基于NIO的多客户端群聊

分析需求

服务端

• 监听客户端状态
• 保存客户端聊天记录
• 将客户端的信息分发给其他客户端 群聊

客户端

• 连接服务端
• 接受服务端分发的消息
• 发出消息

代码编写

代码里有详细的注释，这里我们主要是看一下编写步骤

服务端

---------------------初始化------------------------------
1.开启serversocket通道
2.开启选择器
3.设置非阻塞，注册任务
--------------------监听客户端-------------------

1.判断是否有连接
2.有链接打印用户上线日志
---------------读取客户端发送到信息---------------------

1.打开对应的通道
2.打印消息日志
3.分发消息给其他客户端

//服务端通道
    private ServerSocketChannel channel;
    // 多路复用选择器
    private Selector selector;

    public chatServer() {
        try {
            channel = ServerSocketChannel.open();
            selector = Selector.open();
            SocketAddress address = new InetSocketAddress(6666);
            channel.socket().bind(address);
            channel.configureBlocking(false);
            channel.register(selector, SelectionKey.OP_ACCEPT);

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

    // 监听客户端变化
    public void listenClient() throws Exception {
        System.out.println("服务端开始监听客户端变化");
        while (true) {
        //获取需要处理的事件
            int num = selector.select();
            if (num == 0) {
                continue;
            }
            Set<SelectionKey> set = selector.selectedKeys();
            Iterator<SelectionKey> iterator = set.iterator();
            while (iterator.hasNext()) {
                SelectionKey key = iterator.next();
                iterator.remove();
                if (key.isAcceptable()) {
                	//获取连接
                    SocketChannel Clientchannel = channel.accept();
                    //设置非阻塞
                    Clientchannel.configureBlocking(false);
                    //注册任务
                    Clientchannel.register(selector, SelectionKey.OP_READ);
                    //打印用户上线日志
                    System.out.println("用户：" + Clientchannel.socket().getRemoteSocketAddress() + "上线了");
                    continue;
                } else if (key.isReadable()) {
                    readData(key);
                }
            }
        }

    }
//读取信息
    public void readData(SelectionKey key) {
        SocketChannel channel = null;
        try {
            //获取当前的信道
            channel = (SocketChannel) key.channel();
            //创建缓冲区
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            int read = channel.read(buffer);
            //>0代表有可读取的内容
            if (read > 0) {
                String msg = "用户" + channel.socket().getRemoteSocketAddress() + ":" + new String(buffer.array());
                //打印信息
                System.out.println(msg);
                sendToOther(msg, channel);
            }
        } catch (Exception e) {
            System.out.println("用户：" + channel.socket().getRemoteSocketAddress() + "下线了");
            key.cancel();
            try {
                channel.close();
            } catch (Exception e1) {
                e1.printStackTrace();
            }
        }
    }

//信息分发
    public void sendToOther(String msg, SocketChannel selfSocketChannel) throws Exception {
        //获得所有的信道，可以理解为获取所有的用户
        Set<SelectionKey> set = selector.keys();
        for (SelectionKey key : set) {
            Channel channel = key.channel();
            //判断这是一个用户，并且不是发信息的那个人
            //这个是一个 socketchannel 并且不等价与我们发信息的 selfsocketchannel
            if (channel instanceof SocketChannel && channel != selfSocketChannel) {
                SocketChannel socketChannel = (SocketChannel) channel;
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                socketChannel.write(buffer);
            }
        }
    }
//启动客户端，等待连接
    public static void main(String[] args) throws Exception {
        chatServer chatServer = new chatServer();
        chatServer.listenClient();
    }

客户端

---------------------初始化------------------------------
1.连接服务端通道
2.开启选择器
3.注册任务，打印上线日志
--------------------发送信息-------------------
1.向服务端发送信息
--------------------读取信息---------------------
1.接收服务端分发的消息（自己除外）

//服务端通道
    private SocketChannel channel;
    // 多路复用选择器
    private Selector selector;

    public chatClient() throws Exception {
        channel = SocketChannel.open();
        selector = Selector.open();
        SocketAddress address = new InetSocketAddress("127.0.0.1", 6666);
        channel.connect(address);
        channel.configureBlocking(false);
        channel.register(selector, SelectionKey.OP_READ);
        System.out.println("用户：" + channel.getLocalAddress() + "上线了");
    }

    public void sendData(String msg) {
        try {
            ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
            channel.write(buffer);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void readData() throws Exception {
        SocketChannel channel = null;
        while (true) {
            int num = selector.select();
            if (num == 0) {
                continue;
            }
            Set<SelectionKey> set = selector.selectedKeys();
            Iterator<SelectionKey> iterator = set.iterator();
            while (iterator.hasNext()) {
                SelectionKey key = iterator.next();
                iterator.remove();
                if (key.isReadable()) {
                    try {
                        //获取当前的信道
                        channel = (SocketChannel) key.channel();
                        //创建缓冲区
                        ByteBuffer buffer = ByteBuffer.allocate(1024);
                        int read = channel.read(buffer);
                        //>0代表有可读取的内容
                        if (read > 0) {
                            String msg = new String(buffer.array());
                            System.out.println(msg);
                        }
                    } catch (Exception e) {
                        e.printStackTrace();

                    }
                }
            }

        }
    }

    public static void main(String[] args) throws Exception {
        final chatClient client = new chatClient();
        new Thread() {
            @Override
            public void run() {
                while (true) {

                    try {
                        //一直阅读是否有信息
                        client.readData();
                        //每一秒阅读一次
                        sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        }.start();

        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextLine()) {
            String str = scanner.nextLine();
            client.sendData(str);
        }
    }

案例测试

只需要创建两个类，将客户端和服务端的代码放入IDE就可以启动代码了，小冷保证开箱即用哦~
客户端想要多开的话，打开这个选项就可以开很多个客户端程序了

效果图

服务端日志

客户端看到的信息