package com.xxx.common.utils;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

/**
 * 内存缓存管理 (单位分钟)
 * Created by xuyinglong on 16/10/1.
 */
public class CacheUtils {
    private static Map<String, Object> DICT             = new ConcurrentHashMap<String, Object>(20000);            // 数据字典
    private static Map<String, Long>   DICT_EXPIREDTIME = new ConcurrentHashMap<String, Long>(20000);    // 过期字典
    private static long                DEFAULT_MINUTE   = 15;    // 默认过期时间:15分钟

    /** 存 */
    public static boolean set(String key, Object obj) {
        return set(key, obj, DEFAULT_MINUTE);
    }

    /** 存, 指定过期时间 分钟 */
    public static boolean set(String key, Object obj, long minutes) {
        if (obj == null || key == null) return false;

        long time = System.currentTimeMillis() + minutes * 60 * 1000;
        DICT_EXPIREDTIME.put(key, time);
        DICT.put(key, obj);
        return true;
    }

    /** 存, 指定过期时间 分钟 */
    public static boolean set(String key, Object obj, double minutes) {
        if (obj == null || key == null) return false;

        long time = System.currentTimeMillis() + (long) (minutes * 60 * 1000);
        DICT_EXPIREDTIME.put(key, time);
        DICT.put(key, obj);
        return true;
    }

    /** 取 */
    public static Object get(String key) {
        Long time = DICT_EXPIREDTIME.get(key);
        if (time == null) return null;
        // 过期了
        if (time < System.currentTimeMillis()) {
            DICT_EXPIREDTIME.remove(key);
            DICT.remove(key);
            return null;
        }
        return DICT.get(key);
    }

    /** 删 */
    public static boolean delete(String key) {
        DICT_EXPIREDTIME.remove(key);
        DICT.remove(key);
        return true;
    }

    /** 状态:字典数量 */
    public static String status() {
        StringBuilder sb = new StringBuilder();
        sb.append("objects size:").append(DICT.size());
        return sb.toString();
    }

    /** 清理所有过期的内容(可定时任务清理) */
    public static int clearAllExpired() {
        int cnt = 0;
        long now = System.currentTimeMillis();
        Set<String> keys = DICT_EXPIREDTIME.keySet();
        for (String k : keys) {
            long time = DICT_EXPIREDTIME.get(k);
            if (time < now) {
                DICT_EXPIREDTIME.remove(k);
                DICT.remove(k);
                cnt++;
            }
        }
        return cnt;
    }

    /** 清理所有 */
    public static boolean clearAll() {
        DICT_EXPIREDTIME.clear();
        DICT.clear();
        return true;
    }

    /** 是否存在对象 */
    public static boolean exists(String key) {
        return get(key) != null;
    }

    public static void main(String[] args) {
        String key = "hello";
        CacheUtils.set(key, null);

        System.out.println(CacheUtils.get(key));
    }
}