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CacheExpire.java
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70 lines (58 loc) · 1.8 KB
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package cache.expire;
import cache.Cache;
import cache.ICacheExpire;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
public class CacheExpire<K, V> implements ICacheExpire<K, V> {
// 需要进行过期处理的缓存
private final Cache<K, V> cache;
// 用来储存key对应的过期时间的map
private final Map<K, Long> expireMap = new HashMap<>();
// 用一个定时线程池用来执行删除操作
private static final ScheduledExecutorService expireThread = Executors.newSingleThreadScheduledExecutor();
/**
* 指定某个key过期的时间
* @param key key
* @param expireAt 什么时候过期
*/
@Override
public void expire(K key, long expireAt) {
this.expireMap.put(key, expireAt);
}
public CacheExpire(Cache<K, V> cache) {
this.cache = cache;
init();
}
/**
* 设定单例定时线程的执行参数
*/
private void init() {
expireThread.scheduleAtFixedRate(new ExpireCacheThread(), 1000, 1000, TimeUnit.MILLISECONDS);
}
/**
* 用来执行清除过期缓存
*/
private class ExpireCacheThread implements Runnable {
@Override
public void run() {
Set<Map.Entry<K, Long>> entries = expireMap.entrySet();
for (Map.Entry<K, Long> entry : entries) {
expireCache(entry.getKey(), entry.getValue());
}
}
}
/**
* @param key
* @param expireAt
*/
private void expireCache(K key, long expireAt) {
long nowTime = System.currentTimeMillis();
if (nowTime > expireAt) {
cache.remove(key);
}
}
}