package com.cache;import java.util.Map;import java.util.concurrent.ConcurrentHashMap;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;public class MapCacheManager {    private final static Log log = LogFactory.getLog(MapCacheManager.class);    private volatile long updateTime = 0L;// 更新缓存时记录的时间    private volatile boolean updateFlag = true;// 正在更新时的阀门，为false时表示当前没有更新缓存，为true时表示当前正在更新缓存    private volatile static MapCacheManager mapCacheObject;// 缓存实例对象    private static Map
     
       cacheMap = new ConcurrentHashMap
      
       ();// 缓存容器    private MapCacheManager() {        this.LoadCache();// 加载缓存        updateTime = System.currentTimeMillis();// 缓存更新时间    }    /**     * 采用单例模式获取缓存对象实例     *      * @return     */    public static MapCacheManager getInstance() {        if (null == mapCacheObject) {            synchronized (MapCacheManager.class) {                if (null == mapCacheObject) {                    mapCacheObject = new MapCacheManager();                }            }        }        return mapCacheObject;    }    /**     * 装载缓存     */    private void LoadCache() {        this.updateFlag = true;// 正在更新        /********** 数据处理，将数据放入cacheMap缓存中 **begin ******/        cacheMap.put("key1", "value1");        cacheMap.put("key2", "value2");        cacheMap.put("key3", "value3");        cacheMap.put("key4", "value4");        cacheMap.put("key5", "value5");        /********** 数据处理，将数据放入cacheMap缓存中 ***end *******/        this.updateFlag = false;// 更新已完成    }    /**     * 返回缓存对象     *      * @return     */    public Map
       
         getMapCache() {        long currentTime = System.currentTimeMillis();        if (this.updateFlag) {
   // 前缓存正在更新            log.info("cache is Instance .....");            return null;        }        if (this.IsTimeOut(currentTime)) {
   // 如果当前缓存正在更新或者缓存超出时限，需重新加载            synchronized (this) {                this.ReLoadCache();                this.updateTime = currentTime;            }        }        return this.cacheMap;    }    private boolean IsTimeOut(long currentTime) {        return ((currentTime - this.updateTime) > 1000000);// 超过时限，超时    }    /**     * 获取缓存项大小     * @return     */    private int getCacheSize() {        return cacheMap.size();    }    /**     * 获取更新时间     * @return     */    private long getUpdateTime() {        return this.updateTime;    }    /**     * 获取更新标志     * @return     */    private boolean getUpdateFlag() {        return this.updateFlag;    }    /**     * 重新装载     */    private void ReLoadCache() {        this.cacheMap.clear();        this.LoadCache();    }}
       
      
     

测试实例：

package com.cache;import java.util.Iterator;import java.util.Map;import java.util.Set;import java.util.concurrent.ConcurrentHashMap;public class CacheTest {    public static void main(String[] args) {                MapCacheManager cache = MapCacheManager.getInstance();        Map
     
       cacheMap = new ConcurrentHashMap
      
       ();                cacheMap = cache.getMapCache();        Set
       
         set = cacheMap.keySet();        Iterator
        
          it = set.iterator();                while(it.hasNext()){            String key = it.next();            System.out.println(key+"="+cacheMap.get(key));        }    }}