解析springboot整合谷歌开源缓存框架Guava Cache原理

 <!--guava依赖包-->
 <dependency>
 <groupId>com.google.guava</groupId>
 <artifactId>guava</artifactId>
 <version>19.0</version>
 </dependency>

@Component
public class BaseCache {
    private Cache<String,Object> tenMinuteCache = CacheBuilder.newBuilder()
            //设置缓存初始大小，应该合理设置，后续会扩容
            .initialCapacity(10)
            //最大值
            .maximumSize(100)
            //并发数设置
            .concurrencyLevel(5)
            //缓存过期时间，写入后10分钟过期
            .expireAfterWrite(600,TimeUnit.SECONDS)
            //统计缓存命中率
            .recordStats()
            .build();

    private Cache<String,Object> oneHourCache = CacheBuilder.newBuilder()
            //设置缓存初始大小，应该合理设置，后续会扩容
            .initialCapacity(30)
            //最大值
            .maximumSize(100)
            //并发数设置
            .concurrencyLevel(5)
            //缓存过期时间，写入后1小时 过期
            .expireAfterWrite(3600,TimeUnit.SECONDS)
            //统计缓存命中率
            .recordStats()
            .build();


    public Cache<String, Object> getOneHourCache() {
        return oneHourCache;
    }
    public void setOneHourCache(Cache<String, Object> oneHourCache) {
        this.oneHourCache = oneHourCache;
    }
    public Cache<String, Object> getTenMinuteCache() {
        return tenMinuteCache;
    }
    public void setTenMinuteCache(Cache<String, Object> tenMinuteCache) {
        this.tenMinuteCache = tenMinuteCache;
    }
}

/**
 * 缓存key管理类
 */
public class CacheKeyManager {

    /**
     * 首页轮播图缓存key
     */
    public static final String INDEX_BANNER_KEY = "index:banner:list";

    /**
     * 首页视频列表缓存key
     */
    public static final String INDEX_VIDEL_LIST = "index:video:list";

    /**
     * 视频详情缓存key, %s是视频id
     */
    public static final String VIDEO_DETAIL = "video:detail:%s";

}

@Service
public class VideoServiceImpl implements VideoService {

    @Autowired
    private VideoMapper videoMapper;
    @Autowired
    private BaseCache baseCache;
    @Override
    public List<Video> listVideo() {
        try{
          Object cacheObj =  baseCache.getTenMinuteCache().get(CacheKeyManager.INDEX_VIDEL_LIST,()->{
                List<Video> videoList = videoMapper.listVideo();
                return videoList;
            });
          if(cacheObj instanceof List){
              List<Video> videoList = (List<Video>)cacheObj;
              return videoList;
          }
        }catch (Exception e){
            e.printStackTrace();
        }
        //可以返回兜底数据，业务系统降级-》SpringCloud专题课程
        return null;
    }

    @Override
    publc List<VideoBanner> listBanner() {
        try{
            Object cacheObj =  baseCache.getTenMinuteCache().get(CacheKeyManager.INDEX_BANNER_KEY, ()->{
                List<VideoBanner> bannerList =  videoMapper.listVideoBanner();
                System.out.println("从数据库里面找轮播图列表");
                return bannerList;
            });
            if(cacheObj instanceof List){
                List<VideoBanner> bannerList = (List<VideoBanner>)cacheObj;
                return bannerList;
            }
        }catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }

    @Override
    public Video findDetailById(int videoId) {
        //单独构建一个缓存key，每个视频的key是不一样的
        String videoCacheKey = String.format(CacheKeyManager.VIDEO_DETAIL,videoId);
        try{
         Object cacheObject = baseCache.getOneHourCache().get( videoCacheKey, ()->{
                // 需要使用mybaits关联复杂查询
                Video video = videoMapper.findDetailById(videoId);
                return video;
            });

         if(cacheObject instanceof Video){
             Video video = (Video)cacheObject;
             return video;
         }
        }catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }
}