【nio网络编程】发送消息

写的比较简单，没有异步输入消息，参考韩顺平老师的讲解

server.java

package com.company;

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

public class Server {
    static Selector selector ;
    static ServerSocketChannel serverSocketChannel;

    public static void main(String[] args) throws Exception {
        selector = Selector.open();
        serverSocketChannel = ServerSocketChannel.open();
        serverSocketChannel.bind(new InetSocketAddress(8080));

        serverSocketChannel.configureBlocking(false);
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

        while (true) {
            int count = selector.select(1000);
            if (count > 0) {
                Set<SelectionKey> selectionKeys = selector.selectedKeys();
                Iterator<SelectionKey> iterator = selectionKeys.iterator();

                while (iterator.hasNext()) {
                    SelectionKey key = iterator.next();
                    if (key.isAcceptable()) {
                        SocketChannel accept = serverSocketChannel.accept();
                        accept.configureBlocking(false);
                        accept.register(selector, SelectionKey.OP_READ);
                        System.out.println(accept.getRemoteAddress() + " 上线了");
                    }
                    if (key.isReadable()) {
                        // todo
                        readData(key);
                    }
                    iterator.remove();
                }


            } else {
//                System.out.println("等待ing");
            }

        }


    }

    private static void readData(SelectionKey key) {
        SocketChannel channel = null;
        try {
            channel = (SocketChannel)key.channel();
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            int read = channel.read(buffer);
            if (read>0) {
                String string = new String(buffer.array(), 0, buffer.position(), StandardCharsets.UTF_8);
                System.out.println("客户端发送"+string);
                sendInfoToOther(string, channel);
            }
        } catch (IOException e) {
            try {
                System.out.println(channel.getRemoteAddress() + "离线了");
                key.cancel();
                channel.close();
                e.printStackTrace();
            } catch (IOException ex) {
                ex.printStackTrace();
            }

        }


    }

    private static void sendInfoToOther(String string, SocketChannel self) throws IOException {
        for (SelectionKey key : selector.keys()) {
            Channel channel = key.channel();
            if(channel instanceof SocketChannel && channel != self ){
                SocketChannel target = (SocketChannel) channel;
                ByteBuffer buffer = ByteBuffer.wrap(string.getBytes(StandardCharsets.UTF_8));
                target.write(buffer);
            }

        }
    }
}

Client.java

package com.company;

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.nio.charset.StandardCharsets;
import java.util.Iterator;
import java.util.Set;

public class Client {
    public static void main(String[] args) throws IOException {
        Selector selector = Selector.open();
        SocketChannel sc = SocketChannel.open(new InetSocketAddress("127.0.0.1", 8080));
        sc.configureBlocking(false);
        sc.register(selector, SelectionKey.OP_READ);

        String username = sc.getLocalAddress().toString().substring(1);
        System.out.println("username" + username);
        sc.write(ByteBuffer.wrap((username + "说 你好").getBytes(StandardCharsets.UTF_8)));

        while (true) {
            int count = selector.select(1000);
            if (count > 0) {
                Set<SelectionKey> selectionKeys = selector.selectedKeys();
                Iterator<SelectionKey> iterator = selectionKeys.iterator();
                while (iterator.hasNext()) {
                    SelectionKey next = iterator.next();
                    if (next.isReadable()) {
                        SocketChannel channel = (SocketChannel) next.channel();
                        ByteBuffer buff = ByteBuffer.allocate(1024);
                        channel.read(buff);
                        String s = new String(buff.array(), 0, buff.position(), StandardCharsets.UTF_8);
                        System.out.println(s);
                    } else {
                        System.out.println("没有可用的通道");
                    }
                    iterator.remove();
                }
            }
        }


    }


}