Spring-Cache是Spring3.1引入的基于注解的緩存技術(shù)，本質(zhì)上它并不是一個(gè)具體的緩存實(shí)現(xiàn)，而是一個(gè)對(duì)緩存使用的抽象，通過Spring AOP技術(shù)，在原有的代碼上添加少量的注解來(lái)實(shí)現(xiàn)將這個(gè)方法轉(zhuǎn)成緩存方法的效果。

本來(lái)想來(lái)個(gè)分析源碼，奈何水平有限，先從實(shí)戰(zhàn)搞起。

先引入依賴：

<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-redis</artifactId> <version>2.1.6.RELEASE</version></dependency><dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> <version>2.9.3</version></dependency>

redis配置：

server: port: 8000spring: redis: host: 23.95.x.x port: 6379 timeout: 20s database: 0 jedis: pool: max-active: 5 max-idle: 3 max-wait: 5s password: testtest

配置類：

package me.yanand.config;import org.springframework.cache.annotation.EnableCaching;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.data.redis.cache.RedisCacheConfiguration;import org.springframework.data.redis.cache.RedisCacheManager;import org.springframework.data.redis.connection.RedisConnectionFactory;import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;import org.springframework.data.redis.serializer.RedisSerializationContext;import org.springframework.data.redis.serializer.StringRedisSerializer;import java.time.Duration;@Configuration@EnableCachingpublic class RedisConfig{ private Duration timeOut = Duration.ofMinutes(30); @Bean public RedisCacheManager cacheManager(RedisConnectionFactory redisConnectionFactory) { RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig()//設(shè)置緩存超時(shí)時(shí)間 30分鐘.entryTtl(timeOut)//設(shè)置key序列化方式.serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(new StringRedisSerializer()))//設(shè)置value序列化方式.serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(new GenericJackson2JsonRedisSerializer())).disableCachingNullValues(); return RedisCacheManager.builder(redisConnectionFactory).cacheDefaults(config).transactionAware().build(); }}

主要看@EnableCaching注解，這個(gè)注解引入了@Import(CachingConfigurationSelector.class)，通過CachingConfigurationSelector把代理創(chuàng)建類、CacheInterceptor、CacheOperationSource、BeanFactoryCacheOperationSourceAdvisor注入到容器，spring通過CacheInterceptor攔截器攔截相關(guān)帶有@Cacheable、@CacheEvict、@CachePut注解的方法并執(zhí)行相關(guān)緩存操作。

CacheInterceptor相關(guān)源碼：

@Nullableprivate Object execute(final CacheOperationInvoker invoker, Method method, CacheOperationContexts contexts) { if (contexts.isSynchronized()) { CacheOperationContext context = contexts.get(CacheableOperation.class).iterator().next(); //滿足條件執(zhí)行 if (isConditionPassing(context, CacheOperationExpressionEvaluator.NO_RESULT)) { Object key = generateKey(context, CacheOperationExpressionEvaluator.NO_RESULT); Cache cache = context.getCaches().iterator().next(); try { //這里主要看RedisCache的get方法 return wrapCacheValue(method, cache.get(key, () -> unwrapReturnValue(invokeOperation(invoker)))); } catch (Cache.ValueRetrievalException ex) { // The invoker wraps any Throwable in a ThrowableWrapper instance so we // can just make sure that one bubbles up the stack. throw (CacheOperationInvoker.ThrowableWrapper) ex.getCause(); } } else { //不滿足直接執(zhí)行相關(guān)方法 return invokeOperation(invoker); } } ...省略}

RedisCache相關(guān)代碼：

public synchronized <T> T get(Object key, Callable<T> valueLoader) { ValueWrapper result = get(key);//緩存中有值則返回 if (result != null) { return (T) result.get(); }//緩存中不存在則執(zhí)行相關(guān)方法 T value = valueFromLoader(key, valueLoader); put(key, value); return value; }

注解使用：

package me.yanand.dao;import me.yanand.pojo.User;import org.springframework.cache.annotation.CacheEvict;import org.springframework.cache.annotation.Cacheable;import org.springframework.stereotype.Component;@Componentpublic class UserDao { @Cacheable(cacheNames = 'users',key = '#root.targetClass+#name', unless = '#result eq null') public User getUser(String name){ return new User('張三',30); } @CacheEvict(cacheNames = 'users', key = '#root.targetClass+#name') public void delUser(String name){ }}

測(cè)試：

通過postman觸發(fā)相關(guān)方法，現(xiàn)在我們連上redis查看緩存寫入情況

這里我們看到key已經(jīng)寫入，過期時(shí)間也存在

現(xiàn)在我們刪除緩存

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持好吧啦網(wǎng)。