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java 如何锁定库存

2026-03-23 23:41:59Java

锁定库存的实现方法

在Java中锁定库存通常涉及数据库操作和并发控制，以下是几种常见实现方式：

使用数据库事务和悲观锁

通过SELECT FOR UPDATE语句在查询时直接锁定记录：

@Transactional
public boolean lockStock(Long productId, Integer quantity) {
    // 查询并锁定库存记录
    Stock stock = entityManager.createQuery(
        "SELECT s FROM Stock s WHERE s.productId = :pid FOR UPDATE", 
        Stock.class)
        .setParameter("pid", productId)
        .getSingleResult();

    if (stock.getAvailable() >= quantity) {
        stock.setLocked(stock.getLocked() + quantity);
        stock.setAvailable(stock.getAvailable() - quantity);
        entityManager.persist(stock);
        return true;
    }
    return false;
}

使用乐观锁机制

通过版本号控制实现乐观锁：

@Entity
public class Stock {
    @Id
    private Long productId;
    private Integer available;
    private Integer locked;

    @Version
    private Long version; // 乐观锁版本字段
}

@Transactional
public boolean lockStock(Long productId, Integer quantity) {
    Stock stock = stockRepository.findById(productId).orElseThrow();
    if (stock.getAvailable() >= quantity) {
        stock.setLocked(stock.getLocked() + quantity);
        stock.setAvailable(stock.getAvailable() - quantity);
        stockRepository.save(stock);
        return true;
    }
    return false;
}

分布式锁实现

使用Redis实现分布式锁：

public boolean lockStockWithRedis(Long productId, Integer quantity) {
    String lockKey = "stock_lock:" + productId;
    String clientId = UUID.randomUUID().toString();

    try {
        // 尝试获取锁
        Boolean locked = redisTemplate.opsForValue().setIfAbsent(
            lockKey, clientId, 30, TimeUnit.SECONDS);

        if (Boolean.TRUE.equals(locked)) {
            Stock stock = stockRepository.findById(productId).orElseThrow();
            if (stock.getAvailable() >= quantity) {
                stock.setLocked(stock.getLocked() + quantity);
                stock.setAvailable(stock.getAvailable() - quantity);
                stockRepository.save(stock);
                return true;
            }
        }
        return false;
    } finally {
        // 释放锁
        if (clientId.equals(redisTemplate.opsForValue().get(lockKey))) {
            redisTemplate.delete(lockKey);
        }
    }
}

库存预占表设计

创建单独的预占记录表：

java 如何锁定库存

@Entity
public class StockReservation {
    @Id
    @GeneratedValue
    private Long id;
    private Long productId;
    private Integer quantity;
    private String orderId;
    private LocalDateTime expireTime;
    private Integer status; // 0-预占中 1-已确认 2-已释放
}