java基于多线程的端口扫描程序

可以使用Java的Socket类和多线程技术来实现端口扫描程序。具体实现可以参考以下代码：

import java.net.*;
import java.util.concurrent.*;

public class PortScanner {
    public static void main(String[] args) {
        String host = "localhost";
        int timeout = 200;
        ExecutorService executor = Executors.newFixedThreadPool(20);
        for (int port = 1; port <= 65535; port++) {
            executor.execute(new PortScannerThread(host, port, timeout));
        }
        executor.shutdown();
        try {
            executor.awaitTermination(1, TimeUnit.DAYS);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

class PortScannerThread implements Runnable {
    private String host;
    private int port;
    private int timeout;

    public PortScannerThread(String host, int port, int timeout) {
        this.host = host;
        this.port = port;
        this.timeout = timeout;
    }

    @Override
    public void run() {
        try {
            Socket socket = new Socket();
            socket.connect(new InetSocketAddress(host, port), timeout);
            System.out.println("Port " + port + " is open");
            socket.close();
        } catch (Exception e) {
            // ignore
        }
    }
}

这个程序会扫描本地主机的所有端口，如果某个端口是开放的，就会输出"Port [port] is open"。可以根据需要修改host和timeout参数。