Java-ConcurrentHashMap实现缓存、异步

MyCache.java

package cn.pangpython.test.cache;/** * Created by pangPython on 2017/9/25. * * 缓存实体类 */public class MyCache {    private String sessionID;//key    private Object cacheObj;//value    private long lastAccessTime;//最后访问时间    public MyCache(String sessionID, Object cacheObj) {        this.sessionID = sessionID;        this.cacheObj = cacheObj;    }    public MyCache(String sessionID, Object cacheObj, long lastAccessTime) {        this.sessionID = sessionID;        this.cacheObj = cacheObj;        this.lastAccessTime = lastAccessTime;    }    public String getSessionID() {        return sessionID;    }    public void setSessionID(String sessionID) {        this.sessionID = sessionID;    }    public Object getCacheObj() {        return cacheObj;    }    public void setCacheObj(Object cacheObj) {        this.cacheObj = cacheObj;    }    public long getLastAccessTime() {        return lastAccessTime;    }    public void setLastAccessTime(long lastAccessTime) {        this.lastAccessTime = lastAccessTime;    }}

CacheManager.java

package cn.pangpython.test.cache;import java.util.Map;import java.util.concurrent.ConcurrentHashMap;/** * Created by pangPython on 2017/9/25. */public class CacheManager {    private ConcurrentHashMap<String,MyCache> cacheContainer = null;    private static volatile CacheManager m_cacheManager = null;    private long timeout;    public static CacheManager getInstance() {        if(m_cacheManager == null){            synchronized (CacheManager.class){                if(m_cacheManager == null){                    m_cacheManager = new CacheManager(1000*60*30);                }            }        }        return m_cacheManager;    }    private CacheManager(long timeout) {        this.timeout = timeout;        cacheContainer = new ConcurrentHashMap<>();        CacheCleaner cacheCleanerThread = new CacheCleaner();        cacheCleanerThread.start();    }    /**     * 访问缓存     * 每一次访问把最后访问时间改成当前时间     *     * @param key     * @return     */    public MyCache getCache(String key){        MyCache myCache = cacheContainer.get(key);        myCache.setLastAccessTime(System.currentTimeMillis());        cacheContainer.put(key,myCache);        return myCache;    }    /**     * 添加缓存     *     * 默认最后访问时间为当期时间     * @param key     * @param value     */    public void setCache(String key,MyCache value){  //      System.out.println("key:"+key);//        System.out.println("value:"+value);        MyCache myCache = new MyCache(key,value.getCacheObj());        myCache.setLastAccessTime(System.currentTimeMillis());        cacheContainer.put(key,myCache);    }    /**     * 缓存定时清理线程     *     */    class CacheCleaner extends Thread{        @Override        public void run() {            while(true){                /**                 * 30分钟执行一次清理                 *                 */                try {                    Thread.sleep(1000*60*30);                } catch (InterruptedException e) {                    e.printStackTrace();                }                for (Map.Entry<String,MyCache> entry:cacheContainer.entrySet() ) {                    String sessionID = entry.getKey();                    MyCache myCache = entry.getValue();                    if(System.currentTimeMillis() - myCache.getLastAccessTime() >= timeout){                        cacheContainer.remove(sessionID);                    }                }            }        }    }}

CacheTest.java

package cn.pangpython.test.cache;import java.util.Random;/** * Created by pangPython on 2017/9/25. */public class CacheTest {    public static void main(String[] args){        /**         * 比较好的使用场景就是：网络请求的状态下，请求过来，直接返回，然后开启线程操作，修改结果集，供上层轮询调用，实现异步。         *         */        CacheManager cacheManager = CacheManager.getInstance();        String sessionID = "test_sessionid";        Integer random_num = new Random().nextInt();        System.out.println(random_num);        MyCache myCache = new MyCache(sessionID,random_num);        cacheManager.setCache(sessionID,myCache);        //休眠3秒        try {            Thread.sleep(1000*3);        } catch (InterruptedException e) {            e.printStackTrace();        }        System.out.println(cacheManager.getCache(sessionID).getCacheObj().toString());    }}