编辑“︁Spring缓存同步”︁（章节）

== 实际案例 ==  
=== 电商库存同步 ===  
在高并发下单场景中，使用`@Cacheable`同步防止超卖：  
<syntaxhighlight lang="java">  
@Cacheable(value = "inventory", key = "#productId", sync = true)  
public Integer getStock(String productId) {  
    return inventoryService.getStock(productId);  
}  

@CacheEvict(value = "inventory", key = "#productId")  
public void deductStock(String productId, int quantity) {  
    inventoryService.deduct(productId, quantity);  
}  
</syntaxhighlight>  

=== 流程图解 ===  
<mermaid>  
sequenceDiagram  
    participant Client1  
    participant Client2  
    participant Cache  
    participant DB  
    Client1->>Cache: getStock(101) (首次请求)  
    Cache->>DB: 查询库存  
    DB-->>Cache: 库存=100  
    Cache-->>Client1: 100  
    Client2->>Cache: getStock(101) (并发请求)  
    Cache->>Client2: 等待同步锁  
    Client1->>Cache: deductStock(101,1)  
    Cache->>DB: 扣减库存  
    DB-->>Cache: 成功  
    Cache-->>Client1: OK  
    Cache-->>Client2: 99 (返回更新后结果)  
</mermaid>