The Ehcache second-level cache provider for Hibernate is deprecated

当我们使用hibernate-ehcache包（Ehcache 2）作为hibernate二级缓存时，系统会提示警告说已经过时了，那这时候找到spring boot推荐的新的二级缓存方案，现在推荐hibernate-jcache，可以与Ehcache 3或是其他实现了javax.cache.spi.CachingProvider的缓存自动集成

jcache是一种缓存门面规范，并不包含具体缓存实现，spring boot推荐与jcache搭配使用的是Hazelcast，Hazelcast实现了CachingProvider，可以直接作为hibernate二级缓存，Hazelcast实现下一篇再提供

hibernate二级缓存重构之后，要自己实现也非常简单，只需要实现

org.hibernate.cache.spi.support.RegionFactoryTemplate

org.hibernate.cache.spi.support.DomainDataStorageAccess

这两个类就可以了，引入caffeine包

<dependency><groupId>com.github.ben-manes.caffeine</groupId><artifactId>caffeine</artifactId>
</dependency>

下面是DomainDataStorageAccess实现，这个类就是缓存操作的实现

import java.util.concurrent.TimeUnit;import org.apache.commons.lang3.StringUtils;
import org.hibernate.cache.spi.support.DomainDataStorageAccess;
import org.hibernate.engine.spi.SharedSessionContractImplementor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;import com.github.benmanes.caffeine.cache.Cache;
import com.github.benmanes.caffeine.cache.Caffeine;import lombok.NonNull;public class CaffeineDataRegion implements DomainDataStorageAccess {protected final Logger log = LoggerFactory.getLogger(this.getClass());/*** Region regionName*/private final String regionName;private final Cache<Object, Object> cache;private final int expiryInSeconds; // secondsstatic final int DEFAULT_EXPIRY_IN_SECONDS = 1800;public CaffeineDataRegion(@NonNull String regionName) {this.regionName = StringUtils.replace(regionName, ".", ":") + ":";this.expiryInSeconds = DEFAULT_EXPIRY_IN_SECONDS;cache = Caffeine.newBuilder()// 设置cache中的数据在写入之后的存活时间.expireAfterWrite(30, TimeUnit.MINUTES)// 构建cache实例.build();log.debug("caffeiene region={}, expiryInSeconds={}", regionName, expiryInSeconds);}/*** confirm the specified key exists in current region** @param key*            cache key* @return if cache key is exists in current region return true, else return*         false*/@Overridepublic boolean contains(Object key) {try {log.debug("contains key={}", key);return cache.getIfPresent(key) != null;} catch (Exception ignored) {log.warn("Fail to exists key. key=" + key, ignored);return false;}}@Overridepublic Object getFromCache(Object key, SharedSessionContractImplementor session) {try {return cache.getIfPresent(key);} catch (Exception ignored) {log.warn("Fail to get cache item... key=" + key, ignored);return null;}}@Overridepublic void putIntoCache(Object key, Object value, SharedSessionContractImplementor session) {try {cache.put(key, value);} catch (Exception ignored) {log.warn("Fail to put cache item... key=" + key, ignored);}}@Overridepublic void evictData() {try {cache.invalidateAll();} catch (Exception ignored) {log.warn("Fail to clear region... name=" + regionName, ignored);}}@Overridepublic void evictData(Object key) {try {cache.invalidate(key);} catch (Exception ignored) {log.warn("Fail to remove cache item... key=" + key, ignored);}}@Overridepublic void release() {}
}

下面是RegionFactoryTemplate实现，这个类是缓存启动类

import java.util.Map;import org.hibernate.boot.spi.SessionFactoryOptions;
import org.hibernate.cache.cfg.spi.DomainDataRegionBuildingContext;
import org.hibernate.cache.cfg.spi.DomainDataRegionConfig;
import org.hibernate.cache.spi.support.DomainDataStorageAccess;
import org.hibernate.cache.spi.support.RegionFactoryTemplate;
import org.hibernate.cache.spi.support.StorageAccess;
import org.hibernate.engine.spi.SessionFactoryImplementor;import com.bc.plugin.caffeine.hibernate.regions.CaffeineDataRegion;import lombok.extern.slf4j.Slf4j;@Slf4j
public class CaffeineRegionFactory extends RegionFactoryTemplate {private static final long serialVersionUID = 1L;@Overrideprotected StorageAccess createQueryResultsRegionStorageAccess(String regionName,SessionFactoryImplementor sessionFactory) {return new CaffeineDataRegion(regionName);}@Overrideprotected StorageAccess createTimestampsRegionStorageAccess(String regionName,SessionFactoryImplementor sessionFactory) {return new CaffeineDataRegion(regionName);}@Overrideprotected DomainDataStorageAccess createDomainDataStorageAccess(DomainDataRegionConfig regionConfig,DomainDataRegionBuildingContext buildingContext) {return new CaffeineDataRegion(regionConfig.getRegionName());}@Overrideprotected void prepareForUse(SessionFactoryOptions settings, @SuppressWarnings("rawtypes") Map configValues) {log.debug("RegionFactory is starting... options={}, properties={}", settings, configValues);}@Overrideprotected void releaseFromUse() {}
}

然后配置spring.jpa.properties.hibernate.cache.region.factory_class=/*org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory  */

org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory是hibernate-ehcache包中的实现，

替换成我们CaffeineRegionFactory类的全路径就可以了

引入caffeine包后，spring cache也会使用caffeine，springboot会自动配置caffeine