Question

鉴于这些实体和存储库在DDBB中访问其数据：

@Entity
public class Customer {
Long id;
}

@Entity
public class Purchase {
    Long customerId;
}

@Repository
public lass PurchaseDAO {

   public void insert(Purchase insert);

   public void deleteCustomerPurchases(Long customerId);

   public long getTotalPurchasesAmount(Long customerId);

   public long getTotalPurchasesAmountPerMonth(Long customerId, int month);
}

我想为方法getTotalPurchaseAmounts（Long customerId）添加缓存，这样，当为客户添加一些购买时，只有被购买的客户被驱逐。

相关配置：

@EnableCaching
@Configuration
public class CommonConfig {

    @Bean
    public CacheManager cacheManager() {
        EhCacheCacheManager cacheManager = new EhCacheCacheManager();
        cacheManager.setCacheManager( ehCacheManager().getObject() );
        return cacheManager;
    }

    @Bean
    public EhCacheManagerFactoryBean ehCacheManager() {
        EhCacheManagerFactoryBean ehcache = new EhCacheManagerFactoryBean();
        ehcache.setConfigLocation( new ClassPathResource( "ehcache.xml" ) );
        return ehcache;
    }

}

由于弹簧缓存（和ehcache）逐出被限制为元素或所有条目，我开发的解决方案是创建缓存（每个客户一个），所以我可以逐出。

我认为最好的扩展点是实现自定义CacheResolver：

@Component("CustomerPurchasesCacheResolver")
public class CustomerPurchasesCacheResolver implements CacheResolver {

    @Autowired
    private EhCacheCacheManager cacheManager;

    @Override
    public Collection<? extends Cache> resolveCaches( CacheOperationInvocationContext<?> context ) {
        String cacheName = "customerPurchases_" + getCustomerId( context );
        // Add cache to cacheManager if it does not exists
        cacheManager.getCacheManager().addCacheIfAbsent( cacheName );

        Set<Cache> caches = new HashSet<>();
        caches.add( cacheManager.getCache( cacheName ) );
        return caches;
    }

    // Retrieves customerId from cache operation invocation context;
    private Long getCustomerId( CacheOperationInvocationContext<?> context ) {
    String key = ( (CacheOperation) context.getOperation() ).getKey();
        // TODO Evaluate key
        // HOW CAN I DO THIS????????????
        return null;
    }

}

并将Spring缓存添加到我的存储库方法中：

@Repository
public lass PurchaseDAO {

   @CacheEvict(cacheResolver="CustomerPurchasesCacheResolver", key="#purchase.customerId")       
   public void insert(Purchase purchase);

   @CacheEvict(cacheResolver="CustomerPurchasesCacheResolver", key="#customerId")       
   public void deleteCustomerPurchases(Long customerId);

   @Cacheable(cacheResolver="CustomerPurchasesCacheResolver")
   public long getTotalPurchasesAmount(Long customerId);

   @Cacheable(cacheResolver="CustomerPurchasesCacheResolver")
   public long getTotalPurchasesAmountPerMonth(Long customerId, int month);

}

我使用这个方法的唯一问题是使用Spring Expresions来评估密钥。

有没有办法让这个或不同的方法有效？

Answer 1

为每个客户记录创建缓存太过分了。使用SpEL，您可以指定要逐出的客户记录的密钥。配置ehcache以便有一个客户缓存。然后，您更改PurchaseDAO方法，以便它们指定要缓存或逐出的密钥。更改您的代码如下

find / -type l -name 'ctags-exuberant' 2>/dev/null

但是，要回答有关从CacheResolver获取customerId的问题，CacheOperationInvocationContext有一个getArgs（）方法，该方法返回传递给要缓存的方法的参数。

@CacheEvict(value = "customerCache" , key="#purchase.customerId")       
public void insert(Purchase purchase);

@Cacheable( value = "customerCache" ,key = "#customerId") // you can omit the key if using default key generator as it still uses the method argument
public long getTotalPurchasesAmount(Long customerId);

是否有可能驱逐弹簧缓存部分数据？

1 个答案: