NIO简单群聊

server

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;

public class GroupServer {

    private Selector selector;

    private ServerSocketChannel serverSocketChannel;

    private static final int PORT = 6667;

    public GroupServer() {
        try {
            selector = Selector.open();
            serverSocketChannel = ServerSocketChannel.open();
            serverSocketChannel.configureBlocking(false);
            serverSocketChannel.socket().bind(new InetSocketAddress(PORT));
            serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 监听
     */
    public void listen() {
        System.out.println("开始监听");
        try {
            // 需要轮询获取事件
            while (true) {
                // 阻塞两秒 获取事件
                int count = selector.select(2000);
                if (count > 0) {
                    // 有事件进来了  有可能并发来的 所以需要循环 获取事件 并处理
                    Iterator<SelectionKey> keyIterator = selector.selectedKeys().iterator();
                    while (keyIterator.hasNext()) {
                        SelectionKey key = keyIterator.next();
                        // 这块是先关心accept事件  获取之后 立马就关心read事件
                        if (key.isAcceptable()) {
                            // 获取到客户端的连接
                            SocketChannel sc = serverSocketChannel.accept();
                            // 设置非阻塞 注册到selector 关注read事件 并给一个buffer
                            sc.configureBlocking(false);
                            sc.register(selector, SelectionKey.OP_READ);
                            System.out.println("用户 " + sc.getRemoteAddress() + " 上线了");
                        }
                        // 立马关注读事件
                        if (key.isReadable()) {
                            // selectionKey 和channel是绑定的 1对1  key中也就是事件 绑定channel 获取数据
                            readData(key);
                        }
                    }

                    keyIterator.remove();
                }else {
//                    System.out.println("等待中。。。");
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {

        }
    }

    /**
     * 发送消息给其他客户端
     * @param msg
     * @param self
     */
    public void sendInfoToOtherClients(String msg, SocketChannel self) {
        try {
            // 遍历所有注册到selector上的socketChannel 并排除自己
            for (SelectionKey key : selector.keys()) {
                Channel channel = key.channel();
                if (channel instanceof SocketChannel && channel != self) {
                    ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                    ((SocketChannel) channel).write(buffer);
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {

        }

    }

    /**
     * 读取客户端消息
     * @param key
     */
    private void readData(SelectionKey key) {
        SocketChannel socketChannel = null;
        try {
            socketChannel = (SocketChannel) key.channel();
            // 创建buffer 读取数据
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            int count = socketChannel.read(buffer);
            //根据count的值做处理
            if (count > 0) {
                //读取到数据
                String msg = new String(buffer.array());
                System.out.println("from client 消息：" + msg.trim());
                //向其他客户端转发消息
                sendInfoToOtherClients(msg, socketChannel);
            }
        } catch (Exception e) {
            try {
                System.out.println(socketChannel.getRemoteAddress() + " 离线了");
                key.cancel();
                socketChannel.close();
            } catch (IOException e2) {
                e2.printStackTrace();
            }
        } finally {

        }
    }

    public static void main(String[] args) {
        try {
            GroupServer groupServer = new GroupServer();
            groupServer.listen();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {

        }
    }
}

client

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;

public class GroupClient {

    private static final String HOST = "127.0.0.1";
    private static final int PORT = 6667;
    private Selector selector;

    private String userName;

    private SocketChannel socketChannel;

    public GroupClient() throws Exception {
        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 + " client 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(2000);
            if (readChannels > 0) {
                Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                while (iterator.hasNext()){
                    SelectionKey key = iterator.next();
                    if (key.isReadable()) {
                        SocketChannel sc = (SocketChannel) key.channel();
                        ByteBuffer buffer = ByteBuffer.allocate(1024);
                        sc.read(buffer);
                        String msg = new String(buffer.array());
                        System.out.println(msg.trim());
                    }
                    iterator.remove();
                }
            }else {
//                System.out.println("没有可用的通道");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {

        }
    }

    public static void main(String[] args) throws Exception {
        GroupClient client = new GroupClient();
        // 开启一个线程 读取从服务器端回复的消息 （客户端）
        new Thread(()->{
            while (true) {
                 client.readInfo();
                 try {
                     Thread.sleep(3000);
                 } catch (Exception e) {
                     e.printStackTrace();
                 }
             }
        }).start();
        // 主线程 发送数据给服务器端
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextLine()) {
            String s = scanner.nextLine();
            client.sendInfo(s);
        }
    }

}