netty ？-32 用NIO来实现简单的群聊系统

Client 代码如下

package chat;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
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 GCli {
    private static final int PORT = 6767;
    private static final String HOST = "127.0.0.1";
    private Selector selector;
    private SocketChannel socketChannel;
    private String name;

    public static void main(String[] args) {
        GCli gCli = new GCli();
        new Thread(){
            @Override
            public void run() {
                while (true) {

                gCli.read();
                try {
                    Thread.currentThread().sleep(3000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                }

            }
        }.start();


        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextLine()) {
            String str = scanner.nextLine();
            gCli.send(str);
        }
    }


    public GCli() {
        try {
            selector = Selector.open();
            socketChannel = SocketChannel.open(new InetSocketAddress(HOST, PORT));
            socketChannel.configureBlocking(false);
            socketChannel.register(selector, SelectionKey.OP_READ);
            name = socketChannel.getLocalAddress().toString().substring(1);
            SocketAddress localAddress = socketChannel.getLocalAddress();
            System.out.println(localAddress.toString());

            System.out.println("客户端："+name+" is ok");

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

    public void send(String msg) {
        msg = name+"说：" + msg;
        try {
            socketChannel.write(ByteBuffer.wrap(msg.getBytes()));

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

    public void read() {
        try {
            int count = selector.select();
            if (count > 0) {
                Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
                while (iterator.hasNext()) {
                    SelectionKey key = iterator.next();
                    if (key.isReadable()) {
                        SocketChannel soc = (SocketChannel) key.channel();
                        ByteBuffer buf = ByteBuffer.allocate(1024);

                        int num = soc.read(buf);
                        System.out.println(new String(buf.array()));
                    }
                }
                iterator.remove();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Server 代码如下

package chat;

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

public class GSer {
    private static final int PORT = 6767;
    private Selector selector;
    private ServerSocketChannel serverSocketChannel;
//    private

    public static void main(String[] args) {
        GSer gSer = new GSer();
        gSer.listen();
    }

    public GSer() {
        try {
            selector = Selector.open();
            serverSocketChannel = ServerSocketChannel.open();
            serverSocketChannel.configureBlocking(false);
//            serverSocketChannel.bind(new InetSocketAddress(PORT));
            serverSocketChannel.socket().bind(new InetSocketAddress(PORT));
            serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

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

    public void listen(){
        while (true) {
            try {
                int count = selector.select();
                if (count > 0) {
                    Set<SelectionKey> selectionKeys = selector.selectedKeys();
                    Iterator<SelectionKey> keys = selectionKeys.iterator();
                    while (keys.hasNext()) {
                        SelectionKey key = keys.next();
                        if (key.isAcceptable()) {
                            ServerSocketChannel serverSocketChannel = (ServerSocketChannel) key.channel();
                            SocketChannel serverSocket = serverSocketChannel.accept();
                            serverSocket.configureBlocking(false);
                            serverSocket.register(selector, SelectionKey.OP_READ, ByteBuffer.allocate(1234));
                            System.out.println("serverSocket = " + serverSocket.getRemoteAddress()+"上线了");

                        }
                        if (key.isReadable()) {
                            read(key);
                        }

                        keys.remove();
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
            }
        }
    }

    private void read(SelectionKey key) {
        SocketChannel socketChannel = (SocketChannel) key.channel();
//         ByteBuffer buffer= (ByteBuffer) key.attachment();
        try {
            ByteBuffer buffer=ByteBuffer.allocate(1213);
            int count = socketChannel.read(buffer);
            if (count > 0) {
                String msg = new String(buffer.array());
                System.out.println("read方法 = " + msg);
                sendTo(msg, socketChannel);
            }
        } catch (IOException e) {
            try {
                System.out.println("socketChannel.getRemoteAddress() = " + socketChannel.getRemoteAddress()+"客户端离开了");
                key.cancel();
                socketChannel.close();
            } catch (IOException e1) {
                e1.printStackTrace();
            }
            e.printStackTrace();
        }
    }

    private void sendTo(String msg, SocketChannel socketChannel) {
        System.out.println("服务器开始转发了==========");
        //也就是把所有注册到selector上的channel都转发一份，但是没有自身
        for (SelectionKey selectionKey : selector.keys()) {
            SelectableChannel soc = selectionKey.channel();
            if (soc instanceof  SocketChannel &&soc != socketChannel) {
                try {

                    ((SocketChannel)soc).write(ByteBuffer.wrap(msg.getBytes()));
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
        }
    }
}

以上代码中需要注意的问题，主要有SocketChannel 的configBlocking（false）
还有就是iterater中的问题。 要remove（）既然remove 必须和next 方法配合使用。那么怎么用呢？

就是