Callable 對象 Future異步計算 統計結果

        ExecutorService pool = Executors.newFixedThreadPool(MAX_THREAD_CNT);

        Map<DBNeInfo, String> resultMap = new HashMap<DBNeInfo, String>();

        List<Future<Map<DBNeInfo, String>>> futures = new ArrayList<Future<Map<DBNeInfo, String>>>();

        try
        {
            //併發執行任務
            for (DBNeInfo ne : nelist)
            {
                futures.add(pool.submit(new UpdatDnsTask(ne, dnsIp, dnsIpBak)));
            }
        }
        finally
        {
            pool.shutdown();
        }

        //獲取返回結果
        for (Future<Map<DBNeInfo, String>> future : futures)
        {
            try
            {
                Map<DBNeInfo, String> map = future.get();
                if ((null != map) && !map.isEmpty())
                {
                    resultMap.putAll(map);
                }
            }
            catch (InterruptedException e)
            {
                logger.error("updateDnsToNe InterruptedException", e);
            }
            catch (ExecutionException e)
            {
                logger.error("updateDnsToNe ExecutionException", e);
            }
        }

        logger.debug("syncNeFromSLBs end");

        return resultMap;

 /**
     * 併發更新dns任務
     */
    private class UpdatDnsTask implements Callable<Map<DBNeInfo, String>>
    {
        /**
         * ip地址
         */
        private final DBNeInfo ne;

        private final String dnsIp;

        private final String dnsIpBak;

        /**
         * 構造函數
         * 
         * @param ip 同步網元的IP地址
         * @param isAddSelf 是否返回本身的網元信息
         * @throws CDNException 異常信息
         */
        public UpdatDnsTask(final DBNeInfo ne, final String dnsIp, final String dnsIpBak) throws CDNException
        {
            if (ne == null)
            {
                throw new CDNException("ne is null");
            }
            this.ne = ne;
            this.dnsIp = dnsIp;
            this.dnsIpBak = dnsIpBak;
        }

        @Override
        public Map<DBNeInfo, String> call() throws CDNException
        {
            return updateDns(ne, dnsIp, dnsIpBak);
        }}

Callable 返回計算結果，可以拋出異常，Runnable 不能返回結果，不能拋出異常。