NIO编程实现

       //1.创建selector
        Selector selector = Selector.open();
        //2.通过serverSocketChannel创建channel
        ServerSocketChannel channel = ServerSocketChannel.open();
        //3.为channel通道绑定监听端口
        channel.bind(new InetSocketAddress(8000));
        //4.设置channel为非阻塞模式
        channel.configureBlocking(false);
        //5.将channel注册到selector上，监听连接事件
        channel.register(selector, SelectionKey.OP_ACCEPT);
        System.out.println("服务器启动");
        //6.调用selectKeys方法获取就绪channel集合

       //7.判断就绪事件种类，调用业务处理方法

      // 8.根据业务需要决定是否再次注册监听事件，重复执行第三步操作。
        //循环等待新接入的连接
        for(;;){
            int select = selector.select();
            if(select==0){
                continue;
            }
            Set<SelectionKey> selectionKeys = selector.selectedKeys();
            Iterator<SelectionKey> iterator = selectionKeys.iterator();
            while (iterator.hasNext()){
                SelectionKey selectionKey = iterator.next();
                //移除set中的当期selectionKey
                iterator.remove();
                //分状态进行处理
                if(selectionKey.isAcceptable()){
                    acceptHandler(channel,selector);
                }
                //处理可读
                if(selectionKey.isReadable()){
                    readHandler(selectionKey,selector);
                }
            }
        }