一定時間しか保持しないMap

とりあえず最低限のメソッドしか実装してないけどこんな感じ？？
最初、HashMap を継承して作ろうとか思ったんだけど型推論回りで挫折……
なんかカッコワルイ＞＜

/**
 * 
 */
package org.yoshiori.collection.utils;

import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

/**
 * @author yoshiori
 * 
 */
public class TimeLimitHashMap<K, V> {


	private final Map<K, TimeAndValue> map = new HashMap<K, TimeAndValue>();
	private long timelimit = 5 * 60 * 1000;

	public TimeLimitHashMap() {
	}

	/**
	 * @param timelimit
	 */
	public TimeLimitHashMap(long timelimit) {
		this.timelimit = timelimit;
	}

	@SuppressWarnings("unchecked")
	public boolean containsValue(Object value) {
		clean();
		try {
			TimeAndValue timeAndValue = new TimeAndValue(new Date(), (V) value);
			return map.containsValue(timeAndValue);
		} catch (Exception e) {
			return false;
		}
	}


	public V get(Object key) {
		TimeAndValue timeAndValue = map.get(key);
		clean();
		if(timeAndValue != null){
			return timeAndValue.getValue();
		}
		return null;
	}

	public V put(K key, V value) {
		TimeAndValue timeAndValue = new TimeAndValue(new Date(), value);
		map.put(key, timeAndValue);
		clean();
		return value;
	}


	public V remove(Object key) {
		TimeAndValue timeAndValue = map.remove(key);
		clean();
		if(timeAndValue != null){
			return timeAndValue.getValue();
		}
		return null;
	}

	private void clean(){
		for(Entry<K,TimeAndValue>  entry : map.entrySet()){
			if(checkTimeout(entry.getValue().getTime())){
				map.remove(entry);
			}
		}
	}
	
	public boolean checkTimeout(Date date){
		return System.currentTimeMillis() - date.getTime() > timelimit;
	}

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	private class TimeAndValue {
		/**
		 * @param time
		 * @param value
		 */
		private TimeAndValue(Date time, V value) {
			this.time = time;
			this.value = value;
		}

		/**
		 * @return the time
		 */
		public Date getTime() {
			return time;
		}

		/**
		 * @return the value
		 */
		public V getValue() {
			return value;
		}

		private Date time;
		private V value;


		/*
		 * (non-Javadoc)
		 * 
		 * @see java.lang.Object#hashCode()
		 */
		@Override
		public int hashCode() {
			final int prime = 31;
			int result = 1;
			result = prime * result + ((value == null) ? 0 : value.hashCode());
			return result;
		}

		/*
		 * (non-Javadoc)
		 * 
		 * @see java.lang.Object#equals(java.lang.Object)
		 */
		@Override
		public boolean equals(Object obj) {
			if (this == obj)
				return true;
			if (obj == null)
				return false;
			if (getClass() != obj.getClass())
				return false;
			TimeAndValue other = (TimeAndValue) obj;
			if (value == null) {
				if (other.value != null)
					return false;
			} else if (!value.equals(other.value))
				return false;
			return true;
		}

	}
}

もっと良い書きかたありそう……
教えてエロい人！！

Collections#synchronizedMap 出来るように Map インターフェース持つべきかなぁ……