NIO实现简单群聊系统

服务端

package com.jhj.nio.groupchat;

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

public class GroupChatServer {
    
    //定义属性
    private Selector selector;
    private ServerSocketChannel listenChannel;
    private static final int PROT = 6667;

    //构造器
    public GroupChatServer() {
    
        //初始化
        try {
    
            //得到选择器
            selector = Selector.open();
            //ServerScoketChannel
            listenChannel=ServerSocketChannel.open();
            //绑定端口
            listenChannel.socket().bind(new InetSocketAddress(PROT));
            //设置非阻塞模式
            listenChannel.configureBlocking(false);
            //将该listenChannel注册到selector
            listenChannel.register(selector, SelectionKey.OP_ACCEPT);

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

    //监听
    public void listen() {
    
        try {
    
            //循环处理
            while (true) {
    
                int count = selector.select();
                //有事件处理
                if (count > 0) {
    
                    //遍历得到selectionKey集合
                    Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                    while (iterator.hasNext()) {
    
                        //取出selectionKey
                        SelectionKey key = iterator.next();
                        //监听到accept
                        if (key.isAcceptable()) {
    
                            SocketChannel sc = listenChannel.accept();
                            sc.configureBlocking(false);
                            sc.register(selector, SelectionKey.OP_READ);
                            System.out.println(sc.getRemoteAddress() + "上线");
                        }

                        if (key.isReadable()) {
    
                            //通道发送read事件，即通道是可读的状态
                            //处理读
                            readDate(key);
                        }
                        //删除 方式重复操作
                        iterator.remove();
                    }
                } else {
    
                    System.out.println("等待...");
                }
            }
        } catch (Exception e) {
    
            e.printStackTrace();
        } finally {
    

        }

    }

    //读取客户端消息
    private void readDate(SelectionKey key) {
    

        //定义一个SocketChannel

        SocketChannel channel = null;
        try {
    
            //得到channel
            channel = (SocketChannel) key.channel();

            //创建buffer
            ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
            //获取到该channel关联的buffer
            int count = channel.read(byteBuffer);
            //根据count的值做处理
            if (count > 0) {
    
                //把缓冲区的数据转成字符串
                String s = new String(byteBuffer.array());
                //输出
                System.out.println("from客户端：" + s);

                //向其他客户端转发消息
                sendInfoToOtherClients(s, channel);
            }

        } catch (IOException e) {
    

            try {
    
                System.out.println(channel.getRemoteAddress() + "离线了....");
                //取消注册
                key.cancel();
                //关闭通道
                channel.close();
            } catch (IOException ex) {
    
                ex.printStackTrace();
            }

        }
    }

    //转发消息给其他客户端（通道）
    private void sendInfoToOtherClients(String s, SocketChannel socketChannel) throws IOException {
    

        System.out.println("服务器转发消息中");
        //遍历所有注册到select上的SocketChannel 并排除自己
        for (SelectionKey key : selector.keys()) {
    
            //通过key获取 socketChannel
            Channel channel = key.channel();
            //排除自己
            if (channel instanceof SocketChannel && channel != socketChannel) {
    
                //转型
                SocketChannel channel1 = (SocketChannel) channel;
                //将s存储到buffer
                ByteBuffer wrap = ByteBuffer.wrap(s.getBytes());
                //将buffer数据写入通道
                channel1.write(wrap);
            }
        }


    }


    public static void main(String[] args) {
    
        //创建一个服务器对象
        GroupChatServer groupChatServer = new GroupChatServer();
        groupChatServer.listen();
    }
}

客户端

package com.jhj.nio.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;

public class GroupChatClient {
    

    //定义相关的属性
    private final String HOST="127.0.0.1";
    
    private final int PROT=6667;
    
    private Selector selector;
    private SocketChannel socketChannel;
    
    private String username;
    
    //构造器 完成初始化
    public GroupChatClient() throws IOException {
    
        selector = Selector.open();
        
        //连接服务器
        socketChannel=SocketChannel.open(new InetSocketAddress(HOST,PROT));
        //设置非阻塞
        socketChannel.configureBlocking(false);
        //将channel注册到Selector
        socketChannel.register(selector, SelectionKey.OP_READ);
        //得到username
        username = socketChannel.getLocalAddress().toString().substring(1);

        System.out.println(username+"is ok");
    }

    //向服务器发送消息
    public void sendInfo(String info){
    
        info=username+"说："+info;

        try {
    
            socketChannel.write(ByteBuffer.wrap(info.getBytes()));
        }catch (IOException e){
    
            e.printStackTrace();
        }
    }

    //读取从服务器端回复的消息
    public void readInfo(){
    
        try {
    
            int readChannels=selector.select(2000);
            if (readChannels>0){
    
                //有可用的通道

                Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                while (iterator.hasNext()){
    

                    SelectionKey next = iterator.next();
                    if (next.isReadable()){
    
                        //得到相关的通道
                        SocketChannel channel = (SocketChannel) next.channel();
                        //得到一个buffer
                        ByteBuffer allocate = ByteBuffer.allocate(1024);
                        //读取
                        channel.read(allocate);
                        //把读到的缓冲区的数据转成字符串
                        String s = new String(allocate.array());
                        System.out.println(s.trim());
                    }
                    //删除当前selectkey 防止重复操作
                    iterator.remove();
                }
            }else {
    
//                System.out.println("没有可以用的通道");
            }
        }catch (IOException e){
    
            e.printStackTrace();
        }
    }

    public static void main(String[] args) throws IOException {
    
        //启动客户端
        GroupChatClient groupChatClient = new GroupChatClient();
        //启动一个线程 每隔3秒 读取从服务器发送的数据
        new Thread(){
    
            public void run(){
    
                while (true){
    
                    groupChatClient.readInfo();
                    try{
    
                      Thread.currentThread().sleep(3000);
                    } catch (InterruptedException e){
    
                        e.printStackTrace();
                    }
                }
            }
        }.start();


        //发送数据
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextLine()){
    
            String s=scanner.nextLine();
            groupChatClient.sendInfo(s);
        }
    }
}

作者声明

如有问题，欢迎指正！