java - 使一个 JPopupMenu 实际上弹出

Question

我有一个JFrame看起来像一个典型的聊天框。为了连接和断开与服务器的连接，我实现了 aJPopupMenu并将 a 添加MouseListener到主窗口。
但是弹出菜单不会出现。

主窗口中的各种 JComponents：

JTextArea在一个JScrollPane

JTextField输入消息

Send按钮

JScrollPane并ArrayList显示用户

无论您右键单击何处，都应该出现弹出窗口。无论是在JTextArea输入消息的字段上还是字段上。
我要向哪些所有组件添加侦听器，我要添加什么侦听器？

代码

变量：

    private static A_Chat_Client chatClient;
    public static String userName = "Anonymous";

//------------------------------------------------------------------------------
    public static JFrame mainFrame = new JFrame();
    public static JTextArea textArea = new JTextArea(30,30);
    public static JScrollPane pane = new JScrollPane(textArea);
    public static JTextField message = new JTextField(10);
    public static JButton send = new JButton("Send");

    public static JPopupMenu popup = new JPopupMenu();
    public static JMenuItem connect = new JMenuItem("Connect");
    public static JMenuItem disconnect = new JMenuItem("Disconnect");
    public static JMenuItem help = new JMenuItem("Help");

    public static JList usersOnline = new JList();
    public static JScrollPane userPane = new JScrollPane(usersOnline);  

主要方法

public static void main(String[] args) {
        buildMainWindow();
        initialize();
        addListeners();
        popup.show(mainFrame, 0, 0); //forcefully popup
    }  

添加监听器（）

public static void addListeners(){

        mainFrame.addMouseListener(new MouseHandler());

        send.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e){
                actionSend();
            }
        });
        connect.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e){
                actionConnect();
            }
        });
        disconnect.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e){
                actionDisconnect();
            }
        });
        help.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e){
                actionHelp();
            }
        });
    }  

类 MouseHandler

private static class MouseHandler extends MouseAdapter{
        @Override
        public void mouseClicked(MouseEvent e){
            if(e.isPopupTrigger()){
                popup.show(mainFrame, e.getX(), e.getY());
            }
        }
    }

Answer 1

您可以使用附加AWTEventListener到主事件队列Toolkit#addAWTEventListener

然后，您需要检查您收到的事件类型并检查它是否是弹出事件。

public class TestGlobalPopup {

    public static void main(String[] args) {
        new TestGlobalPopup();
    }

    public TestGlobalPopup() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            Toolkit.getDefaultToolkit().addAWTEventListener(new AWTEventListener() {
                @Override
                public void eventDispatched(AWTEvent event) {
                    if (event instanceof MouseEvent) {
                        MouseEvent me = (MouseEvent) event;
                        if (me.isPopupTrigger()) {
                            Component component = me.getComponent();
                            JPopupMenu popup = new JPopupMenu();
                            popup.add(new JLabel("Clicked on " + component.getClass().getName()));
                            popup.show(component, me.getX(), me.getY());
                        }
                    }
                }
            }, AWTEvent.MOUSE_EVENT_MASK);

            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridx = 0;
            gbc.gridy = 0;
            add(new JLabel("Label: "), gbc);
            gbc.gridx++;
            add(new JTextField(10), gbc);

            gbc.gridy++;
            gbc.gridx = 0;
            gbc.gridwidth = 2;
            add(new JScrollPane(new JTextArea(5, 20)), gbc);
        }

    }

}