selector in client side(sorry forget the link from stackoverflow)

TcpTimeClient.java

package com.honey;

import java.io.File;
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.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.stream.IntStream;

public class TcpTimeClient {

    public static void main(String[] args) throws IOException {
        if (args.length < 2) {
            System.out.println("usage: <address> <port1> <port2>...");
            System.exit(1);
        }

        try (final Selector selector = Selector.open()) {
            tryAllConnections(selector, args[0],
                    Arrays.stream(args).skip(1).mapToInt(Integer::parseInt));
            if (selector.keys().size() == 0) {
                System.out.println("no connection can be attempted");
                System.exit(1);
            }

            boolean gotResp = false;
            while (!gotResp) {
                if (selector.select(3000) == 0) {
                    System.out.print("-");
                    continue;
                }
                final Iterator<SelectionKey> iter = selector.selectedKeys().iterator();
                while (iter.hasNext()) {
                    final SelectionKey key = iter.next();
                    if (key.isConnectable()) {
                        final SocketChannel sc = (SocketChannel) key.channel();
                        if (sc.finishConnect()) {
                            System.out.println("connected to: " + sc.getRemoteAddress());
                            key.interestOps(SelectionKey.OP_READ);
                        }

                    }
                    if (key.isReadable() && !gotResp) {
                        final SocketChannel sc = (SocketChannel) key.channel();
                        System.out.println("winner from: " + sc.getRemoteAddress());
                        final ByteBuffer bb = ByteBuffer.allocate(512);
                        final int bytesRead = sc.read(bb);
                        if (bytesRead == -1) {
                            System.out.println(" closed prematurely");
                            gotResp = true;
                            break;
                        }
                        System.out.println(" replied: " + new String(bb.array(), 0, bytesRead));
                        gotResp = true;
                        // just care about staff from first read
                        sc.close();
                    }
                    iter.remove();
                }
            }
            closeAll(selector);
        }
    }

    private static void closeAll(Selector selector) throws IOException {
        for (SelectionKey key : selector.keys()) {
            key.channel().close();
        }
    }

    private static void tryAllConnections(Selector selector, String address, IntStream ports) {
        ports.forEach(port -> {
            try {
                final SocketChannel sc = SocketChannel.open();
                sc.configureBlocking(false);
                sc.connect(new InetSocketAddress(address, port));
                sc.register(selector, SelectionKey.OP_CONNECT);
            } catch (IOException e) {
                System.out.println("connecting attempt to " + address + ":" + port + " failed");
            }
        });
    }

    public static Process start(String ...args) throws IOException {
        String javaHome = System.getProperty("java.home");
        String javaBin = javaHome + File.separator + "bin" + File.separator + "java";
        String classpath = System.getProperty("java.class.path");
        String className = TcpTimeClient.class.getCanonicalName();
        String[] cmd = {javaBin, "-cp", classpath, className};
        List<String> command = new ArrayList<>(Arrays.asList(cmd));
        command.addAll(Arrays.asList(args));
        ProcessBuilder builder = new ProcessBuilder(command.toArray(new String[0]));
        return builder.start();
    }
}

TestTcpTimeClient.java

package com.honey;

import org.junit.Test;

import java.io.*;

public class TestTcpTimeClient {

    @Test
    public void test() throws IOException, InterruptedException {
        String address = "bing.com";
        Process process = TcpTimeClient.start(address, "80", "82", "83");
        BufferedReader reader =
                new BufferedReader(new InputStreamReader(process.getInputStream()));

        String line;
        while ((line = reader.readLine()) != null) {
            System.out.println(line);
        }
        process.waitFor();
        process.destroy();

    }
}