HashMap实现缓存（二）

    package com.cache; 
     
    import java.util.*; 
     
     //Description: 管理缓存 
     
     //可扩展的功能：当chche到内存溢出时必须清除掉最早期的一些缓存对象，这就要求对每个缓存对象保存创建时间 
     
    public class CacheManager { 
        private static HashMap cacheMap = new HashMap(); 
     
        //单实例构造方法 
        private CacheManager() { 
            super(); 
        } 
        //获取布尔值的缓存 
        public static boolean getSimpleFlag(String key){ 
            try{ 
                return (Boolean) cacheMap.get(key); 
            }catch(NullPointerException e){ 
                return false; 
            } 
        } 
        public static long getServerStartdt(String key){ 
            try { 
                return (Long)cacheMap.get(key); 
            } catch (Exception ex) { 
                return 0; 
            } 
        } 
        //设置布尔值的缓存 
        public synchronized static boolean setSimpleFlag(String key,boolean flag){ 
            if (flag && getSimpleFlag(key)) {//假如为真不允许被覆盖 
                return false; 
            }else{ 
                cacheMap.put(key, flag); 
                return true; 
            } 
        } 
        public synchronized static boolean setSimpleFlag(String key,long serverbegrundt){ 
            if (cacheMap.get(key) == null) { 
                cacheMap.put(key,serverbegrundt); 
                return true; 
            }else{ 
                return false; 
            } 
        } 
     
     
        //得到缓存。同步静态方法 
        private synchronized static Cache getCache(String key) { 
            return (Cache) cacheMap.get(key); 
        } 
     
        //判断是否存在一个缓存 
        private synchronized static boolean hasCache(String key) { 
            return cacheMap.containsKey(key); 
        } 
     
        //清除所有缓存 
        public synchronized static void clearAll() { 
            cacheMap.clear(); 
        } 
     
        //清除某一类特定缓存,通过遍历HASHMAP下的所有对象，来判断它的KEY与传入的TYPE是否匹配 
        public synchronized static void clearAll(String type) { 
            Iterator i = cacheMap.entrySet().iterator(); 
            String key; 
            ArrayList arr = new ArrayList(); 
            try { 
                while (i.hasNext()) { 
                    java.util.Map.Entry entry = (java.util.Map.Entry) i.next(); 
                    key = (String) entry.getKey(); 
                    if (key.startsWith(type)) { //如果匹配则删除掉 
                        arr.add(key); 
                    } 
                } 
                for (int k = 0; k < arr.size(); k++) { 
                    clearOnly(arr.get(k)); 
                } 
            } catch (Exception ex) { 
                ex.printStackTrace(); 
            } 
        } 
     
        //清除指定的缓存 
        public synchronized static void clearOnly(String key) { 
            cacheMap.remove(key); 
        } 
     
        //载入缓存 
        public synchronized static void putCache(String key, Cache obj) { 
            cacheMap.put(key, obj); 
        } 
     
        //获取缓存信息 
        public static Cache getCacheInfo(String key) { 
     
            if (hasCache(key)) { 
                Cache cache = getCache(key); 
                if (cacheExpired(cache)) { //调用判断是否终止方法 
                    cache.setExpired(true); 
                } 
                return cache; 
            }else 
                return null; 
        } 
     
        //载入缓存信息 
        public static void putCacheInfo(String key, Cache obj, long dt,boolean expired) { 
            Cache cache = new Cache(); 
            cache.setKey(key); 
            cache.setTimeOut(dt + System.currentTimeMillis()); //设置多久后更新缓存 
            cache.setValue(obj); 
            cache.setExpired(expired); //缓存默认载入时，终止状态为FALSE 
            cacheMap.put(key, cache); 
        } 
        //重写载入缓存信息方法 
        public static void putCacheInfo(String key,Cache obj,long dt){ 
            Cache cache = new Cache(); 
            cache.setKey(key); 
            cache.setTimeOut(dt+System.currentTimeMillis()); 
            cache.setValue(obj); 
            cache.setExpired(false); 
            cacheMap.put(key,cache); 
        } 
     
