• Guava Cache 工具类 [ GuavaCacheUtil ]



    pom.xml

    
    <dependency>
        <groupId>com.google.guava</groupId>
        <artifactId>guava</artifactId>
        <version>24.0-jre</version>
    </dependency>
    
    


    GuavaCacheUtil.java

    
    package com.app.core.util;
    
    import com.google.common.cache.*;
    import lombok.extern.log4j.Log4j2;
    import org.apache.commons.lang3.ObjectUtils;
    
    import java.util.ArrayList;
    import java.util.List;
    import java.util.Map;
    import java.util.concurrent.ConcurrentMap;
    import java.util.concurrent.TimeUnit;
    
    @Log4j2
    public class GuavaCacheUtil {
        /**
         * 缓存项最大数量
         */
        private static final long GUAVA_CACHE_SIZE = 100000;
        /**
         * 缓存时间:分钟
         */
        private static final long GUAVA_CACHE_TIME = 10;
    
        /**
         * 缓存操作对象
         */
        private static LoadingCache<String, Object> GLOBAL_CACHE = null;
    
        static {
            try {
                GLOBAL_CACHE = loadCache(new CacheLoader<String, Object>() {
                    public Object load(String key) throws Exception {
                        // 该方法主要是处理缓存键不存在缓存值时的处理逻辑
                        if (log.isDebugEnabled())
                            log.debug("Guava Cache缓存值不存在,初始化空值,键名:{}", key);
                        return ObjectUtils.NULL;
                    }
                });
            } catch (Exception e) {
                log.error("初始化Guava Cache出错", e);
            }
        }
    
        /**
         * 全局缓存设置
         * <ul>
         * <li>缓存项最大数量:100000</li>
         * <li>缓存有效时间(分钟):10</li>
         * </ul>
         *
         * @param cacheLoader
         * @return
         * @throws Exception
         */
        private static <K, V> LoadingCache<K, V> loadCache(CacheLoader<K, V> cacheLoader) throws Exception {
            /*
             * maximumSize 缓存池大小,在缓存项接近该大小时, Guava开始回收旧的缓存项 expireAfterAccess 表示最后一次使用该缓存项多长时间后失效 removalListener 移除缓存项时执行的逻辑方法 recordStats 开启Guava Cache的统计功能
             */
            LoadingCache<K, V> cache = CacheBuilder.newBuilder().maximumSize(GUAVA_CACHE_SIZE).expireAfterAccess(GUAVA_CACHE_TIME, TimeUnit.MINUTES)
                    .removalListener(new RemovalListener<K, V>() {
                        public void onRemoval(RemovalNotification<K, V> rn) {
                            if (log.isDebugEnabled())
                                log.debug("Guava Cache缓存回收成功,键:{}, 值:{}", rn.getKey(), rn.getValue());
                        }
                    }).recordStats().build(cacheLoader);
            return cache;
        }
    
        /**
         * 设置缓存值
         *
         * @param key
         * @param value
         */
        public static void put(String key, Object value) {
            try {
                GLOBAL_CACHE.put(key, value);
                if (log.isDebugEnabled())
                    log.debug("缓存命中率:{},新值平均加载时间:{}", getHitRate(), getAverageLoadPenalty());
            } catch (Exception e) {
                log.error("设置缓存值出错", e);
            }
        }
    
        /**
         * 批量设置缓存值
         *
         * @param map
         */
        public static void putAll(Map<? extends String, ? extends Object> map) {
            try {
                GLOBAL_CACHE.putAll(map);
                if (log.isDebugEnabled())
                    log.debug("缓存命中率:{},新值平均加载时间:{}", getHitRate(), getAverageLoadPenalty());
            } catch (Exception e) {
                log.error("批量设置缓存值出错", e);
            }
        }
    
