玩转Spring Cache --- 整合进程缓存之王Caffeine Cache和Ehcache3.x【享学Spring】（上）

public enum CacheType {
  GENERIC, // 使用的SimpleCacheManager(自己手动指定Cache，可任意类型Cache实现哦)
  JCACHE, // 使用org.springframework.cache.jcache.JCacheCacheManager
  EHCACHE, // 使用org.springframework.cache.ehcache.EhCacheCacheManager
  HAZELCAST, // 使用com.hazelcast.spring.cache.HazelcastCacheManager
  INFINISPAN, // 使用org.infinispan.spring.provider.SpringEmbeddedCacheManager
  COUCHBASE, // 使用com.couchbase.client.spring.cache.CouchbaseCacheManager
  REDIS, // 使用org.springframework.data.redis.cache.RedisCacheManager，依赖于RedisTemplate进行操作
  CAFFEINE, // 使用org.springframework.cache.caffeine.CaffeineCacheManager
  @Deprecated
  GUAVA, // 使用org.springframework.cache.guava.GuavaCacheManager，已经过期不推荐使用了
  SIMPLE, // 使用ConcurrentMapCacheManager
  NONE; // 使用NoOpCacheManager，表示禁用缓存
}

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context-support</artifactId>
    <version>5.1.6.RELEASE</version>
</dependency>

<dependency>
    <groupId>com.github.ben-manes.caffeine</groupId>
    <artifactId>caffeine</artifactId>
    <!-- 2019.2最新版本 caffeine是2015年才面市的，发展还是很迅速的-->
    <version>2.7.0</version>
</dependency>

// @since 4.3   Requires Caffeine 2.1 or higher.显然我们都2.7版本 肯定满足呀
public class CaffeineCacheManager implements CacheManager {
  private final ConcurrentMap<String, Cache> cacheMap = new ConcurrentHashMap<>(16);
  // 默认能动态生成Cache，对使用者友好
  private boolean dynamic = true;
  // 默认使用的builder  可通过setCaffeine来自定这个cacheBuilder 
  // cacheBuilder.build()得到一个com.github.benmanes.caffeine.cache.Cache  让可以自定义N个参数
  private Caffeine<Object, Object> cacheBuilder = Caffeine.newBuilder();
  @Nullable
  private CacheLoader<Object, Object> cacheLoader;
  private boolean allowNullValues = true; // 是否允许null值
  // 一样的，两个构造函数。你可以指定，也可以让动态生成
  public CaffeineCacheManager() {
  }
  public CaffeineCacheManager(String... cacheNames) {
    setCacheNames(Arrays.asList(cacheNames));
  }
  ...
  @Override
  @Nullable
  public Cache getCache(String name) {
    Cache cache = this.cacheMap.get(name);
    if (cache == null && this.dynamic) {
      synchronized (this.cacheMap) {
        cache = this.cacheMap.get(name);
        if (cache == null) {
          cache = createCaffeineCache(name);
          this.cacheMap.put(name, cache);
        }
      }
    }
    return cache;
  }
  // CaffeineCache实现了org.springframework.cache.Cache接口
  // 内部实现都是委托给com.github.benmanes.caffeine.cache.Cache<Object, Object>来做的
  protected Cache createCaffeineCache(String name) {
    return new CaffeineCache(name, createNativeCaffeineCache(name), isAllowNullValues());
  }
  ...
}

@EnableCaching
@Configuration
public class CacheConfig extends CachingConfigurerSupport {
    @Bean
    public CacheManager cacheManager() {
        CaffeineCacheManager cacheManager = new CaffeineCacheManager();
        // 方案一(常用)：定制化缓存Cache
        cacheManager.setCaffeine(Caffeine.newBuilder()
                .expireAfterWrite(10, TimeUnit.MINUTES)
                .initialCapacity(100)
                .maximumSize(10_000))
        // 如果缓存种没有对应的value，通过createExpensiveGraph方法同步加载  buildAsync是异步加载
        //.build(key -> createExpensiveGraph(key))
        ;
        // 方案二：传入一个CaffeineSpec定制缓存，它的好处是可以把配置方便写在配置文件里
        //cacheManager.setCaffeineSpec(CaffeineSpec.parse("initialCapacity=50,maximumSize=500,expireAfterWrite=5s"));
        return cacheManager;
    }
}
@Service
public class CacheDemoServiceImpl implements CacheDemoService {
    @Cacheable(cacheNames = "demoCache", key = "#id")
    @Override
    public Object getFromDB(Integer id) {
        System.out.println("模拟去db查询~~~" + id);
        return "hello cache...";
    }
}

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = {RootConfig.class, CacheConfig.class})
public class TestSpringBean {
    @Autowired
    private CacheDemoService cacheDemoService;
    @Autowired
    private CacheManager cacheManager;
    @Test
    public void test1() {
        cacheDemoService.getFromDB(1);
        cacheDemoService.getFromDB(1);
        System.out.println("----------验证缓存是否生效----------");
        Cache cache = cacheManager.getCache("demoCache");
        System.out.println(cache);
        System.out.println(cache.get(1, String.class));
    }
}

模拟去db查询~~~1
----------验证缓存是否生效----------
org.springframework.cache.caffeine.CaffeineCache@4f74980d
hello cache...