（八）AIO聊天室实战

1.AIO模型分析

• AsyncChannelGroup指的是，可以被多个异同通道所共享的资源群组。其中，最主要的资源有线程池。
• 不指定的情况下，系统会使用一个默认的AsyncChannelGroup。
• 在AIO编程模型中，高效率和方便是因为操作系统做了很多的事。
• 在请求处理的过程中，并不是在主线程中完成的，而是通道组利用线程池资源，在不同的线程中完成异步处理。

2.实验结果

 

 

3.完整代码

   3.1服务器端

public class ChatServer {

    private static final String LOCALHOST = "localhost";
    private static final int DEFAULT_PORT = 8888;
    private static final String QUIT = "quit";
    private static final int BUFFER = 1024;
    private static final int THREADPOOL_SIZE = 8;

    private AsynchronousChannelGroup channelGroup; // 自定义Group
    private AsynchronousServerSocketChannel serverChannel;
    private List<ClientHandler> connectedClients;
    private Charset charset = Charset.forName("UTF-8");
    private int port;

    public ChatServer() {
        this(DEFAULT_PORT);
    }

    public ChatServer(int port) {
        this.port = port;
        this.connectedClients = new ArrayList<>();
    }
    private boolean readyToQuit(String msg) {
        return QUIT.equals(msg);
    }
    private void close(Closeable closeable) {
        if (closeable != null) {
            try {
                closeable.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    // 获取客户端的端口号并打印出来
    private String getClientName(AsynchronousSocketChannel clientChannel) {
        int port = -1;
        try {
            InetSocketAddress remoteAddress = (InetSocketAddress) clientChannel.getRemoteAddress();
            port = remoteAddress.getPort();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "客户端[" + port + "]";
    }


    // 添加和移除用户操作，记得用synchronized修饰
    private synchronized void addClient(ClientHandler clientHandler) {
        connectedClients.add(clientHandler);
        System.out.println(getClientName(clientHandler.getClientChannel()) + "已连接");

    }
    private synchronized void removeClient(ClientHandler clientHandler) {
        connectedClients.remove(clientHandler);
        AsynchronousSocketChannel clientChannel = clientHandler.getClientChannel();
        System.out.println(getClientName(clientChannel) + "已断开连接");
        close(clientChannel);
    }

    // 转发和接收
    private synchronized String receive(ByteBuffer buffer) {
        return String.valueOf(charset.decode(buffer));
    }
    private synchronized void forwardMessage(AsynchronousSocketChannel clientChannel, String fwdMsg) {
        for (ClientHandler connectedHandler : connectedClients) {
            AsynchronousSocketChannel client = connectedHandler.getClientChannel();
            if (!client.equals(clientChannel)) {
                // 注意这个try-catch是自己加的，避免因写操作问题而引发服务器宕dang机
                try {
                    // 将要转发的信息写入到缓冲区中
                    ByteBuffer buffer = charset.encode(getClientName(client) + ": " + fwdMsg);
//                    ByteBuffer buffer = ByteBuffer.allocate(BUFFER);
//                    buffer.put(charset.encode(getClientName(client) + ": " + fwdMsg));
//                    buffer.flip();
                    // 写给其他客户
                    client.write(buffer, null, connectedHandler);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }

    private void start() {

        try {
            // 创建自定义Group
            ExecutorService executorService = Executors.newFixedThreadPool(THREADPOOL_SIZE); // 创建固定数量的线程池
            channelGroup = AsynchronousChannelGroup.withThreadPool(executorService);
            // 创建AsynchronousServerSocketChannel，绑定服务端监听端口
            serverChannel = AsynchronousServerSocketChannel.open(channelGroup); // 传入自定义的Group
            serverChannel.bind(new InetSocketAddress(LOCALHOST, port));
            System.out.println("启动服务器，监听端口：" + port + "...");

            // 持续监听客户端的连接请求，如果不加循环，第一次异步调用accept后，还没等到回调函数，系统就退出了
            while (true) {
                serverChannel.accept(null, new AcceptHandler()); // 使用AcceptHandler()的回调函数异步处理accept()
                // 因为不想浪费资源，过于频繁的调用accept
                // 希望通过AcceptHandler的回调函数来进一步持续监听从客户端发来的请求
                System.in.read(); // 阻塞，等待System.in流上的输入数据
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            close(serverChannel);
        }
    }

    // CompletionHandler接口泛型的类型，第一个表示异步调用函数应该返回的类型，即accept()返回结果的类型
    // 第二个泛型类型指的是，attachment对象的类型
    private class AcceptHandler implements CompletionHandler<AsynchronousSocketChannel,Object> {

        @Override
        public void completed(AsynchronousSocketChannel clientChannel, Object attachment) {
            if (serverChannel.isOpen()) {
                serverChannel.accept(null, this); // 让服务器接着等待下一个客户端的连接
            }
            // 接收本次连接的客户端所发送的消息
            if (clientChannel != null && clientChannel.isOpen()) {
                ClientHandler handler = new ClientHandler(clientChannel); // handler处理特定的clientChannel
                // 通过Buffer实现和Channel之间的数据交互
                ByteBuffer buffer = ByteBuffer.allocate(BUFFER);
                // 将新用户添加到在线用户列表
                addClient(handler);

