java NIO实现简单聊天程序

public class Server {

    private Selector selector;
    private ByteBuffer writeBuffer = ByteBuffer.allocate(1024);
    private ByteBuffer readBuffer = ByteBuffer.allocate(1024);
    Msg msg = new Msg();
    MsgSender msgSender = new MsgSender(msg);
    public static void main(String[] args) {
        Server server = new Server();
        new Thread(server.msgSender).start();
        server.start();

    }

    //初始化服务端
    public Server() {
        try {
            this.selector = Selector.open();
            ServerSocketChannel ssc = ServerSocketChannel.open();
            ssc.configureBlocking(false);
            ssc.bind(new InetSocketAddress(8899));
            ssc.register(this.selector, SelectionKey.OP_ACCEPT);
            System.out.println("服务端初始化完毕。。。。");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //启动服务端等待selector事件
    public void start() {
        while (true) {
            try {
                int num = this.selector.select();
                if (num > 0) {
                    Iterator<SelectionKey> it = this.selector.selectedKeys().iterator();
                    while (it.hasNext()) {
                        SelectionKey key = it.next();
                        it.remove();
                        if (key.isValid()) {
                            if (key.isAcceptable()) {
                                this.accept(key);
                            }
                            if (key.isReadable()) {
                                this.read(key);
                            }
                            if (key.isWritable()) {
                                this.write(key);
                            }
                        }
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    //发送消息
    private void write(SelectionKey key) {
        SocketChannel sc = (SocketChannel) key.channel();
        try {
            sc.configureBlocking(false);
        } catch (IOException e) {
            e.printStackTrace();
        }
  //判断是否有消息需要发送
        if(msg!=null && msg.getFlag()){
            System.out.println(msg);
            try {
                msg.setFlag(false);
                writeBuffer.clear();
                writeBuffer.put(msg.getContent().getBytes());
                writeBuffer.flip();
                sc.write(writeBuffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }


    }

    //读取客户端消息
    private void read(SelectionKey key) {
        SocketChannel sc = (SocketChannel) key.channel();
        try {
            sc.configureBlocking(false);
            readBuffer.clear();
            int read = sc.read(readBuffer);
            if (read == -1) {
                sc.close();
                key.cancel();
            }
            readBuffer.flip();
            System.out.println(new String(readBuffer.array()));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //接受客户端连接
    private void accept(SelectionKey key) {
        ServerSocketChannel ssc = (ServerSocketChannel) key.channel();
        try {
            SocketChannel sc = ssc.accept();
            System.out.println(String.format("a new client join!!!host:%s;port:%d", sc.socket().getLocalAddress(), sc.socket().getPort()));
            sc.configureBlocking(false);
            sc.register(this.selector, SelectionKey.OP_READ | SelectionKey.OP_WRITE);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

class Msg {
    private Boolean flag=false;
    private String content;

    public Boolean getFlag() {
        return flag;
    }

    public void setFlag(Boolean flag) {
        this.flag = flag;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    @Override
    public String toString() {
        return "Msg{" +
                "flag=" + flag +
                ", content='" + content + '\'' +
                '}';
    }
}

class MsgSender implements Runnable{
    private Msg msg;

    public MsgSender(Msg msg) {
        this.msg = msg;
    }

    @Override
    public void run() {
        while (true) {
            System.out.println("input:\n");
            Scanner scanner = new Scanner(System.in);
            this.msg.setContent(scanner.next());
            this.msg.setFlag(true);
        }
    }
}

public class Client {
    private SocketChannel sc;
    ByteBuffer writeBuffer = ByteBuffer.allocate(1024);
    ByteBuffer readBuffer = ByteBuffer.allocate(1024);

    public static void main(String[] args) {
        new Client();
    }
    public Client() {
        try {
            sc = SocketChannel.open();
            //连接服务端
            sc.connect(new InetSocketAddress(8899));
            //发送消息
            this.write(sc);
            //读取消息
            this.read(sc);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void read(SocketChannel sc) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    try {
                        readBuffer.clear();
                        int read = sc.read(readBuffer);
                        readBuffer.flip();
                        System.out.println(new String(readBuffer.array()));
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }

    private void write(SocketChannel sc) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    Scanner scanner = new Scanner(System.in);
                    String next = scanner.next();
                    writeBuffer.clear();
                    writeBuffer.put(next.getBytes());
                    writeBuffer.flip();
                    try {
                        sc.write(writeBuffer);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }
}