Spring4.1新特性——Spring缓存框架增强

Spring 4.1提供了对jcache的支持，并对cache抽象部分进行了一些简单的增强。在集成jcache时是非常费劲的，版本之间各种不兼容，不建议用于正式环境，在正式环境中可以使用如Guava Cache或Ehcache。

 

jcache依赖：

<dependency>
    <groupId>net.sf.ehcache</groupId>
    <artifactId>ehcache-jcache</artifactId>
    <version>${ehcache-jcache.version}</version>
</dependency>
<dependency>
    <groupId>javax.cache</groupId>
    <artifactId>cache-api</artifactId>
    <version>${javax.cache.version}</version>
</dependency>
<dependency>
    <groupId>org.jsr107.ri</groupId>
    <artifactId>cache-ri-impl</artifactId>
    <version>${cache-ri-impl.version}</version>
</dependency>

<javax.cache.version>1.0.0</javax.cache.version>、<cache-ri-impl.version>1.0.0</cache-ri-impl.version>、<ehcache-jcache.version>1.2</ehcache-jcache.version>，具体请参考源码。

 

1、Jcache集成

创建Cache： 

javax.cache.CacheManager cacheManager = Caching.getCachingProvider().getCacheManager();
MutableConfiguration<Object, Object> mutableConfiguration = new MutableConfiguration<Object, Object>();
mutableConfiguration.setStoreByValue(false);  // otherwise value has to be Serializable
cacheManager.createCache("user", mutableConfiguration);
cacheManager.createCache("user2", mutableConfiguration);
cacheManager.createCache("user3", mutableConfiguration);

JCacheCacheManager jCacheCacheManager = new JCacheCacheManager(cacheManager);
return jCacheCacheManager;

 

Java Config方式提供了CachingConfigurer用于提供配置回调：   

@Configuration
@ComponentScan(basePackages = "com.sishuok.spring.service")
@EnableCaching(proxyTargetClass = true)
public class AppConfig implements CachingConfigurer {
    @Bean
    @Override
    public CacheManager cacheManager() {
        javax.cache.CacheManager cacheManager = Caching.getCachingProvider().getCacheManager();
        MutableConfiguration<Object, Object> mutableConfiguration = new MutableConfiguration<Object, Object>();
        mutableConfiguration.setStoreByValue(false);  // otherwise value has to be Serializable
        cacheManager.createCache("user", mutableConfiguration);
        cacheManager.createCache("user2", mutableConfiguration);
        cacheManager.createCache("user3", mutableConfiguration);

        JCacheCacheManager jCacheCacheManager = new JCacheCacheManager(cacheManager);
        return jCacheCacheManager;
    }

    @Bean
    @Override
    public CacheResolver cacheResolver() {
        return new MyCacheResolver();
    }

    @Bean
    @Override
    public KeyGenerator keyGenerator() {
        return new SimpleKeyGenerator();
    }

    @Override
    public CacheErrorHandler errorHandler() {
        return new CacheErrorHandler() {
            @Override
            public void handleCacheGetError(RuntimeException exception, Cache cache, Object key) {
                System.out.println("cache get error");
            }

            @Override
            public void handleCachePutError(RuntimeException exception, Cache cache, Object key, Object value) {
                System.out.println("cache put error");
            }

            @Override
            public void handleCacheEvictError(RuntimeException exception, Cache cache, Object key) {
                System.out.println("cache evict error");
            }

            @Override
            public void handleCacheClearError(RuntimeException exception, Cache cache) {
                System.out.println("cache clear error");
            }
        };
    }
}

 

 

2、@CacheConfig指定全局Cache配置

Spring 4.1之前需要每个方法上都指定： 

@Service
public class UserService {

    Set<User> users = new HashSet<User>();

    @CachePut(value = "user", key = "#user.id")
    public User save(User user) {
        users.add(user);
        return user;
    }

    @CachePut(value = "user", key = "#user.id")
    public User update(User user) {
        users.remove(user);
        users.add(user);
        return user;
    }

    @CacheEvict(value = "user", key = "#user.id")
    public User delete(User user) {
        users.remove(user);
        return user;
    }

    @CacheEvict(value = "user", allEntries = true)
    public void deleteAll() {
        users.clear();
    }

    @Cacheable(value = "user", key = "#id")
    public User findById(final Long id) {
        System.out.println("cache miss, invoke find by id, id:" + id);
        for (User user : users) {
            if (user.getId().equals(id)) {
                return user;
            }
        }
        return null;
    }

}

 

 

Spring 4.1时可以直接在类级别使用@CacheConfig指定： 

@Service
@CacheConfig(cacheNames = {"user", "user2"})
public class UserService {

    Set<User> users = new HashSet<User>();

    @CachePut(key = "#user.id")
    public User save(User user) {
        users.add(user);
        return user;
    }

    @CachePut(key = "#user.id")
    public User update(User user) {
        users.remove(user);
        users.add(user);
        return user;
    }

    @CacheEvict(key = "#user.id")
    public User delete(User user) {
        users.remove(user);
        return user;
    }

    @CacheEvict(allEntries = true)
    public void deleteAll() {
        users.clear();
    }

    @Cacheable(key = "#id")
    public User findById(final Long id) {
        System.out.println("cache miss, invoke find by id, id:" + id);
        for (User user : users) {
            if (user.getId().equals(id)) {
                return user;
            }
        }
        return null;
    }
}

 

3、CacheResolver

其名字已经暗示了其是Cache解析器，用于根据实际情况来动态解析使用哪个Cache，如： 

public class MyCacheResolver implements CacheResolver {

    @Autowired
    private CacheManager cacheManager;

    @Override
    public Collection<? extends Cache> resolveCaches(CacheOperationInvocationContext<?> context) {
        List<Cache> caches = new ArrayList<Cache>();
        for(String cacheName : context.getOperation().getCacheNames()) {
            caches.add(cacheManager.getCache(cacheName));
        }
        if(context.getTarget() instanceof UserService2) {
            caches.add(cacheManager.getCache("user2"));
            caches.add(cacheManager.getCache("user3"));
        }
        return caches;
    }
}

context中存放了当前cache的操作类型、目标对象、目标方法、参数信息，这样我们可以根据这些信息来决定使用那些cache； context.getOperation().getCacheNames()得到当前目标对象/目标方法上配置的cache Name；然后我们可以在此基础上添加额外的cache。

 

 

此处需要注意的是即使配置了CacheResolver，也必须在@CacheConfig或方法上的如@CachePut上指定至少一个Cache Name。

 

4、CacheErrorHandler

用于捕获从Cache中进行CRUD时的异常的回调处理器。

本文转自http://jinnianshilongnian.iteye.com/blog/2105367