        /**
         * 获取缓存值
         * <p>注:如果键不存在值,将调用CacheLoader的load方法加载新值到该键中</p>
         *
         * @param key
         * @return
         */
        public static Object get(String key) {
            Object obj = null;
            try {
                obj = GLOBAL_CACHE.get(key);
                if (log.isDebugEnabled())
                    log.debug("缓存命中率:{},新值平均加载时间:{}", getHitRate(), getAverageLoadPenalty());
            } catch (Exception e) {
                log.error("获取缓存值出错", e);
            }
            return obj;
        }
    
        /**
         * 获取缓存值
         * <p>注:如果键不存在值,将直接返回 NULL</p>
         *
         * @param key
         * @return
         */
        public static Object getIfPresent(String key) {
            Object obj = null;
            try {
                obj = GLOBAL_CACHE.getIfPresent(key);
                if (log.isDebugEnabled())
                    log.debug("缓存命中率:{},新值平均加载时间:{}", getHitRate(), getAverageLoadPenalty());
            } catch (Exception e) {
                log.error("获取缓存值出错", e);
            }
            return obj;
        }
    
        /**
         * 移除缓存
         *
         * @param key
         */
        public static void remove(String key) {
            try {
                GLOBAL_CACHE.invalidate(key);
                if (log.isDebugEnabled())
                    log.debug("缓存命中率:{},新值平均加载时间:{}", getHitRate(), getAverageLoadPenalty());
            } catch (Exception e) {
                log.error("移除缓存出错", e);
            }
        }
    
        /**
         * 批量移除缓存
         *
         * @param keys
         */
        public static void removeAll(Iterable<String> keys) {
            try {
                GLOBAL_CACHE.invalidateAll(keys);
                if (log.isDebugEnabled())
                    log.debug("缓存命中率:{},新值平均加载时间:{}", getHitRate(), getAverageLoadPenalty());
            } catch (Exception e) {
                log.error("批量移除缓存出错", e);
            }
        }
    
        /**
         * 清空所有缓存
         */
        public static void removeAll() {
            try {
                GLOBAL_CACHE.invalidateAll();
                if (log.isDebugEnabled())
                    log.debug("缓存命中率:{},新值平均加载时间:{}", getHitRate(), getAverageLoadPenalty());
            } catch (Exception e) {
                log.error("清空所有缓存出错", e);
            }
        }
    
        /**
         * 获取缓存项数量
         *
         * @return
         */
        public static long size() {
            long size = 0;
            try {
                size = GLOBAL_CACHE.size();
                if (log.isDebugEnabled())
                    log.debug("缓存命中率:{},新值平均加载时间:{}", getHitRate(), getAverageLoadPenalty());
            } catch (Exception e) {
                log.error("获取缓存项数量出错", e);
            }
            return size;
        }
    
        /**
         * 获取所有缓存项的键
         *
         * @return
         */
        public static List<String> keys() {
            List<String> list = new ArrayList<String>();
            try {
                ConcurrentMap<String, Object> map = GLOBAL_CACHE.asMap();
                for (Map.Entry<String, Object> item : map.entrySet())
                    list.add(item.getKey());
                if (log.isDebugEnabled())
                    log.debug("缓存命中率:{},新值平均加载时间:{}", getHitRate(), getAverageLoadPenalty());
            } catch (Exception e) {
                log.error("获取所有缓存项的键出错", e);
            }
            return list;
        }
    
        /**
         * 缓存命中率
         *
         * @return
         */
        public static double getHitRate() {
            return GLOBAL_CACHE.stats().hitRate();
        }
    
        /**
         * 加载新值的平均时间,单位为纳秒
         *
         * @return
         */
        public static double getAverageLoadPenalty() {
            return GLOBAL_CACHE.stats().averageLoadPenalty();
        }
    
        /**
         * 缓存项被回收的总数,不包括显式清除
         *
         * @return
         */
        public static long getEvictionCount() {
            return GLOBAL_CACHE.stats().evictionCount();
        }
    }
    
    
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  • 原文地址:https://www.cnblogs.com/lalalagq/p/10219397.html
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