                // 第一个buffer参数：读取channel数据写入buffer里； 第二个buffer参数：把buffer当做attachment
                // read()返回的数据类型是Integer，表示从channel中读到了多少数据。
                // 如果在回调函数想要得到具体的数据内容是什么，把buffer当做attachment，因为attachment会作为参数传递到回调函数
                clientChannel.read(buffer,buffer, handler);
            }
        }

        @Override
        public void failed(Throwable exc, Object attachment) {
            System.out.println("连接失败: " + exc.getMessage());
        }
    }

    // 处理在clientChannel上的异步读写操作的结果
    private class ClientHandler implements CompletionHandler<Integer,Object>{
        private AsynchronousSocketChannel clientChannel;
        public ClientHandler(AsynchronousSocketChannel clientChannel) {
            this.clientChannel = clientChannel;
        }

        public AsynchronousSocketChannel getClientChannel() {
            return clientChannel;
        }

        @Override
        public void completed(Integer result, Object attachment) {
            // 判断完成的是read操作还是write操作，如果是read操作，attachment对象就是包含客户端数据的buffer
            ByteBuffer buffer = (ByteBuffer) attachment;
            // 处理read()的异步调用
            if (buffer != null) {
                if (result <= 0) {
                    // 没有读到有效数据，客户端异常
                    // 将客户移除在线列表(列表里存放的是每个clientChannel对应的ClientHandler)
                    removeClient(this);
                }else {
                    buffer.flip(); // 写模式变为读模式
                    // buffer中是编码后的数据，把Byte解码成字符串
                    String fwdMsg = receive(buffer);
                    System.out.println(getClientName(clientChannel) + ": " + fwdMsg);

                    // 转发消息
                    forwardMessage(clientChannel, fwdMsg);
                    buffer.clear();

                    if (readyToQuit(fwdMsg)) {
                        removeClient(this);
                    }else {
                        clientChannel.read(buffer, buffer, this);
                    }
                }
            }
        }

        @Override
        public void failed(Throwable exc, Object attachment) {
            System.out.println("读写操作失败：" + exc.getMessage());
        }
    }

    public static void main(String[] args) {
        ChatServer server = new ChatServer();
        server.start();
    }
}

   3.2客户端

public class ChatClient {
    private static final String LOCAL_HOST = "localhost";
    private static final int DEFAULT_PORT = 8888;
    private static final String QUIT = "quit";
    private static final int BUFFER = 1024;

    private AsynchronousSocketChannel clientChannel;
    private Charset charset = Charset.forName("UTF-8");

    public boolean readyToQuit(String msg) {
        return QUIT.equals(msg);
    }

    public void close(Closeable closeable) {
        if (closeable != null) {
            try {
                closeable.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    // 向服务器发送消息
    public void send(String msg) throws ExecutionException, InterruptedException {
        if (msg.isEmpty()) {
            return;
        }
        ByteBuffer buffer = charset.encode(msg);
        Future<Integer> writeResult = clientChannel.write(buffer);
        writeResult.get();
    }

    private void start() {
        try {
            // 创建异步通道channel，并发起连接请求
            clientChannel = AsynchronousSocketChannel.open();
            Future<Void> future = clientChannel.connect(new InetSocketAddress(LOCAL_HOST, DEFAULT_PORT));

            future.get();  // 阻塞式调用，直到建立连接再进行下一步操作
            System.out.println("已连接到服务器");

            // 创建线程处理用户输入
            new Thread(new UserInputHandler(this)).start();

            // 主线程中循环读取服务器转发过来的其他客户的消息
            ByteBuffer buffer = ByteBuffer.allocate(BUFFER);
            while (true) {
                Future<Integer> readResult = clientChannel.read(buffer);
                int result = readResult.get(); // 阻塞式读取数据
                if (result <= 0) {
                    // 发生异常，没有读取到数据
                    close(clientChannel);
                    System.out.println("与服务器连接异常");
                    System.exit(1); // 停止程序，否则quit后，会出现报错
                }else {
                    // 正常打印消息
                    buffer.flip();
                    String msg = String.valueOf(charset.decode(buffer));
                    buffer.clear();
                    System.out.println(msg);
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        } finally {
            close(clientChannel);
        }
    }

    public static void main(String[] args) {
        ChatClient client = new ChatClient();
        client.start();
    }
}

public class UserInputHandler implements Runnable {
    private ChatClient client;

    public UserInputHandler(ChatClient chatClient) {
        this.client = chatClient;
    }

    @Override
    public void run() {
        BufferedReader consoleReader = new BufferedReader(new InputStreamReader(System.in));
        while (true) {
            try {
                String msg = consoleReader.readLine();
                client.send(msg);
                if (client.readyToQuit(msg)) {
                    System.out.println("成功推出聊天室");
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            } catch (InterruptedException e) {
                e.printStackTrace();
            } catch (ExecutionException e) {
                e.printStackTrace();
            }
        }
    }
}

参考

一站式学习Java网络编程 全面理解BIO_NIO_AIO，学习手记（八）