        //判断缓存是否终止 
        public static boolean cacheExpired(Cache cache) { 
            if (null == cache) { //传入的缓存不存在 
                return false; 
            } 
            long nowDt = System.currentTimeMillis(); //系统当前的毫秒数 
            long cacheDt = cache.getTimeOut(); //缓存内的过期毫秒数 
            if (cacheDt <= 0||cacheDt>nowDt) { //过期时间小于等于零时,或者过期时间大于当前时间时，则为FALSE 
                return false; 
            } else { //大于过期时间 即过期 
                return true; 
            } 
        } 
     
        //获取缓存中的大小 
        public static int getCacheSize() { 
            return cacheMap.size(); 
        } 
     
        //获取指定的类型的大小 
        public static int getCacheSize(String type) { 
            int k = 0; 
            Iterator i = cacheMap.entrySet().iterator(); 
            String key; 
            try { 
                while (i.hasNext()) { 
                    java.util.Map.Entry entry = (java.util.Map.Entry) i.next(); 
                    key = (String) entry.getKey(); 
                    if (key.indexOf(type) != -1) { //如果匹配则删除掉 
                        k++; 
                    } 
                } 
            } catch (Exception ex) { 
                ex.printStackTrace(); 
            } 
     
            return k; 
        } 
     
        //获取缓存对象中的所有键值名称 
        public static ArrayList getCacheAllkey() { 
            ArrayList a = new ArrayList(); 
            try { 
                Iterator i = cacheMap.entrySet().iterator(); 
                while (i.hasNext()) { 
                    java.util.Map.Entry entry = (java.util.Map.Entry) i.next(); 
                    a.add((String) entry.getKey()); 
                } 
            } catch (Exception ex) {} finally { 
                return a; 
            } 
        } 
     
        //获取缓存对象中指定类型 的键值名称 
        public static ArrayList getCacheListkey(String type) { 
            ArrayList a = new ArrayList(); 
            String key; 
            try { 
                Iterator i = cacheMap.entrySet().iterator(); 
                while (i.hasNext()) { 
                    java.util.Map.Entry entry = (java.util.Map.Entry) i.next(); 
                    key = (String) entry.getKey(); 
                    if (key.indexOf(type) != -1) { 
                        a.add(key); 
                    } 
                } 
            } catch (Exception ex) {} finally { 
                return a; 
            } 
        } 
     
    } 
     
     
    package com.cache; 
     
    public class Cache { 
            private String key;//缓存ID 
            private Object value;//缓存数据 
            private long timeOut;//更新时间 
            private boolean expired; //是否终止 
            public Cache() { 
                    super(); 
            } 
     
            public Cache(String key, Object value, long timeOut, boolean expired) { 
                    this.key = key; 
                    this.value = value; 
                    this.timeOut = timeOut; 
                    this.expired = expired; 
            } 
     
            public String getKey() { 
                    return key; 
            } 
     
            public long getTimeOut() { 
                    return timeOut; 
            } 
     
            public Object getValue() { 
                    return value; 
            } 
     
            public void setKey(String string) { 
                    key = string; 
            } 
     
            public void setTimeOut(long l) { 
                    timeOut = l; 
            } 
     
            public void setValue(Object object) { 
                    value = object; 
            } 
     
            public boolean isExpired() { 
                    return expired; 
            } 
     
            public void setExpired(boolean b) { 
                    expired = b; 
            } 
    } 
     
    //测试类， 
    class Test { 
        public static void main(String[] args) { 
            System.out.println(CacheManager.getSimpleFlag("alksd")); 
    //        CacheManager.putCache("abc", new Cache()); 
    //        CacheManager.putCache("def", new Cache()); 
    //        CacheManager.putCache("ccc", new Cache()); 
    //        CacheManager.clearOnly(""); 
    //        Cache c = new Cache(); 
    //        for (int i = 0; i < 10; i++) { 
    //            CacheManager.putCache("" + i, c); 
    //        } 
    //        CacheManager.putCache("aaaaaaaa", c); 
    //        CacheManager.putCache("abchcy;alskd", c); 
    //        CacheManager.putCache("cccccccc", c); 
    //        CacheManager.putCache("abcoqiwhcy", c); 
    //        System.out.println("删除前的大小："+CacheManager.getCacheSize()); 
    //        CacheManager.getCacheAllkey(); 
    //        CacheManager.clearAll("aaaa"); 
    //        System.out.println("删除后的大小："+CacheManager.getCacheSize()); 
    //        CacheManager.getCacheAllkey(); 
     
     
        } 
    }