如何用Java进行TCP端口扫描 Java扫描主机开放端口实例

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.UnknownHostException;

public class PortScanner {

    /**
     * 检查指定主机和端口是否开放
     * @param host 目标主机IP或域名
     * @param port 目标端口
     * @param timeout 连接超时时间（毫秒）
     * @return 如果端口开放返回true，否则返回false
     */
    public static boolean isPortOpen(String host, int port, int timeout) {
        try (Socket socket = new Socket()) { // 使用try-with-resources确保socket关闭
            // 尝试连接到目标地址和端口
            socket.connect(new InetSocketAddress(host, port), timeout);
            return true; // 连接成功，端口开放
        } catch (IOException e) {
            // 连接失败，端口可能关闭或被过滤
            // System.err.println("Error checking port " + port + ": " + e.getMessage());
            return false;
        }
    }

    public static void main(String[] args) {
        String targetHost = "localhost"; // 目标主机，可以是IP地址或域名
        int startPort = 1;
        int endPort = 1024; // 扫描常见端口范围
        int timeout = 200; // 连接超时时间，单位毫秒

        System.out.println("开始扫描 " + targetHost + " 的端口 " + startPort + " 到 " + endPort + "...");

        for (int port = startPort; port <= endPort; port++) {
            if (isPortOpen(targetHost, port, timeout)) {
                System.out.println("端口 " + port + " 是开放的。");
            } else {
                // System.out.println("端口 " + port + " 是关闭的或被过滤。");
            }
        }
        System.out.println("扫描完成。");
    }
}

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.*;

public class ConcurrentPortScanner {

    public static class PortScanTask implements Callable<Integer> {
        private final String host;
        private final int port;
        private final int timeout;

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

        @Override
        public Integer call() throws Exception {
            try (Socket socket = new Socket()) {
                socket.connect(new InetSocketAddress(host, port), timeout);
                return port; // 连接成功，返回端口号
            } catch (IOException e) {
                // 连接失败，不返回端口号
                return null;
            }
        }
    }

    public static void main(String[] args) {
        String targetHost = "localhost";
        int startPort = 1;
        int endPort = 65535; // 扫描全部端口，但实际中可能只扫常用端口
        int timeout = 200; // 连接超时时间，单位毫秒
        int numThreads = 50; // 线程池大小，根据网络和CPU情况调整

        // 创建一个固定大小的线程池
        ExecutorService executor = Executors.newFixedThreadPool(numThreads);
        List<Future<Integer>> futures = new ArrayList<>();

        long startTime = System.currentTimeMillis();
        System.out.println("开始并发扫描 " + targetHost + " 的端口 " + startPort + " 到 " + endPort + "...");

        for (int port = startPort; port <= endPort; port++) {
            PortScanTask task = new PortScanTask(targetHost, port, timeout);
            futures.add(executor.submit(task)); // 提交任务并获取Future对象
        }

        List<Integer> openPorts = new ArrayList<>();
        for (Future<Integer> future : futures) {
            try {
                Integer port = future.get(); // 阻塞直到任务完成并获取结果
                if (port != null) {
                    openPorts.add(port);
                }
            } catch (InterruptedException | ExecutionException e) {
                System.err.println("任务执行异常: " + e.getMessage());
            }
        }

        // 关闭线程池
        executor.shutdown();
        try {
            // 等待所有任务完成，最多等待1分钟
            if (!executor.awaitTermination(1, TimeUnit.MINUTES)) {
                System.err.println("部分任务未能及时完成。");
            }
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            System.err.println("等待线程池终止时被中断。");
        }

        long endTime = System.currentTimeMillis();
        System.out.println("扫描完成。耗时: " + (endTime - startTime) + " ms");
        System.out.println("开放端口: " + openPorts);
    }
}