帶過期時間的Map

import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

/**
 * <p>
 * Title: ExpireMap
 * </p>
 * 
 * <p>
 * Description: 設定map過期時間
 * </p>
 * 
 * <p>
 * Company: 
 * </p>
 * 
 * @author
 * 
 * @since：2020-7-28 下午05:23:25
 * 
 */
public class ExpiryMap<K, V> extends HashMap<K, V> {
	private static final long serialVersionUID = 1L;

	/**
	 * 過期時間設定為3分鐘，可以修改
	 */
	private long EXPIRY = 1000 * 60 * 3;

	private HashMap<K, Long> expiryMap = new HashMap();

	public ExpiryMap() {
		super();
	}

	public ExpiryMap(long defaultExpiryTime) {
		this(1 << 4, defaultExpiryTime);
	}

	public ExpiryMap(int initialCapacity, long defaultExpiryTime) {
		super(initialCapacity);
		this.EXPIRY = defaultExpiryTime;
	}

	public V put(K key, V value) {
		expiryMap.put(key, System.currentTimeMillis() + EXPIRY);
		return super.put(key, value);
	}

	public boolean containsKey(Object key) {
		return !checkExpiry(key, true) && super.containsKey(key);
	}

	/**
	 * @param key
	 * @param value
	 * @param expiryTime
	 *            鍵值對有效期 毫秒
	 * @return
	 */
	public V put(K key, V value, long expiryTime) {
		expiryMap.put(key, System.currentTimeMillis() + expiryTime);
		return super.put(key, value);
	}

	public int size() {
		return entrySet().size();
	}

	public boolean isEmpty() {
		return entrySet().size() == 0;
	}

	public boolean containsValue(Object value) {
		if (value == null)
			return Boolean.FALSE;
		Set<java.util.Map.Entry<K, V>> set = super.entrySet();
		Iterator<java.util.Map.Entry<K, V>> iterator = set.iterator();
		while (iterator.hasNext()) {
			java.util.Map.Entry<K, V> entry = iterator.next();
			if (value.equals(entry.getValue())) {
				if (checkExpiry(entry.getKey(), false)) {
					iterator.remove();
					return Boolean.FALSE;
				} else
					return Boolean.TRUE;
			}
		}
		return Boolean.FALSE;
	}

	public Collection<V> values() {

		Collection<V> values = super.values();

		if (values == null || values.size() < 1)
			return values;

		Iterator<V> iterator = values.iterator();

		while (iterator.hasNext()) {
			V next = iterator.next();
			if (!containsValue(next))
				iterator.remove();
		}
		return values;
	}

	public V get(Object key) {
		if (key == null)
			return null;
		if (checkExpiry(key, true))
			return null;
		return super.get(key);
	}

	/**
	 * 
	 * @Description: 是否過期
	 * @param key
	 * @return null:不存在或key為null -1:過期 存在且沒過期傳回value 因為過期的不是實時删除，是以稍微有點作用
	 */
	public Object isInvalid(Object key) {
		if (key == null)
			return null;
		if (!expiryMap.containsKey(key)) {
			return null;
		}
		long expiryTime = expiryMap.get(key);

		boolean flag = System.currentTimeMillis() > expiryTime;

		if (flag) {
			super.remove(key);
			expiryMap.remove(key);
			return -1;
		}
		return super.get(key);
	}

	public void putAll(Map<? extends K, ? extends V> m) {
		for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
			expiryMap.put(e.getKey(), System.currentTimeMillis() + EXPIRY);
		super.putAll(m);
	}

	public Set<Map.Entry<K, V>> entrySet() {
		Set<java.util.Map.Entry<K, V>> set = super.entrySet();
		Iterator<java.util.Map.Entry<K, V>> iterator = set.iterator();
		while (iterator.hasNext()) {
			java.util.Map.Entry<K, V> entry = iterator.next();
			if (checkExpiry(entry.getKey(), false))
				iterator.remove();
		}

		return set;
	}

	/**
	 * 
	 * @Description: 是否過期
	 * @param
	 * 
	 * @param isRemoveSuper
	 *            true super删除
	 * @return
	 */
	private boolean checkExpiry(Object key, boolean isRemoveSuper) {

		if (!expiryMap.containsKey(key)) {
			return Boolean.FALSE;
		}
		long expiryTime = expiryMap.get(key);

		boolean flag = System.currentTimeMillis() > expiryTime;

		if (flag) {
			if (isRemoveSuper)
				super.remove(key);
			expiryMap.remove(key);
		}
		return flag;
	}
}