SpringBootCache源码解析：Cache自动配置

# . Auto Configure
org. springframework. boot. autoconfigure . EnableAutoConfiguration=\
org. springframework . boot . autoconfigure . cache . CacheAutoConfiguration, \
下面先来看 CacheAutoConfiguration 类的注解部分代码实现。
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass (CacheManager. class)
@ConditionalOnBeanCacheAspectSupport . class)
@ConditionalOnMissingBean(value = CacheManager .class, name = "cacheResolve
r")
@EnableConfigurationProperties (CacheProperties. class)
@AutoConfigureAfter({ CouchbaseAutoConfiguration. class, HazelcastAutoConfig
uration. class,
HibernateJpaAutoConfiguration. class, RedisAutoConfigur
ation.class })
@Import(CacheConfigurat ionImportSelector.class)
public class CacheAutoConfiguration {
}

public interface CacheManager {
//根据名称获取缓存
@Nullable
Cache getCache(String name);
//获取缓存名称集合
Collection<String> getCacheNames();
}

static class CacheConfigurat ionImportSelector implements ImportSelector {
public String[] selectImports(Annotat ionMetadata importingClassMetadata)
CacheType[] types = CacheType.values();
for(inti=0:i<types.leneth:1t+)5
imports[i] = CacheConfigurations . getConfigurat ionClass(types[i]);
return imports; }
}

//支持的缓存类型(按照优先级定义)
public enum CacheType {
//使用上下文中的 Cache Bean 进行通用缓存
GENERIC,
// JCache(JSR- 107) 支持的缓存
JCACHE,
// EhCache 支持的缓存
EHCACHE,
// Hazelcast 支持的缓存
HAZELCAST,
// Infinispan 支持的缓存
INFINISPAN,
// Couchbase. 支持的缓存
COUCHBASE,
// Redis.支持的缓存
REDIS,
// Caffeine 支持的缓存
CAFFEINE,
//内存基本的简单缓存
SIMPLE,
// 不支持缓存
NONE
}

final class CacheConfigurations {
private static final Map<CacheType, Class<?>> MAPPINGS;
//定义 CacheType 5@Conf iguration 之间的对应关系
static {
Map<CacheType, Class<?>> mappings = new EnumMap<>(CacheType.class);
mappings . put(CacheType . GENERIC, GenericCacheConfiguration.class);mappings . put(CacheType . EHCACHE，EhCacheCacheConfiguration. class);
mappings . put (CacheType . HAZELCAST, HazelcastCacheConfiguration. class);
mappings . put(CacheType . INF INISPAN, InfinispanCacheConfiguration.class);
mappings . put (CacheType . JCACHE, JCacheCacheConfiguration. class);
mappings . put (CacheType . COUCHBASE, CouchbaseCacheConfiguration. class);
mappings . put (CacheType. REDIS, RedisCacheConfiguration.class);
mappings . put(CacheType . CAFFEINE, CaffeineCacheConfiguration. class);
mappings . put(CacheType . SIMPLE, SimpleCacheConfiguration.class);
mappings . put(CacheType . NONE, NoOpCacheConfiguration.class);
MAPPINGS = Collections . unmodifiableMap(mappings);
//根据 CacheType
型获得对应的@Configuration 类
static String getConfigurationClass(CacheType cacheType) {
Class<?> configurationClass = MAPPINGS . get(cacheType);
Assert.state(configurationClass != null, () -> "Unknown cache type ”+
cacheType) ;
return configurationClass . getName();
}
}

@Configurat ion(proxyBeanMethods = false)
@ConditionalOnBean(Cache . class)
@ConditionalOnMissingBean(CacheManager . class)
@Conditional(CacheCondition. class)
class GenericCacheConfiguration {
@Bean
SimpleCacheManager cacheManager(CacheManagerCustomizers customizers, Coll
ection
<Cache> caches) {
SimpleCacheManager cacheManager = new SimpleCacheManager();
cacheManager . setCaches(caches);
return customizers . customize(cacheManager);
}}

class CacheCondition extends SpringBootCondition {
@Override
public ConditionOutcome getMatchOutcome (ConditionContext context, Annot
ated-
TypeMetadata metadata) {
String sourceClass =
if (metadata instanceof ClassMetadata) {
sourceClass = ((ClassMetadata) metadata). getClassName() ;
Condit ionMessage . Builder message = ConditionMessage . forCondition("C
ache" ,
sourceClass);
Environment environment = context . getEnvironment( ) ;
try {
//创建指定环境的 Binder, 然后绑定属性到对象上
BindResult<CacheType> specified = Binder . get( environment) . bind
("spring.
cache. type", CacheType . class);
//如果未绑定，则返回匹配
if (!specified. isBound()) {
return ConditionOutcome . match(message . because("automatic ca
che type"));
//获取所需的缓存类型
CacheType required = CacheConfigurations . getType(((AnnotationMe
tadata)
metadata) . getClassName());
//如果已绑定，并且绑定的类型与所需的缓存类型相同，则返回匹配
if (specified.get() == required) {return Conditi onOutcome . match(message. because(specified. get
() +”cache type"));
} catch (BindException ex) {
//其他情况则返回不匹配
return ConditionOutcome . noMatch(message . because("unknown cache typ
e"));
}
}

public class SimpleCacheManager extends AbstractCacheManager {
private Collection<? extends Cache> caches = Collections . emptySet();
//设置缓存集合
public void setCaches (Collection<? extends Cache> caches) {
this.caches = caches;
//获取缓存集合
@Override
protected Collection<? extends Cache> loadCaches() {
return this. caches;
}
}

@ConditionalOnClass(LocalContainerEnt ityManagerFactoryBean. class)
@Conditiona lOnBean(AbstractEntityManagerFactoryBean.class)
static class CacheManagerEntityManagerFactoryDependsOnPostProcessor
extends EntityManagerFactoryDependsOnPostProcessor {
CacheManagerEntityManagerFactoryDependsOnPostProcessor() {
super("cacheManager");}
}

//实例化 CacheManagerCus tomizers
@Bean
@ConditionalOnMissingBean
public CacheManagerCustomizers cacheManagerCustomizers(
ObjectProvider<CacheManagerCustomizer<?>> customizers) {
return new CacheManagerCustomizers(
customi zers . orderedStream(). collect(Collectors . toList()));
}

//实例化 CacheManagerVal idator
@Bean
public CacheManagerValidator cacheAutoConfigurat ionValidator(CachePropert
ies-
cachePropert
ies,
objectProvid
er<CacheManager> cacheManager) {
return new CacheManagerValidator(cacheProperties, cacheManager);
// CacheManagerVal idator 的具体定义，用于检查并抛出有意义的异常 static class
CacheManagerValidator implements InitializingBean {private final CacheProperties cacheProperties;
private final objectProvider<CacheManager> cacheManager;
CacheManagerValidator(CacheProperties cacheProperties, objectProviderkCac
he-
Manager> cacheManager) {
this. cacheProperties = cacheProperties;
this. cacheManager = cacheManager;
}
@Override
public void afterPropertiesSet() {
Assert . notNull(this . cacheManager . getIfAvailable(),
) -> "No cache manager could be auto- configured, check
your configuration (caching ”+ "type is” + this. cacheProperties .getType
() + "')");
}
}