package com.zuidaima.modules.common.util;import java.util.AbstractMap;import java.util.HashMap;import java.util.HashSet;import java.util.Map;import java.util.Set;/** * 用来存储短暂对象的缓存类，实现Map接口，，内部有一个定时器用来清除过期（30秒）的对象。 * 为避免创建过多线程，没有特殊要求请使用getDefault()方法来获取本类的实例。 * @author * @param <K> * @param <V> */public class CacheMap<K, V> extends AbstractMap<K, V> {private static final long DEFAULT_TIMEOUT = 30000;private static CacheMap<Object, Object> defaultInstance;public static synchronized final CacheMap<Object, Object> getDefault() {if (defaultInstance == null) {defaultInstance = new CacheMap<Object, Object>(DEFAULT_TIMEOUT);}return defaultInstance;}private class CacheEntry implements Entry<K, V> {long time;V value;K key;CacheEntry(K key, V value) {super();this.value = value;this.key = key;this.time = System.currentTimeMillis();}@Overridepublic K getKey() {return key;}@Overridepublic V getValue() {return value;}@Overridepublic V setValue(V value) {return this.value = value;}}private class ClearThread extends Thread {ClearThread() {setName("clear cache thread");}public void run() {while (true) {try {long now = System.currentTimeMillis();Object[] keys = map.keySet().toArray();for (Object key : keys) {CacheEntry entry = map.get(key);if (now – entry.time >= cacheTimeout) {synchronized (map) {map.remove(key);}}}Thread.sleep(cacheTimeout);} catch (Exception e) {e.printStackTrace();}}}}private long cacheTimeout;private Map<K, CacheEntry> map = new HashMap<K, CacheEntry>();public CacheMap(long timeout) {this.cacheTimeout = timeout;new ClearThread().start();}@Overridepublic Set<Entry<K, V>> entrySet() {Set<Entry<K, V>> entrySet = new HashSet<Map.Entry<K, V>>();Set<Entry<K, CacheEntry>> wrapEntrySet = map.entrySet();for (Entry<K, CacheEntry> entry : wrapEntrySet) {entrySet.add(entry.getValue());}return entrySet;}@Overridepublic V get(Object key) {CacheEntry entry = map.get(key);return entry == null ? null : entry.value;}@Overridepublic V put(K key, V value) {CacheEntry entry = new CacheEntry(key, value);synchronized (map) {map.put(key, entry);}return value;}}
少吃点，吃好的。
