基于NIO的群聊系统

客户端

public class NIOClient {
    /**
     * 1、连接服务器
     * 2、发消息 收消息
     */
    //定义属性
    private final String host = "127.0.0.1"; //服务器ip
    private final int port = 6667; //端口
    private Selector selector;
    private SocketChannel socketChannel;
    private String username;

    //构造器
    public NIOClient(){
        //完成初始化工作
        try {
            selector = selector.open();
            //连接服务器
            socketChannel = socketChannel.open(new InetSocketAddress(host,port));
            socketChannel.configureBlocking(false);
            socketChannel.register(selector, SelectionKey.OP_READ);
            //得到username
            username = socketChannel.getLocalAddress().toString().substring(1);
            System.out.println(username + " *** 客户端初始化完成");
        } catch (IOException e) {
            e.printStackTrace();
        }


    }
    //发送消息
    private void sendMsg(String msg){
        msg = username + "说： " + msg;

        try {
            socketChannel.write(ByteBuffer.wrap(msg.getBytes()));

        }catch (Exception e){
            e.printStackTrace();
        }

    }

    //读取从服务器端回复的消息
    private void readMsg(){
        try {
            int read = selector.select(1000);
            if (read >0) {
                //有可用通道
                Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                while (iterator.hasNext()){
                    SelectionKey key = iterator.next();
                    if (key.isReadable()) {
                        SocketChannel channel = (SocketChannel) key.channel();
                        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
                        channel.read(byteBuffer);
                        String info = new String(byteBuffer.array());
                        System.out.println("* " + info.trim() +" *");
                    }
                }
                iterator.remove();
            }else {
//                System.out.println("没有可用的通道~");
            }
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {

        //启动客户端
        NIOClient client = new NIOClient();

        //启动线程
        new Thread(() -> {
            while (true) {
                client.readMsg();
                try {
                    Thread.currentThread().sleep(2000);
                } catch (InterruptedException e){
                    e.printStackTrace();
                }
            }
        }).start();

        //发送数据 给服务器
        Scanner scanner = new Scanner(System.in);

        while (scanner.hasNextLine()){
            String s = scanner.nextLine();
            client.sendMsg(s);
        }
    }
}

服务端

public class NIOServer {
    /**
     * 1、编写服务器端
     * 2、服务器启动并监听6667
     * 3、服务器接收客户端信息，并实现转发（处理上线和下线）
     * 4、编写客户端
     */
    private Selector selector;
    private ServerSocketChannel serverSocketChannel;
    private SocketChannel socketChannel;
    private static final int port = 6667;

    //构造
    public NIOServer(){
        //初始化的工作
        try {
            //得到选择器
            selector = Selector.open();
            //serverSocketChannel =
            serverSocketChannel = serverSocketChannel.open();
            //绑定端口
            serverSocketChannel.socket().bind(new InetSocketAddress(port));
            //设置非阻塞
            serverSocketChannel.configureBlocking(false);
            //将该serverSocketChannel 注册到selector上
            serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
        }catch (IOException e){
            e.printStackTrace();
        }
    }

    //监听
    public void listen(){
        try {
            //循环处理
            while (true) {
                int count = selector.selectNow();
                if (count > 0) {
                    //有事件处理
                    //遍历得到的selectionKey 集合
                    Iterator<SelectionKey> keyIterator = selector.selectedKeys().iterator();
                    while (keyIterator.hasNext()){
                        //取出key
                        SelectionKey key = keyIterator.next();
                        if (key.isAcceptable()) {
                            //处理连接
                            SocketChannel accept = serverSocketChannel.accept();

                            accept.configureBlocking(false);
                            //注册
                            accept.register(selector, SelectionKey.OP_READ);
                            //给出上线提示
                            System.out.println("上线 *****"+ accept.getRemoteAddress());
                        }

                        if (key.isReadable()) {
                            //通道发生可读事件了
                            readData(key);
                        }
                        //当前的key删除 防止重复处理
                        keyIterator.remove();
                    }
                }
            }
        }catch (IOException e){
            e.printStackTrace();
        }finally {

        }
    }

    //读取客户端消息

    private void readData(SelectionKey key){
        //定义一个socketChannel
        SocketChannel channel = null;
        try {
            //得到channel
            channel = (SocketChannel) key.channel();
            //创建缓冲buffer
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            //得到一个长度
            int count = channel.read(buffer);
            if (count > 0) {
                //把缓冲区转成字符串输出
                String msg = new String(buffer.array());
                System.out.println("form 客户端 " + msg.trim());

                //像其他的客户端转发消息
                sendInfoToOtherClients(msg, channel);
            }
        }catch (Exception e){
            try {
                System.out.println(channel.getRemoteAddress() + "离线了。。");
                //取消注册
                key.cancel();
                //关闭通道
                channel.close();
            } catch (IOException ioException) {
                ioException.printStackTrace();
            }
        }
    }
    //转发
    private void sendInfoToOtherClients(String msg, SocketChannel channel){

        System.out.println(" 服务器转发消息中~~");
        //遍历 所有注册到selectorChannel 上 socketChannel 排除自己
        selector.selectedKeys().forEach(key -> {
            //取出通道
            SocketChannel targetChannel = (SocketChannel) key.channel();
            //排除自己
            if (targetChannel instanceof SocketChannel && targetChannel != channel) {
                //转发
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                try {
                    targetChannel.write(buffer);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });


    }

    public static void main(String[] args) {

        NIOServer nioServer = new NIOServer();

        nioServer.listen();
    }
}