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();
}
}