Netty由淺到深_第三章_NIO網絡編程實列-羣聊系統

要求

1）編寫一個NIO羣聊系統，實現服務器端和客戶端之間的數據簡單通訊
2）實現多人聊天
3）服務器端：可以檢測用戶上線，離線，並實現消息轉發功能
4）客戶端：通過channel可以無阻塞發送消息給其他所有用戶，同時可以接受其他用戶發送的消息

服務端

package com.dd.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 {
    //定義相關屬性
    private Selector selector;
    private ServerSocketChannel listenChannel;
    private static final int PORT = 6667;

    //構造器
    public GroupChatServer(){
        try {
            //得到選擇器
            selector = Selector.open();
            listenChannel = ServerSocketChannel.open();

            //綁定端口
            listenChannel.socket().bind(new InetSocketAddress(PORT));

            //設置非阻塞模式
            listenChannel.configureBlocking(false);

            //將該listenChannel註冊到selectorshang上
            listenChannel.register(selector, SelectionKey.OP_ACCEPT);

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

    //監聽代碼
    public void listen(){
        try {
            //循環處理
            while (true){
                int count = selector.select(2000);
                if (count>0){//有事件處理

                    //遍歷得到的selectionKey集合
                    Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                    while (iterator.hasNext()){
                        //取出selectionKey
                        SelectionKey key = iterator.next();

                        //監聽到連接事件
                        if (key.isAcceptable()){
                            SocketChannel socketChannel = listenChannel.accept();
                            socketChannel.configureBlocking(false);
                            //將該socketChannel註冊到selector上
                            socketChannel.register(selector,SelectionKey.OP_READ);
                            //提示某某上線
                            System.out.println(socketChannel.getRemoteAddress()+"上線");

                        }
                        //讀取數據事件
                        if(key.isReadable()){//通道是可讀狀態
                            readData(key);
                        }

                        //當前的key刪除，防止重複處理
                        iterator.remove();

                    }

                }else {
                    System.out.println("等待連接");
                }
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {

        }
    }

    //讀取客戶端消息
    private void readData(SelectionKey key){
        //定義一個socketChannel
        SocketChannel channel = null;
        try {
           channel =  (SocketChannel)key.channel();
           //創建buffer
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            int count = channel.read(buffer);

            //根部count的值做處理
            if (count>0){
                String msg = new String(buffer.array());
                //輸出消息
                System.out.println("from客戶端"+msg);

                //向其他的客戶端轉發消息
                sendInfoToOtherClients(msg,channel);

            }

        }catch (IOException e){
            try {
                System.out.println(channel.getRemoteAddress()+"離線");

                //取消註冊，關閉通道
                key.cancel();
                channel.close();

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


    }

    //z轉發到其他客戶端
    private void sendInfoToOtherClients(String msg,SocketChannel self) throws IOException{
        //遍歷所有註冊到selector上的socketChannel,並排除自己
        for (SelectionKey key : selector.keys()){
            //通過key取出對應的socketChannel
            SelectableChannel targetChannel = key.channel();

            if (targetChannel instanceof SocketChannel && targetChannel != self){
               SocketChannel dest =  (SocketChannel)targetChannel;
               //將msg 存儲到buffer
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                //將buffer數據寫入到通道中
                dest.write(buffer);
            }

        }
    }

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

客戶端

package com.dd.nio.groupchat;

import javafx.beans.binding.When;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectableChannel;
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;

public class GroupChatClient {

    //定義相關屬性
    private final String HOST = "127.0.0.1";
    private final int PORT = 6667;
    private Selector selector;
    private SocketChannel socketChannel;
    private String userName;

    public GroupChatClient() throws IOException {
        //完成初始換工作
        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);
    }

    //向服務器發送消息
    public void sendInfo(String info){

        info = userName+"說："+info;

        try {
            socketChannel.write(ByteBuffer.wrap(info.getBytes()));

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

    //讀取服務器端的消息
    public void readInfo(){
        try {
            //沒寫參數 ，此時這裏阻塞
            int readChannels = selector.select();
            if (readChannels > 0){
                Set<SelectionKey> selectionKeys = selector.selectedKeys();
                Iterator<SelectionKey> iterator = selectionKeys.iterator();
                while (iterator.hasNext()){
                    SelectionKey next = iterator.next();
                    if (next.isReadable()){
                        //得到相關的通道
                        SocketChannel channel = (SocketChannel)next.channel();
                        ByteBuffer buffer = ByteBuffer.allocate(1024);
                        channel.read(buffer);
                        String msg = new String(buffer.array());
                        System.out.println(msg.trim());
                    }
                        iterator.remove();
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    public static void main(String[] args) throws Exception{

        //啓動客戶端
        GroupChatClient groupChatClient = new GroupChatClient();

        //啓動一個線程,每隔3秒從服務器端發送的數據
        new Thread(){
            @Override
            public void run() {
                while (true){
                    groupChatClient.readInfo();
                    try {
                        Thread.sleep(3000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }.start();

        //發送數據給服務器
        Scanner scanner = new Scanner(System.in);

        while (scanner.hasNextLine()){
            String s = scanner.nextLine();
            groupChatClient.sendInfo(s);
        }


    }

}

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