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一、案例要求

实例要求:

  1. 编写一个 NIO 群聊系统, 实现服务器端和客户端之间的数据简单通讯(非 阻塞)
  2. 实现多人群聊
  3. 服务器端: 可以监测用户上线, 离线,并实现消息转发功能
  4. 客户端: 通过channel 可以无阻塞发送消息给其它所有用户,同时可以接受 其它用户发送的消息(有服务器转发得到)
  5. 目的: 进一步理解NIO非阻塞网络编程机制

实现效果:

思路步骤:

  1. 先编写服务器端
    • 服务器启动并监听 6667
    • 服务器接收客户端信息,并实现转发 [处理上线和离线]
  2. 编写客户端
    • 连接服务器
    • 发送消息
    • 接收服务器消息

二、服务器端

public class GroupChatServer {

    //定义属性
    private Selector selector;
    private ServerSocketChannel listenChannel;
    private static final int PORT = 6667;

    //构造器
    //初始化工作
    public GroupChatServer() {

        try {

            //得到选择器
            selector = Selector.open();
            System.out.println("selector = " + selector);

            //获取 ServerSocketChannel
            listenChannel = ServerSocketChannel.open();
            //绑定端口
            listenChannel.socket().bind(new InetSocketAddress(PORT));
            //设置非阻塞模式
            listenChannel.configureBlocking(false);
            //将该 listenChannel 注册到selector
            listenChannel.register(selector, SelectionKey.OP_ACCEPT);

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

    //服务器监听
    public void listen() {
        System.out.println("监听线程: " + Thread.currentThread().getName());

        try {

            //循环处理
            while (true) {
                int count = selector.select();
                //有事件需要处理
                if (count > 0) {

                    //遍历得到的 selectionKey 集合
                    Iterator<SelectionKey> keyIterator = selector.selectedKeys().iterator();
                    while (keyIterator.hasNext()) {

                        //取出 SelectionKey
                        SelectionKey key = keyIterator.next();

                        //监听到accept
                        if (key.isAcceptable()) {
                            //创建一个SocketChannel
                            SocketChannel socketChannel = listenChannel.accept();
                            //设置非阻塞模式
                            socketChannel.configureBlocking(false);
                            //注册到选择器
                            socketChannel.register(selector, SelectionKey.OP_READ);

                            //提示
                            System.out.println(socketChannel.getRemoteAddress() + " 上线");

                        }

                        //通道发送read事件,即通道是可读的状态
                        if (key.isReadable()) {
                            //处理读(专门写方法...)
                            read(key);
                        }

                        //当前的key 删除,防止重复处理
                        keyIterator.remove();
                    }

                } else {
                    System.out.println("等待...");
                }
            }


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

    //读取客户端信息
    private void read(SelectionKey key) {
        //得到关联的 Channel
        SocketChannel socketChannel = null;

        try {
            //得到 channel
            socketChannel = (SocketChannel) key.channel();
            //创建 buffer
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            //读取数据
            int count = socketChannel.read(buffer);
            //根据 count 的值去做处理
            if (count > 0) {
                //把缓存区的数据转成字符串
                String msg = new String(buffer.array());
                //输出该消息
                System.out.println("form 客户端:" + msg);

                //转发消息:向其它的客户端转发消息(去掉自己), 专门写一个方法来处理
                sentInfoToOtherClients(msg, socketChannel);
            }
        }catch (IOException e) {
            try {
                System.out.println(socketChannel.getRemoteAddress() + " 离线了..");
                //取消注册
                key.cancel();
                //关闭通道
                socketChannel.close();
            } catch (IOException e2) {
                e2.printStackTrace();
            }
        }
    }

    //转发消息给其它客户(通道)
    private void sentInfoToOtherClients(String msg, SocketChannel self) throws IOException{
        System.out.println("服务器转发消息中...");
        System.out.println("服务器转发数据给客户端线程: " + Thread.currentThread().getName());

        //遍历 所有注册到selector 上的 SocketChannel,并排除 self
        for (SelectionKey key : selector.keys()) {

            //通过 key 获取到对应的 channel
            Channel targetChannel = key.channel();

            //排除自己
            if (targetChannel instanceof SocketChannel && targetChannel != self) {
                //转型
                SocketChannel dest = (SocketChannel) targetChannel;
                //将msg存储到 buffer
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                //将 buffer 的数据写入通道
                dest.write(buffer);
            }
        }
    }


    public static void main(String[] args) {
        //创建服务器对象
        GroupChatServer groupChatServer = new GroupChatServer();
        groupChatServer.listen();
    }
}

三、客户端

public class GroupChatClient {

    //定义相关的属性
    // 服务器的ip
    private static final String HOST = "127.0.0.1";
    //服务器端口
    private static final Integer PORT = 6667;
    private Selector selector;
    private SocketChannel socketChannel;
    private String userName;

    //构造器,完成初始化工作
    public GroupChatClient() {
        try {
            //获取选择器
            selector = Selector.open();
            System.out.println("selector = " + selector);
            //连接服务器
            socketChannel = SocketChannel.open(new InetSocketAddress(HOST, PORT));
            //设置非阻塞
            socketChannel.configureBlocking(false);
            //将 socketChannel 注册到 selector
            socketChannel.register(selector, SelectionKey.OP_READ);
            //得到 userName
            userName = socketChannel.getLocalAddress().toString().substring(1);
            System.out.println(userName + " is ok...");

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

    //向服务器发送消息
    public void sendInfo(String info) {
        info = userName + "说:" + info;

        try {
            socketChannel.write(ByteBuffer.wrap(info.getBytes()));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //读取从服务器端回复的消息
    public void readInfo() {

        try {
            int readChannels = selector.select();
            //有可以用的通道
            if (readChannels > 0) {
                Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                while (iterator.hasNext()) {

                    SelectionKey key = iterator.next();
                    if (key.isReadable()) {
                        //得到相关的通道
                        SocketChannel socketChannel = (SocketChannel) key.channel();
                        //得到一个 Buffer
                        ByteBuffer buffer = ByteBuffer.allocate(1024);
                        //读取
                        socketChannel.read(buffer);
                        //把读到的缓冲区的数据转成字符串
                        String msg = new String(buffer.array());
                        System.out.println(msg.trim());
                    }
                }

                //删除当前的selectionKey, 防止重复操作
                iterator.remove();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    public static void main(String[] args) {
        //启动客户端
        GroupChatClient chatClient = new GroupChatClient();


        //启动一个线程,每隔3秒,读取从服务器发送的数据
        new Thread() {
            @Override
            public void run() {
                System.out.println("读取信息");
                chatClient.readInfo();
                try {
                    Thread.sleep(3000);
                } 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();
            chatClient.sendInfo(s);
        }
    }
}

 

posted on   格物致知_Tony  阅读(54)  评论(0编辑  收藏  举报
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