基于java NIO 的服务端与客户端代码

在对java NIO  selector 与 Buffer Channel  有一定的了解之后，我们进行编写java nio 实现的 客户端与服务端例子：

服务端：

public class NIOChatService {

    private static Map<String,SocketChannel> userMap =new HashMap<>();
    public static void main(String[] args) throws Exception {

        //创建selector 对象
        Selector selector =Selector.open();
        //创建serverSocketChannel
        ServerSocketChannel serverSocketChannel =ServerSocketChannel.open();
        //设置为非阻塞
        serverSocketChannel.configureBlocking(false);
        //绑定端口
        serverSocketChannel.bind(new InetSocketAddress(9999));
        //监听客户端的连接事件，绑定在selector 上
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
        //死循环
        while(true) {

            //阻塞监听，监听是否有事件发生
            selector.select();
            //获取事件发生的selectionkey
            Set<SelectionKey>     selectedKeys = selector.selectedKeys();

            for(SelectionKey key:selectedKeys) {
                if(key.isAcceptable()) {
                //如果是客户端的连接的话
                ServerSocketChannel serverchannel=(ServerSocketChannel)key.channel();
                //获取socketchannel 传输对象
                SocketChannel accept = serverchannel.accept();
                accept.configureBlocking(false);
                accept.register(selector, SelectionKey.OP_READ);
                //保存连接的用户信息
                String keys ="{"+UUID.randomUUID()+"}";
                userMap.put(keys, accept);
                System.out.println(userMap);
            }

                else if(key.isReadable()) {
                    //只要能进入到可读的，那么channel 一定是SocketChannel
                    SocketChannel socketChannel =(SocketChannel)key.channel();

                    ByteBuffer bytebuffer =ByteBuffer.allocate(1024);

                    //读取数据到ByteBuffer

                    socketChannel.read(bytebuffer);

                    bytebuffer.flip();
                    Charset charset =Charset.forName("utf-8");
                    String receiveMsg=String.valueOf(charset.decode(bytebuffer).array());

                    for(Map.Entry<String, SocketChannel> entry:userMap.entrySet()) {

                        ByteBuffer bys1 =ByteBuffer.allocate(1024);
                        bys1.put((entry.getKey()+receiveMsg).getBytes());
                        SocketChannel channel =entry.getValue();
                        bys1.flip();
                        channel.write(bys1);

                    }

                }
                //一定要进行clear 操作
                selectedKeys.clear();
            }

            ;

        }

    }

}

客户端例子：

public class JavaNioClient {

    public static void main(String[] args) throws Exception {

        //建立Selector
        Selector selector =Selector.open();
        SocketChannel socketChannel=SocketChannel.open();
        //设置非阻塞
        socketChannel.configureBlocking(false);

        socketChannel.register(selector, SelectionKey.OP_CONNECT);

        socketChannel.connect(new InetSocketAddress("127.0.0.1", 9999));

        while(true) {
            selector.select();

            Set<SelectionKey> setionkey =selector.selectedKeys();

            for(SelectionKey kk :setionkey) {
                if(kk.isConnectable()) {
                    //从selectionkey 获取socketChannel
                    SocketChannel socket=(SocketChannel)kk.channel();
                    //手动建立连接
                    if(socket.isConnectionPending()) {
                        socket.finishConnect();
                        //写数据
                        ByteBuffer byteB = ByteBuffer.allocate(1024);
                        byteB.put((System.currentTimeMillis()+"连接ok").getBytes());
                        byteB.flip();
                        socket.write(byteB);
                        //jdk1.5 线程池
                        ExecutorService exe =Executors.newSingleThreadExecutor(Executors.defaultThreadFactory());

                        exe.submit(new Thread() {

                            @Override
                            public void run() {
                                while(true) {
                                    String msg=null;
                                byteB.clear();
                                //标准键盘输入
                                BufferedReader br =new BufferedReader(new InputStreamReader(System.in));
                                try {
                                     msg =br.readLine();
                                     ByteBuffer bytec = ByteBuffer.allocate(1024);
                                     bytec.put(msg.getBytes());
                                     bytec.flip();
                                     socket.write(bytec);
                                } catch (IOException e) {

                                    e.printStackTrace();
                                }
                                }
                            }
                        });
                    }

                    socket.register(selector, SelectionKey.OP_READ);
                }
                else if(kk.isReadable())  {

                    //从selectionkey 获取socketChannel
                    SocketChannel socket=(SocketChannel)kk.channel();
                    ByteBuffer by =ByteBuffer.allocate(1024);
                    int a=socket.read(by);
                    //if(a>0) {
                    String receive =new String(by.array());
                    System.out.println(receive);
                    //}
                }

                setionkey.clear();
            }

        }

    }

}