Java基于NIO實現(xiàn)群聊系統(tǒng)

更新時間：2021年11月23日 15:56:35 作者：Java硬件工程師

這篇文章主要為大家詳細介紹了Java基于NIO實現(xiàn)群聊系統(tǒng)，文中示例代碼介紹的非常詳細，具有一定的參考價值，感興趣的小伙伴們可以參考一下

本文實例為大家分享了Java基于NIO實現(xiàn)群聊系統(tǒng)的具體代碼，供大家參考，具體內(nèi)容如下

實例要求：

1.編寫一個 NIO 群聊系統(tǒng)，實現(xiàn)服務(wù)器端和客戶端之間的數(shù)據(jù)簡單通訊（非阻塞）

2.實現(xiàn)多人群聊

3.服務(wù)器端：可以監(jiān)測用戶上線，離線，并實現(xiàn)消息轉(zhuǎn)發(fā)功能

4.客戶端：通過 Channel 可以無阻塞發(fā)送消息給其它所有用戶，同時可以接受其它用戶發(fā)送的消息（有服務(wù)器轉(zhuǎn)發(fā)得到）

5.目的：進一步理解 NIO 非阻塞網(wǎng)絡(luò)編程機制

6.示意圖分析和代碼

// 服務(wù)端：

package com.atguigu.nio.groupchat;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.Channel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;

public class GroupChatServer {

    //定義屬性
    private Selector selector;
    private ServerSocketChannel listenChannel;

    private static final int PORT = 6667;

    //構(gòu)造器
    //初始化工作
    public GroupChatServer() {
        try {
            //得到選擇器
            selector = Selector.open();
            //ServerSocketChannel
            listenChannel = ServerSocketChannel.open();
            //綁定端口
            listenChannel.socket().bind(new InetSocketAddress(PORT));
            //設(shè)置非阻塞模式
            listenChannel.configureBlocking(false);
            //將該 listenChannel 注冊到 selector
            listenChannel.register(selector, SelectionKey.OP_ACCEPT);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void listen() {
        try {
            //循環(huán)處理
            while (true) {
                int count = selector.select();
                if (count > 0) { //有事件處理
                    // 遍歷得到 selectionKey 集合
                    Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                    while (iterator.hasNext()) {
                        //取出 selectionkey
                        SelectionKey key = iterator.next();
                        //監(jiān)聽到 accept
                        if (key.isAcceptable()) {
                            SocketChannel sc = listenChannel.accept();
                            sc.configureBlocking(false);
                            //將該 sc 注冊到 seletor
                            sc.register(selector, SelectionKey.OP_READ);
                            //提示
                            System.out.println(sc.getRemoteAddress() + " 上線 ");
                        }
                        if (key.isReadable()) {//通道發(fā)送read事件，即通道是可讀的狀態(tài)
                            // 處理讀(專門寫方法..)
                            readData(key);
                        }
                        //當(dāng)前的 key 刪除，防止重復(fù)處理
                        iterator.remove();
                    }
                } else {
                    System.out.println("等待....");
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //發(fā)生異常處理....
        }
    }

    //讀取客戶端消息
    public void readData(SelectionKey key) {
        SocketChannel channel = null;
        try {
            //得到 channel
            channel = (SocketChannel) key.channel();
            //創(chuàng)建 buffer
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            int count = channel.read(buffer);
            //根據(jù) count 的值做處理
            if (count > 0) {
                //把緩存區(qū)的數(shù)據(jù)轉(zhuǎn)成字符串
                String msg = new String(buffer.array());
                //輸出該消息
                System.out.println("form客戶端:" + msg);
                //向其它的客戶端轉(zhuǎn)發(fā)消息(去掉自己),專門寫一個方法來處理
                sendInfoToOtherClients(msg, channel);
            }
        } catch (IOException e) {
            try {
                System.out.println(channel.getRemoteAddress() + "離線了..");
                //取消注冊
                key.cancel();
                //關(guān)閉通道
                channel.close();
            } catch (IOException e2) {
                e2.printStackTrace();
            }
        }
    }

    //轉(zhuǎn)發(fā)消息給其它客戶(通道)
    private void sendInfoToOtherClients(String msg, SocketChannel self) throws IOException {

        System.out.println("服務(wù)器轉(zhuǎn)發(fā)消息中...");
        //遍歷所有注冊到 selector 上的 SocketChannel,并排除 self
        for (SelectionKey key : selector.keys()) {
            //通過 key 取出對應(yīng)的 SocketChannel
            Channel targetChannel = key.channel();
            //排除自己
            if (targetChannel instanceof SocketChannel && targetChannel != self) {
                //轉(zhuǎn)型
                SocketChannel dest = (SocketChannel) targetChannel;
                //將 msg 存儲到 buffer
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                //將 buffer 的數(shù)據(jù)寫入通道
                dest.write(buffer);
            }
        }
    }

    public static void main(String[] args) {
        //創(chuàng)建服務(wù)器對象
        GroupChatServer groupChatServer = new GroupChatServer();
        groupChatServer.listen();
    }
}

// 客戶端：

package com.atguigu.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 {
    //定義相關(guān)的屬性
    private final String HOST = "127.0.0.1";//服務(wù)器的ip
    private final int PORT = 6667;//服務(wù)器端口
    private Selector selector;
    private SocketChannel socketChannel;
    private String username;
    //構(gòu)造器,完成初始化工作
    public GroupChatClient() throws IOException {
        
        selector = Selector.open();
        //連接服務(wù)器
        socketChannel = SocketChannel.open(new InetSocketAddress(HOST, PORT));
        //設(shè)置非阻塞
        socketChannel.configureBlocking(false);
        //將 channel 注冊到selector
        socketChannel.register(selector, SelectionKey.OP_READ);
        //得到 username
        username = socketChannel.getLocalAddress().toString().substring(1);
        System.out.println(username + " is ok...");
    }
    //向服務(wù)器發(fā)送消息
    public void sendInfo(String info) {
        info = username + " 說：" + info;
        try {
            socketChannel.write(ByteBuffer.wrap(info.getBytes()));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    //讀取從服務(wù)器端回復(fù)的消息
    public void readInfo() {
        try {
            int readChannels = selector.select();
            if (readChannels > 0) {//有可以用的通道
                Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                while (iterator.hasNext()) {
                    SelectionKey key = iterator.next();
                    if (key.isReadable()) {
                        //得到相關(guān)的通道
                        SocketChannel sc = (SocketChannel) key.channel();
                        //得到一個 Buffer
                        ByteBuffer buffer = ByteBuffer.allocate(1024);
                        //讀取
                        sc.read(buffer);
                        //把讀到的緩沖區(qū)的數(shù)據(jù)轉(zhuǎn)成字符串
                        String msg = new String(buffer.array());
                        System.out.println(msg.trim());
                    }
                }
                iterator.remove(); //刪除當(dāng)前的 selectionKey,防止重復(fù)操作
            } else {
                //System.out.println("沒有可以用的通道...");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) throws Exception {
        //啟動我們客戶端
        GroupChatClient chatClient = new GroupChatClient();
        //啟動一個線程,每個 3 秒，讀取從服務(wù)器發(fā)送數(shù)據(jù)
        new Thread() {
            public void run() {
                while (true) {
                    chatClient.readInfo();
                    try {
                        Thread.currentThread().sleep(3000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }.start();
        //發(fā)送數(shù)據(jù)給服務(wù)器端
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextLine()) {
            String s = scanner.nextLine();
            chatClient.sendInfo(s);
        }
    }
}

運行結(jié)果