Netty实战与源码剖析（二）——基于NIO的群聊系统

package com.Zhongger.groupchat;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
import java.util.Set;
/**
 * @author zhongmingyi
 * @date 2021/9/25 3:07 下午
 */
public class GroupChatServer {
    private Selector selector;
    private ServerSocketChannel serverSocketChannel;
    private static final int PORT = 6666;
    public GroupChatServer() {
        try {
            selector = Selector.open();
            serverSocketChannel = ServerSocketChannel.open();
            serverSocketChannel.configureBlocking(false);
            serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
            serverSocketChannel.bind(new InetSocketAddress(PORT));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    //监听
    public void listen() {
        try {
            while (true) {
                int count = selector.select();
                if (count > 0) {
                    //有事件处理
                    Set<SelectionKey> selectionKeys = selector.selectedKeys();
                    Iterator<SelectionKey> iterator = selectionKeys.iterator();
                    while (iterator.hasNext()) {
                        SelectionKey selectionKey = iterator.next();
                        if (selectionKey.isAcceptable()) {
                            SocketChannel socketChannel = serverSocketChannel.accept();
                            socketChannel.configureBlocking(false);
                            socketChannel.register(selector, SelectionKey.OP_READ);
                            System.out.println(socketChannel.getRemoteAddress() + "上线了");
                        }
                        if (selectionKey.isReadable()) {
                            //处理读
                            readFromClient(selectionKey);
                        }
                        //手动将当前SelectionKey移除，防止重复处理
                        iterator.remove();
                    }
                } else {
                    System.out.println("等待事件......");
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
        }
    }
    private void readFromClient(SelectionKey selectionKey) {
        SocketChannel channel = null;
        try {
            channel = (SocketChannel) selectionKey.channel();
            ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
            int read = channel.read(byteBuffer);
            if (read > 0) {
                String msg = new String(byteBuffer.array());
                System.out.println("from 客户端：" + msg);
                //转发消息给其他客户端
                sendInfoToOtherClient(msg, channel);
            }
        } catch (Exception e) {
            try {
                System.out.println(channel.getRemoteAddress() + "离线了...");
                //取消注册
                selectionKey.cancel();
                //关闭通道
                channel.close();
            } catch (IOException ioException) {
                ioException.printStackTrace();
            }
        }
    }
    private void sendInfoToOtherClient(String msg, SocketChannel selfSocketChannel) throws IOException {
        System.out.println("服务器转发消息中...");
        //遍历所有注册到selector的key，并排查自己
        for (SelectionKey selectionKey : selector.keys()) {
            Channel targetChannel = selectionKey.channel();
            //排除自己
            if (targetChannel instanceof SocketChannel && targetChannel != selfSocketChannel) {
                SocketChannel destChannel = (SocketChannel) targetChannel;
                destChannel.write(ByteBuffer.wrap(msg.getBytes()));
            }
        }
    }
    public static void main(String[] args) {
        GroupChatServer server = new GroupChatServer();
        server.listen();
    }
}

package com.Zhongger.groupchat;
import java.io.IOException;
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.util.Iterator;
import java.util.Scanner;
import java.util.Set;
/**
 * @author zhongmingyi
 * @date 2021/9/25 3:44 下午
 */
public class GroupChatClient {
    private final String HOST = "127.0.0.1";
    private final Integer PORT = 6666;
    private Selector selector;
    private SocketChannel socketChannel;
    private String username;
    public GroupChatClient() throws IOException {
        selector = Selector.open();
        socketChannel = SocketChannel.open(new InetSocketAddress(HOST, PORT));
        socketChannel.configureBlocking(false);
        socketChannel.register(selector, SelectionKey.OP_READ);
        username = socketChannel.getLocalAddress().toString().substring(1);
        System.out.println(username + " is OK ...");
    }
    public void sendInfo(String info) {
        info = username + "说：" + info;
        try {
            socketChannel.write(ByteBuffer.wrap(info.getBytes()));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public void readInfo() {
        try {
            int readChannels = selector.select();
            if (readChannels > 0) {
                Set<SelectionKey> selectionKeys = selector.selectedKeys();
                Iterator<SelectionKey> iterator = selectionKeys.iterator();
                while (iterator.hasNext()) {
                    SelectionKey selectionKey = iterator.next();
                    if (selectionKey.isReadable()) {
                        SocketChannel channel = (SocketChannel) selectionKey.channel();
                        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
                        channel.read(byteBuffer);
                        String msg = new String(byteBuffer.array());
                        System.out.println(msg.trim());
                    }
                    iterator.remove();
                }
            } else {
                System.out.println("无可用的通道...");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) throws IOException {
        GroupChatClient client = new GroupChatClient();
        new Thread(() -> {
            while (true) {
                client.readInfo();
                try {
                    Thread.sleep(3000);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }).start();
        //发送数据
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextLine()) {
            String msg = scanner.nextLine();
            client.sendInfo(msg);
        }
    }
}