如何基于LoadingCache實(shí)現(xiàn)Java本地緩存

<dependency>
  <groupId>com.google.guava</groupId>
  <artifactId>guava</artifactId>
  <version>27.1-jre</version>
</dependency>

LoadingCache<Long, String> cache = CacheBuilder.newBuilder()
        //緩存池大小，在緩存項(xiàng)接近該大小時， Guava開始回收舊的緩存項(xiàng)
        .maximumSize(GUAVA_CACHE_SIZE)
        //設(shè)置時間對象沒有被讀/寫訪問則對象從內(nèi)存中刪除(在另外的線程里面不定期維護(hù))
        .expireAfterAccess(10, TimeUnit.MINUTES)
        //移除監(jiān)聽器,緩存項(xiàng)被移除時會觸發(fā)
        .removalListener(new RemovalListener <Long, String>() {
          @Override
          public void onRemoval(RemovalNotification<Long, String> rn) {
            //執(zhí)行邏輯操作
          }
        })
        //開啟Guava Cache的統(tǒng)計(jì)功能
        .recordStats()
        .build(cacheLoader);

package com.xxx;

import com.google.common.cache.*;
import org.slf4j.Logger;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.TimeUnit;

public class CacheManager {

  private static Logger log = Log.get();

  /** 緩存項(xiàng)最大數(shù)量 */
  private static final long GUAVA_CACHE_SIZE = 100000;

  /** 緩存時間：天 */
  private static final long GUAVA_CACHE_DAY = 10;

  /** 緩存操作對象 */
  private static LoadingCache<Long, String> GLOBAL_CACHE = null;

  static {
    try {
      GLOBAL_CACHE = loadCache(new CacheLoader <Long, String>() {
        @Override
        public String load(Long key) throws Exception {
          // 處理緩存鍵不存在緩存值時的處理邏輯
          return "";
        }
      });
    } catch (Exception e) {
      log.error("初始化Guava Cache出錯", e);
    }
  }

  /**
   * 全局緩存設(shè)置
   *
   * 緩存項(xiàng)最大數(shù)量：100000
   * 緩存有效時間（天）：10
   *
   *
   * @param cacheLoader
   * @return
   * @throws Exception
   */
  private static LoadingCache<Long, String> loadCache(CacheLoader<Long, String> cacheLoader) throws Exception {
    LoadingCache<Long, String> cache = CacheBuilder.newBuilder()
        //緩存池大小，在緩存項(xiàng)接近該大小時， Guava開始回收舊的緩存項(xiàng)
        .maximumSize(GUAVA_CACHE_SIZE)
        //設(shè)置時間對象沒有被讀/寫訪問則對象從內(nèi)存中刪除(在另外的線程里面不定期維護(hù))
        .expireAfterAccess(GUAVA_CACHE_DAY, TimeUnit.DAYS)
        // 設(shè)置緩存在寫入之后 設(shè)定時間 后失效
        .expireAfterWrite(GUAVA_CACHE_DAY, TimeUnit.DAYS)
        //移除監(jiān)聽器,緩存項(xiàng)被移除時會觸發(fā)
        .removalListener(new RemovalListener <Long, String>() {
          @Override
          public void onRemoval(RemovalNotification<Long, String> rn) {
            //邏輯操作
          }
        })
        //開啟Guava Cache的統(tǒng)計(jì)功能
        .recordStats()
        .build(cacheLoader);
    return cache;
  }

  /**
   * 設(shè)置緩存值
   * 注: 若已有該key值，則會先移除(會觸發(fā)removalListener移除監(jiān)聽器)，再添加
   *
   * @param key
   * @param value
   */
  public static void put(Long key, String value) {
    try {
      GLOBAL_CACHE.put(key, value);
    } catch (Exception e) {
      log.error("設(shè)置緩存值出錯", e);
    }
  }

  /**
   * 批量設(shè)置緩存值
   *
   * @param map
   */
  public static void putAll(Map<? extends Long, ? extends String> map) {
    try {
      GLOBAL_CACHE.putAll(map);
    } catch (Exception e) {
      log.error("批量設(shè)置緩存值出錯", e);
    }
  }

  /**
   * 獲取緩存值
   * 注：如果鍵不存在值，將調(diào)用CacheLoader的load方法加載新值到該鍵中
   *
   * @param key
   * @return
   */
  public static String get(Long key) {
    String token = "";
    try {
      token = GLOBAL_CACHE.get(key);
    } catch (Exception e) {
      log.error("獲取緩存值出錯", e);
    }
    return token;
  }

    /**
   * 移除緩存
   *
   * @param key
   */
  public static void remove(Long key) {
    try {
      GLOBAL_CACHE.invalidate(key);
    } catch (Exception e) {
      log.error("移除緩存出錯", e);
    }
  }

  /**
   * 批量移除緩存
   *
   * @param keys
   */
  public static void removeAll(Iterable<Long> keys) {
    try {
      GLOBAL_CACHE.invalidateAll(keys);
    } catch (Exception e) {
      log.error("批量移除緩存出錯", e);
    }
  }

  /**
   * 清空所有緩存
   */
  public static void removeAll() {
    try {
      GLOBAL_CACHE.invalidateAll();
    } catch (Exception e) {
      log.error("清空所有緩存出錯", e);
    }
  }

  /**
   * 獲取緩存項(xiàng)數(shù)量
   *
   * @return
   */
  public static long size() {
    long size = 0;
    try {
      size = GLOBAL_CACHE.size();
    } catch (Exception e) {
      log.error("獲取緩存項(xiàng)數(shù)量出錯", e);
    }
    return size;
  }
}