Java中memcached 如何获取所有未过期的key？

Question

Java中memcached 如何获取所有未过期的key？下面写了一个获取所有key的方法，但是会得到过期的key，如何过滤掉？

public static List<String> getAllKey(String reg) {
        List<String> keylist = new ArrayList<String>();
        Map<String, Map<String, String>> statsItems = memcachedClient.statsItems(); //获取所有items
        Map<String, String> statsItems_sub = null;
        String server = null;
        String statsItems_sub_key = null;
        int items_number = 0;

        Map<String, Map<String, String>> statsCacheDump = null;
        Map<String, String> statsCacheDump_sub = null;
        String statsCacheDumpsub_key = null;
        for (Iterator<String> iterator = statsItems.keySet().iterator(); iterator.hasNext(); ) {
            server = iterator.next(); //server地址
            keylist.add(server);
            statsItems_sub = statsItems.get(server);
            for (Iterator<String> iterator_item = statsItems_sub.keySet().iterator(); iterator_item.hasNext(); ) {
                statsItems_sub_key = iterator_item.next();
                if (statsItems_sub_key.toUpperCase().startsWith("items:".toUpperCase()) && statsItems_sub_key.toUpperCase().endsWith(":number".toUpperCase())) {
                    items_number = Integer.parseInt(statsItems_sub.get(statsItems_sub_key).trim());
                    statsCacheDump = memcachedClient.statsCacheDump(new String[]{server}, Integer.parseInt(statsItems_sub_key.split(":")[1].trim()), items_number); //获取一个item
                    for (Iterator<String> statsCacheDump_iterator = statsCacheDump.keySet().iterator(); statsCacheDump_iterator.hasNext(); ) {
                        statsCacheDump_sub = statsCacheDump.get(statsCacheDump_iterator.next());
                        for (Iterator<String> iterator_keys = statsCacheDump_sub.keySet().iterator(); iterator_keys.hasNext(); ) {
                            statsCacheDumpsub_key = (String) iterator_keys.next(); //获取item的key
                            if(statsCacheDumpsub_key.contains(reg)){
                                keylist.add(statsCacheDumpsub_key);
                            }
                        }
                    }
                }
            }
        }
        return keylist;
    }