Java ping服务器时，即使它处于联机状态，也表示它处于脱机状态？

我试图查看一些服务器是否在IP上的一系列端口上联机。因为某种原因，它总是说离线。我在另一个应用程序中尝试了ping方法，它可以完美地工作。我正在制作的这个应用程序是多线程的，但我不知道这是否会影响ping。这是我正在做的主要课程

public class Tools extends JFrame {

/**
 * 
 */
private static final long serialVersionUID = 1L;
private JPanel contentPane;
private JTextField textField;

public static String ip;
public static int port;
public static int startPort;
public static int lastPort;

public static JList<String> list;
public static JList<String> list_1;
public static JList<String> list_2;

public static DefaultListModel<String> model = new DefaultListModel<>();
public static DefaultListModel<String> model_1 = new DefaultListModel<>();
public static DefaultListModel<String> model_2 = new DefaultListModel<>();

public static Thread[] threads = new Thread[256];
private JButton btnStopBeforeIt;
private JTextField textField_1;
private JTextField textField_2;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                Tools frame = new Tools();
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the frame.
 */
public Tools() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 846, 694);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    contentPane.setLayout(null);

    textField = new JTextField();
    textField.setBounds(20, 11, 369, 50);
    contentPane.add(textField);
    textField.setColumns(10);

    JButton btnStart = new JButton("Start");
    btnStart.setBounds(399, 11, 89, 50);
    contentPane.add(btnStart);

    list = new JList<String>();
    list.setBounds(552, 88, 256, 557);
    contentPane.add(list);

    list_1 = new JList<String>();
    list_1.setBounds(20, 88, 256, 557);
    contentPane.add(list_1);

    list_2 = new JList<String>();
    list_2.setBounds(286, 88, 256, 557);
    contentPane.add(list_2);

    btnStopBeforeIt = new JButton("STOP BEFORE IT CRASHES UR COMPUTER");
    btnStopBeforeIt.setForeground(Color.RED);
    btnStopBeforeIt.setBounds(498, 0, 310, 31);
    contentPane.add(btnStopBeforeIt);

    textField_1 = new JTextField();
    textField_1.setBounds(498, 42, 86, 20);
    contentPane.add(textField_1);
    textField_1.setColumns(10);

    textField_2 = new JTextField();
    textField_2.setBounds(722, 42, 86, 20);
    contentPane.add(textField_2);
    textField_2.setColumns(10);

    JLabel lblRanges = new JLabel("Ranges");
    lblRanges.setFont(new Font("Tahoma", Font.PLAIN, 16));
    lblRanges.setBounds(622, 42, 68, 19);
    contentPane.add(lblRanges);

    JLabel lblStart = new JLabel("Start");
    lblStart.setBounds(527, 63, 46, 14);
    contentPane.add(lblStart);

    JLabel lblEnd = new JLabel("End");
    lblEnd.setBounds(757, 63, 46, 14);
    contentPane.add(lblEnd);

    btnStart.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            if(!textField.getText().equalsIgnoreCase("")){

                startPort = Integer.parseInt(textField_1.getText());
                lastPort = Integer.parseInt(textField_2.getText());

                port = startPort;

                ip = textField.getText();

                loadThreads();

                startThreads();

            }else{
                JOptionPane.showMessageDialog(null,"The IP address textbox cannot be left blank!", "Derpius Tools", JOptionPane.OK_OPTION);
            }
        }
    });

    btnStopBeforeIt.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            stopThreads();
        }
    });

}

public static void loadThreads(){
    for(int i = 0; i != 256; i++){
        threads[i] = new Thread(new Pinger());
    }
}

public static void startThreads(){
    for(int i = 0; i != 256; i++){
        threads[i].start();
    }
}

@SuppressWarnings("deprecation")
public static void stopThreads(){
    for(int i = 0; i != 256; i++){
        threads[i].stop();
    }
}
    }

---

你的问题不清楚实际问题是什么

如果线程报告服务器处于联机状态，但GUI显示为脱机状态，则可能是因为您正在非事件线程上更新Swing组件。您应该使用更新组件

更新

正如正确指出的，您正在默默地接受ping方法中的异常。打印堆栈跟踪可以更好地了解正在发生的情况

public static boolean serverIsOnline() { 
    try (Socket s = new Socket(Tools.ip, Tools.port)) {
        return true;
    } catch (IOException ex) {
        // log the exception here, at the very least:
        ex.printStackTrace();
    }
    return false;
}

---

有没有可能ping服务没有在服务器上运行，或者被防火墙或路由器阻止…澄清一下，你看到了吗。。。是在线的！或他离线了！在stdout上？或者你可能会得到一个异常…一个无声的异常

public static boolean serverIsOnline() { 
    try (Socket s = new Socket(Tools.ip, Tools.port)) {
        return true;
    } catch (IOException ex) {
        // log the exception here, at the very least:
        ex.printStackTrace();
    }
    return false;
}