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：

Java代码


<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：

Java代码


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：

Java代码


@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：

Java代码


@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：

Java代码


@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：

Java代码


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