浅析SpringBoot缓存原理探究、SpringCache常用注解介绍及如何集成Redis

(1)Generic
(2)JCache (JSR-107)(EhCache 3、Hazelcast、Infinispan等)
(3)EhCache 2.x
(4)Hazelcast
(5)Infinispan
(6)Couchbase
(7)Redis
(8)Caffeine
(9)Simple
(10)NoOp

org.springframework.boot.autoconfigure.cache.GenericCacheConfiguration
org.springframework.boot.autoconfigure.cache.JCacheCacheConfiguration
org.springframework.boot.autoconfigure.cache.EhCacheCacheConfiguration
org.springframework.boot.autoconfigure.cache.HazelcastCacheConfiguration
org.springframework.boot.autoconfigure.cache.InfinispanCacheConfiguration
org.springframework.boot.autoconfigure.cache.CouchbaseCacheConfiguration
org.springframework.boot.autoconfigure.cache.RedisCacheConfiguration
org.springframework.boot.autoconfigure.cache.CaffeineCacheConfiguration
org.springframework.boot.autoconfigure.cache.SimpleCacheConfiguration  // 默认
org.springframework.boot.autoconfigure.cache.NoOpCacheConfiguration

// 源码
@ConditionalOnMissingBean({CacheManager.class})
@Conditional({CacheCondition.class})
class SimpleCacheConfiguration {
    SimpleCacheConfiguration() {
}

@Service
@CacheConfig(cacheNames = "categories")
public class CategoryServiceImpl implements CategoryService{}

// 可从其源码看出
public @interface Caching {
    Cacheable[] cacheable() default {};
    CachePut[] put() default {};
    CacheEvict[] evict() default {};
}

@Caching(evict = {
　　@CacheEvict(cacheNames = "eventAskMaxId", key = "#ask.eventId", condition = "#ask.eventId != null"),
　　@CacheEvict(cacheNames = "eventAskTotal", key = "#ask.eventId", condition = "#ask.eventId != null")
})
public void insert(EventAsk ask) {}

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

public class Table implements Serializable {}

// RedisAutoConfiguration源码
@Bean
@ConditionalOnMissingBean( name = {"redisTemplate"} )// 可以自定义redisTemplate替换默认的
public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {
    // 默认没有做额外的序列化（使用的RedisTemplate默认序列化），redis对象都是需要序列化的
    // 两个泛型都是Object，需要强制转换为<String, Object>
    RedisTemplate<Object, Object> template = new RedisTemplate();
    template.setConnectionFactory(redisConnectionFactory);
    return template;
}

@Bean
@ConditionalOnMissingBean
// 由于String 是redis最常用的类型，所以单独提供了StringRedisTemplate
public StringRedisTemplate stringRedisTemplate(RedisConnectionFactory redisConnectionFactory) throws UnknownHostException {
    StringRedisTemplate template = new StringRedisTemplate();
    template.setConnectionFactory(redisConnectionFactory);
    return template;
}

// RedisTemplate源码
if (this.defaultSerializer == null) {
    // RedisTemplate默认配置了JDK序列化
    this.defaultSerializer = new JdkSerializationRedisSerializer(...);
}

public class FastJsonRedisSerializer<T> implements RedisSerializer<T> {}

@Slf4j
@Configuration
@EnableCaching
@ConditionalOnClass(RedisOperations.class)
@EnableConfigurationProperties(RedisProperties.class)
public class RedisConfig extends CachingConfigurerSupport {
    // 1、解决序列化问题
    @Bean(name = "redisTemplate")
    @SuppressWarnings("unchecked")
    @ConditionalOnMissingBean(name = "redisTemplate")
    public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
        RedisTemplate<Object, Object> template = new RedisTemplate<>();
        //使用fastjson序列化
        FastJsonRedisSerializer fastJsonRedisSerializer = new FastJsonRedisSerializer(Object.class);
        // ......
        return template;
    }

    // 2、设置key默认过期时间
    @Bean
    public CacheManager cacheManager(RedisConnectionFactory redisConnectionFactory) {
        return new RedisCacheManager(RedisCacheWriter.nonLockingRedisCacheWriter(redisConnectionFactory),
            this.redisCacheConfiguration(1800),     // 默认配置
            this.initialCacheConfigurations());    // 指定key过期时间配置
    }
    // 3、配置redis挂掉后，捕获异常,不影响查询数据库
    public CacheErrorHandler errorHandler() {
        CacheErrorHandler cacheErrorHandler = new CacheErrorHandler() {
　　　　　　......
        };
        return cacheErrorHandler;
    }

}