while (true) {
    int selectKey = selector.select();
    if (selectKey > 0) {
        Set<SelectionKey> keySet = selector.selectedKeys();
        Iterator<SelectionKey> iter = keySet.iterator();
        //对selectionkey进行遍历
        while (iter.hasNext()) {
            SelectionKey selectionKey = iter.next();

            //读事件，处理数据读取
            if (selectionKey.isReadable()) {
                System.out.println("======read======");
                read(selectionKey);
            }

        }
    }
}