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 ;
            }
        }
        //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 = ; 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 <= ||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 = ;
            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) != -) { //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) != -) {
                        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(); 

        }
    }