NIO多端口监听

1、NIOServerTest.java

package com.neohope.multisocket;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.Set;

public class NIOServerTest {
    public static void StartSockets() throws IOException {
        Selector selector = Selector.open();

        int[] ports = {4000, 4001, 4002};
        for (int port : ports) {
            ServerSocketChannel server = ServerSocketChannel.open();
            server.configureBlocking(false);
            server.socket().bind(new InetSocketAddress(port));
            //只处理了建立连接的消息
            server.register(selector, SelectionKey.OP_ACCEPT);
        }

        int serverPort = 0;
        ByteBuffer byteBuffer = null;
        ServerSocketChannel serverChannel = null;
        SocketChannel clientChannel = null;
        while (selector.isOpen()) {
            selector.select();
            Set<SelectionKey> readyKeys = selector.selectedKeys();
            Iterator<SelectionKey> keyIterator = readyKeys.iterator();
            while (keyIterator.hasNext()) {
                SelectionKey selectedKey = keyIterator.next();
                keyIterator.remove();
                if (selectedKey.isAcceptable()) {
                    serverChannel = (ServerSocketChannel) selectedKey.channel();
                    serverPort = serverChannel.socket().getLocalPort();
                    clientChannel = serverChannel.accept();
                    clientChannel.configureBlocking(false);
                    switch (serverPort) {
                        case 4000:
                            byteBuffer=ByteBuffer.wrap("welcome to port 4000".getBytes(Charset.forName("UTF-8")));
                            clientChannel.write(byteBuffer);
                            break;
                        case 4001:
                            byteBuffer=ByteBuffer.wrap("welcome to port 4001".getBytes(Charset.forName("UTF-8")));
                            clientChannel.write(byteBuffer);
                            break;
                        case 4002:
                            byteBuffer=ByteBuffer.wrap("welcome to port 4002".getBytes(Charset.forName("UTF-8")));
                            clientChannel.write(byteBuffer);
                            break;
                    }
                }
            }
        }
    }

    public static void main(String[] args) throws IOException {
        StartSockets();
    }
}

2、NIOClientTest.java

package com.neohope.multisocket;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;

public class NIOClientTest {
    public static void StartClient(String host, int port)
    {
        int readSize = 0;
        SocketChannel clientChannel = null;
        SocketAddress socketAddress = new InetSocketAddress(host, port);
        byte[] bytes;
        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        try {
            clientChannel = SocketChannel.open();
            clientChannel.connect(socketAddress);
            try {
                while ((readSize = clientChannel.read(byteBuffer)) >= 0) {
                    byteBuffer.flip();
                    bytes = new byte[readSize];
                    byteBuffer.get(bytes);
                    byteArrayOutputStream.write(bytes);
                    byteBuffer.clear();
                    //服务端没有主动关闭连接，读取少于1024，假设读取完毕
                    if(readSize<1024)break;
                }
                System.out.println(byteArrayOutputStream.toString());
            } catch (IOException ex) {
                ex.printStackTrace();
            } finally {
                try {
                    byteArrayOutputStream.close();
                } catch(Exception ex) {}
            }
        } catch (IOException ex) {
            ex.printStackTrace();
        } finally {
            try {
                clientChannel.close();
            } catch(Exception ex) {}
        }
    }

    public static void main(String[] args) throws IOException {
        StartClient("localhost",4000);
        StartClient("localhost",4001);
        StartClient("localhost",4002);
    }
}