NIO 网络编程应用实例-群聊系统（六）

NIO 网络编程应用实例-群聊系统

实例要求:

1. 编写一个 NIO 群聊系统，实现服务器端和客户端之间的数据简单通讯（非阻塞）
2. 实现多人群聊
3. 服务器端：可以监测用户上线，离线，并实现消息转发功能
4. 客户端：通过 channel 可以无阻塞发送消息给其它所有用户，同时可以接受其它用户发送的消息(有服务器转发
   得到)
5. 目的：进一步理解 NIO 非阻塞网络编程机制

1.服务端

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 PORT = 6667;

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

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

    //监听
    public void listen(){
        try{
            while (true){
                int count = selector.select(2000);
                if(count>0){
                    //遍历得到的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);
                            //将该sc注册到 seletor
                            sc.register(selector,SelectionKey.OP_READ);
                            //给出提示
                            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
                            //处理器（专门写方法。。）
                            readData(key);
                        }
                        //当前的key删除，防止重复处理
                        //手动从集合中移动当前的selectionKey，防止重复操作
                        iterator.remove();
                    }
                }else {
                    System.out.println("等待。。。");
                }
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {

        }
    }

    //读取客户端消息
    private void readData(SelectionKey key)  {
        //定义一个SocketChannel
        SocketChannel channel = null;
        try{
            channel = (SocketChannel) key.channel();
            //创建buffer
            ByteBuffer buffer = ByteBuffer.allocate(1024);

            int count = channel.read(buffer);
            //根据count的值做处理
            if(count>0){
                //把缓存区的数据转换成字符串
                String msg = new String(buffer.array());
                //输出该消息
                System.out.println("from 客户端："+msg);

                //向其他的客户端转发消息(去掉自己)，专门写一个方法来处理
                sendInfoToOtherClients(msg,channel);
            }
        }catch (Exception e){
            try {
                System.out.println(channel.getRemoteAddress()+" 离线了..");
                //取消注册
                key.cancel();
                //关闭通道
                channel.close();
            } catch (IOException e1) {
                e1.printStackTrace();
            }
        }
    }

    //转发消息给其他客户（通道）
    private void sendInfoToOtherClients(String msg,SocketChannel self) throws IOException {
        System.out.println("服务器转发消息中...");
        //遍历 所有注册到selector 上的 SocketChannel，并排除self
        for(SelectionKey key: selector.keys()){
            //遍历 key 取出对应的SocketChannel
            Channel targetChannel = key.channel();

            //排除自己
            if(targetChannel instanceof SocketChannel&&targetChannel!=self){
                //转型
                SocketChannel dest = (SocketChannel)targetChannel;
                //将msg 存储到buffer
                ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
                //将buffer 的数据写入通道
                dest.write(buffer);
            }

        }

    }

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

2.客户端

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 {
    private final String Host ="127.0.0.1";
    private final int PORT = 6667;
    private Selector selector;
    private SocketChannel socketChannel;
    private String username;

    //构造器，完成初始化工作
    public GroupChatClient() throws IOException {
        selector = Selector.open();
        //连接服务器
        socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", PORT));
        //设置非阻塞
        socketChannel.configureBlocking(false);
        //将channel 注册到selector
        socketChannel.register(selector, SelectionKey.OP_READ);
        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 (Exception e){
            e.printStackTrace();
        }
    }

    //读取从服务器端回复的消息
    public void rendInfo(){
        try{
            int readChannels = selector.select();
            if(readChannels>0){ //即有可用的通道
                Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                while(iterator.hasNext()){
                    SelectionKey key = iterator.next();
                    if(key.isReadable()){
                        //得到相关的通道
                        SocketChannel sc = (SocketChannel)key.channel();
                        //得到一个Buffer
                        ByteBuffer buffer = ByteBuffer.allocate(1024);
                        //读取
                        sc.read(buffer);
                        //把读到的缓存区的数据转换成字符串
                        String msg = new String(buffer.array());
                        System.out.println(msg.trim());

                    }
                }
                iterator.remove(); //删除当前的selectionkey，防止重复操作
            }else {
//                System.out.println("没有可用的通道...");

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

    public static void main(String[] args) throws IOException {
        //启动我们客户端
        GroupChatClient chatClient = new GroupChatClient();

        //启动一个线程
        new Thread() {
            @Override
            public void run() {
                while (true) {
                    chatClient.rendInfo();
                    try {
                        sleep(3000);
                    }catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }.start();

        //发送数据给客户端
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextLine()){
            String s = scanner.nextLine();
            chatClient.sendInfo(s);
        }

    }

}

3.部分截图