Java基于NIO实现群聊功能

package com.dashu.netty.group_chat;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.nio.charset.StandardCharsets;
import java.util.Iterator;
public class GroupChatServer {
    /**
     * 初始化选择器
     */
    private Selector selector;
    /**
     * 初始化服务器网络通道
     */
    private ServerSocketChannel serverSocketChannel;
    /**
     * 端口
     */
    private static final int PORT = 6666;
    /**
     * 构造方法
     */
    public GroupChatServer() {
        try {
            //获取选择器
            selector = Selector.open();
            //获取服务器网络通道
            serverSocketChannel = ServerSocketChannel.open();
            //网络地址
            InetSocketAddress inetSocketAddress = new InetSocketAddress(PORT);
            //服务器网络通道绑定网络地址
            serverSocketChannel.socket().bind(inetSocketAddress);
            //设置服务器网络通道非阻塞
            serverSocketChannel.configureBlocking(false);
            //将服务器网络通道注册到选择器上，绑定连接请求事件
            serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * 监听客户端请求事件
     */
    public void listen() {
        try {
            //无限循环
            while (true) {
                //获取请求数
                int count = selector.select();
                //count大于0，则代表有请求进来
                if (count > 0) {
                    //获取请求集
                    Iterator<SelectionKey> selectionKeyIterator = selector.selectedKeys().iterator();
                    //遍历请求集
                    while (selectionKeyIterator.hasNext()) {
                        //得到请求
                        SelectionKey selectionKey = selectionKeyIterator.next();
                        //连接请求
                        if (selectionKey.isAcceptable()) {
                            //获取客户端网络通道
                            SocketChannel socketChannel = serverSocketChannel.accept();
                            //设置客户端网络通道非阻塞
                            socketChannel.configureBlocking(false);
                            //将客户端网络通道注册到选择器上
                            socketChannel.register(selector, SelectionKey.OP_READ);
                            System.out.println(socketChannel.getRemoteAddress() + "上线了");
                        }
                        //信息读取请求
                        if (selectionKey.isReadable()) {
                            //客户端信息读取
                            readData(selectionKey);
                        }
                        //移除请求
                        selectionKeyIterator.remove();
                    }
                } else {
                    System.out.println("等待...");
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * 客户端信息读取
     *
     * @param selectionKey
     */
    private void readData(SelectionKey selectionKey) {
        //初始化客户端网络通道
        SocketChannel socketChannel = null;
        try {
            //获取客户端网络通道
            socketChannel = (SocketChannel) selectionKey.channel();
            //创建缓冲区
            ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
            //读取客户端网络通道中的数据到缓冲区
            int count = socketChannel.read(byteBuffer);
            //判断缓冲区中是否有数据
            if (count > 0) {
                //将缓冲区的数据转换位字符串
                String message = new String(byteBuffer.array());
                System.out.println(message.trim());
                //将信息群发到其他客户端
                sendInfoToOtClients(message, socketChannel);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * 将信息群发到其他客户端
     *
     * @param message
     * @param socketChannel
     */
    private void sendInfoToOtClients(String message, SocketChannel socketChannel) {
        //获取所有注册到选择器的客户端，并遍历
        for (SelectionKey selectionKey : selector.keys()) {
            //获取通道
            Channel channel = selectionKey.channel();
            //判断通道是否属于SocketChannel，同时不等于发送信息的客户端
            if (channel instanceof SocketChannel && channel != socketChannel) {
                //通道转换
                SocketChannel sc = (SocketChannel) channel;
                //将信息写入缓冲区
                ByteBuffer byteBuffer = ByteBuffer.wrap(message.getBytes(StandardCharsets.UTF_8));
                try {
                    //将缓冲区的数据写入通道
                    sc.write(byteBuffer);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
    public static void main(String[] args) {
        GroupChatServer groupChatServer = new GroupChatServer();
        System.out.println("服务器启动，开始监听客户端请求...");
        groupChatServer.listen();
    }
}

package com.dashu.netty.group_chat;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.nio.charset.StandardCharsets;
import java.util.Iterator;
import java.util.Scanner;
public class GroupChatClient {
    /**
     * 网络连接地址
     */
    private final String HOST = "127.0.0.1";
    /**
     * 端口
     */
    private final int PORT = 6666;
    /**
     * 初始化选择器
     */
    private Selector selector;
    /**
     * 初始化网络通道
     */
    private SocketChannel socketChannel;
    /**
     * 用户名
     */
    private String username;
    public GroupChatClient() {
        try {
            //获取选择器
            selector = Selector.open();
            //获取服务器网络地址
            InetSocketAddress inetSocketAddress = new InetSocketAddress(HOST, PORT);
            //获取网络通道
            socketChannel = SocketChannel.open(inetSocketAddress);
            //设置网络通道非阻塞
            socketChannel.configureBlocking(false);
            //将网络通道注册到选择器
            socketChannel.register(selector, SelectionKey.OP_READ);
            //获取用户名
            System.out.println("请输入用户名：");
            Scanner scanner = new Scanner(System.in);
            username = scanner.nextLine();
            System.out.println(username + " 进入群聊...");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * 向服务器发送信息
     *
     * @param message
     */
    public void sendInfo(String message) {
        message = username + ":" + message;
        try {
            //向通道写入数据
            socketChannel.write(ByteBuffer.wrap(message.getBytes(StandardCharsets.UTF_8)));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * 读取服务器发来的信息
     */
    public void readInfo() {
        try {
            //获取请求数
            int count = selector.select();
            if (count > 0) {
                //获取请求集
                Iterator<SelectionKey> selectionKeyIterator = selector.selectedKeys().iterator();
                //遍历请求集
                while (selectionKeyIterator.hasNext()) {
                    //获取请求
                    SelectionKey selectionKey = selectionKeyIterator.next();
                    //判断位读请求
                    if (selectionKey.isReadable()) {
                        //获取通道
                        SocketChannel sc = (SocketChannel) selectionKey.channel();
                        //创建缓冲区
                        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
                        //读取通道的数据到缓冲区
                        sc.read(byteBuffer);
                        //缓冲区数据转字符串
                        String message = new String(byteBuffer.array());
                        //输出
                        System.out.println(message.trim());
                    }
                    //移除已完成请求
                    selectionKeyIterator.remove();
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) {
        GroupChatClient groupChatClient = new GroupChatClient();
        /**
         * 开启一个线程，每3秒读取一次服务器发来的信息
         */
        new Thread() {
            @Override
            public void run() {
                while (true) {
                    groupChatClient.readInfo();
                    try {
                        Thread.sleep(3000);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        }.start();
        //信息输入
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入信息：");
        while (scanner.hasNextLine()) {
            String s = scanner.nextLine();
            //信息发送
            groupChatClient.sendInfo(s);
            System.out.println("请输入信息：");
        }
    }
}