springboot中如何实现数据库锁机制

Question

我想插入一条不存在的记录，两条记录都保存而不是一条记录，如果并发请求的时间相同，则只保存一条记录。

@GetMapping("/bookslot")
    public void bookTicket() {
        ExecutorService executor = Executors.newFixedThreadPool(2);
        executor.execute(run(slotService::method1));
        executor.execute(run(slotService::method2));
        executor.shutdown();
    }

    private Runnable run(FailableRunnable<Exception> runnable) {
        return () -> {
            try {
                runnable.run();
            } catch (Exception e) {
                e.printStackTrace();
            }
};
    }

存储库

@Lock(LockModeType.PESSIMISTIC_WRITE)
    @Query("SELECT e FROM Slot e WHERE e.time = :time")
    Optional<Slot> findByTimeWithLock(@Param("time") LocalTime time);

服务等级

@Transactional
    public void method1() throws InterruptedException {
        saveSlot("sam", "07:00");
        Thread.sleep(1000); 
    }

    @Transactional
    public void method2() throws InterruptedException {
        saveSlot("Curran", "07:00");
        Thread.sleep(1000); 
    }

@Transactional
    public void saveSlot(String name, String newTime) {
        LocalTime time = LocalTime.parse(newTime);     
        Optional<Slot> slotOptional = slotRepo.findByTimeWithLock(time);
       
        if (!slotOptional.isPresent()) {
            Slot newSlot = new Slot();
            newSlot.setName(name);
            newSlot.setTime(time);
            slotRepo.save(newSlot);
        }
    }

Answer 1

仅当您想使用JVM 范围内的设计模式。