
@GetMapping("/t1")
@Transactional(rollbackFor = Exception.class)
public void getTest1() {
    String n = countNumService.getCount();
    System.out.println(" t1 : " + n);
    try {
        Thread.sleep(60000);
    } catch (InterruptedException e) {
        throw new RuntimeException(e);
    }
}

@GetMapping("/t2")
@Transactional(rollbackFor = Exception.class)
public void getTest2() {
    String n = countNumService.getCount();
    System.out.println(" t2 : " + n);
    // 忽略其他的增删操作
}

//service层：
@Override
@Transactional(rollbackFor = Exception.class)
public synchronized String getCount() {
    // 获取
    CountNum countNum = countNumMapper.selectById(1);

    countNum.setNumber(countNum.getNumber() + 1);
    // 修改
    countNumMapper.updateById(countNum);

    return countNum.getNumber().toString();
}

@Override
@Transactional(rollbackFor = Exception.class)
public String getCount() {
    CountNum countNum = countNumMapper.selectById(1);
    // 使用版本号作为乐观锁
    int version = countNum.getVersion();
    countNum.setNumber(countNum.getNumber() + 1);
    countNum.setVersion(version + 1);
    // 更新操作必须要包含版本号字段
    int rows = countNumMapper.updateById(countNum);
    if (rows == 0) {
        throw new OptimisticLockException("事务中更新失败");
    }
    return countNum.getNumber().toString();
}

@Service
public class CountNumService {
    @Autowired
    private CountNumMapper countNumMapper;
    @Transactional(rollbackFor = Exception.class, propagation = Propagation.REQUIRED)
    public String getCount() {
         // 与之前代码相同
    }
}
@RestController
public class CountNumController {
    @Autowired
    private CountNumService countNumService;
    @GetMapping("/t1")
    public void getTest1() {
        String n = countNumService.getCount();
        System.out.println(" t1 : " + n);
        try {
            Thread.sleep(60000);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }
    @GetMapping("/t2")
    public void getTest2() {
        String n = countNumService.getCount();
        System.out.println(" t2 : " + n);
        // 忽略其他的增删操作
    }
}

@Mapper
public interface CountNumMapper {
    @Update("UPDATE count_num SET number = number + 1 WHERE id = 1")
    int updateNumber();
}
@Override
@Transactional(rollbackFor = Exception.class)
public String getCount() {
    // 直接执行 SQL 语句进行增量更新操作
    countNumMapper.updateNumber();
    // 再查询一次获取最新值
    CountNum countNum = countNumMapper.selectById(1);
    return countNum.getNumber().toString();
}

@Service
public class CountNumService {
    @Autowired
    private CountNumMapper countNumMapper;

    // 使用spring事务管理器
    @Autowired
    private PlatformTransactionManager transactionManager;

    public synchronized String getCount() {
        TransactionStatus status = null;
        try {
            DefaultTransactionDefinition definition = new DefaultTransactionDefinition();
            //将传播行为设置为 PROPAGATION_REQUIRED，以确保当前方法在事务内执行：
            definition.setPropagationBehavior(TransactionDefinition.PROPAGATION_REQUIRED);
            //获取当前事务的状态信息：
            status = transactionManager.getTransaction(definition);
            
            CountNum countNum = countNumMapper.selectById(1);
            countNum.setNumber(countNum.getNumber() + 1);

            int rows = countNumMapper.updateById(countNum);
            if (rows == 0) {
                throw new RuntimeException("事务中更新失败");
            }
            //提交事务：
            transactionManager.commit(status);
            return countNum.getNumber().toString();
        } catch (Exception e) {
            if (status != null) {
                //回滚事务：
                transactionManager.rollback(status);
            }
            throw e;
        }
    }
}