有选择地将事件分派给弹出窗口的子项

Question

我正在尝试创建一个摆动弹出窗口，它将所有键盘事件转发到其中的文本字段，并将所有鼠标滚动事件转发到其中的 JScrollPane。我想出了这段代码，它覆盖了一些 processXXXEvent 方法，但是这种覆盖没有任何效果（您必须单击文本字段来键入并将鼠标移到 JScrollPane 上才能滚动它。

import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseWheelEvent;
import java.util.Random;

public class T extends JPanel {

    private final JTextField tf;
    private final JScrollPane sv;

    T() {
        this.tf = new JTextField();
        this.tf.setPreferredSize(new Dimension(100, 30));
        var lv = new JList<String>();
        lv.setListData(new String[] {"A", "B", "C", "D", "A", "B", "C", "D", "A", "B", "C", "D"});
        this.sv = new JScrollPane(lv);
        add(this.sv);
        add(this.tf);
    }

    @Override
    protected void processKeyEvent(KeyEvent e) {
        if (e.getKeyCode() == KeyEvent.VK_ENTER) {
            this.setVisible(false);
        } else {
            this.tf.dispatchEvent(e);
        }
    }

    @Override
    protected void processMouseWheelEvent(MouseWheelEvent e) {
        this.sv.dispatchEvent(e);
    }

    static JPopupMenu popup;

    static void showPopup(JFrame frame) {
        popup = new JPopupMenu();
        popup.add(new T());
        popup.show(frame, 0 ,0);
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("HelloWorldSwing");
        frame.setPreferredSize(new Dimension(200, 200));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setBackground(Color.GRAY);

        var b = new JButton("CLICK");
        b.setPreferredSize(new Dimension(100, 100));
        b.addMouseListener(new MouseListener() {
            @Override
            public void mouseClicked(MouseEvent mouseEvent) {
                showPopup(frame);
            }
            @Override
            public void mousePressed(MouseEvent mouseEvent) {}
            @Override
            public void mouseReleased(MouseEvent mouseEvent) {}
            @Override
            public void mouseEntered(MouseEvent mouseEvent) {}
            @Override
            public void mouseExited(MouseEvent mouseEvent) {}
        });
        frame.add(b);

        frame.pack();
        frame.setVisible(true);
    }
}

如何实现这种行为？

Answer 1

您的面板既没有实现也没有添加任何KeyListener 或MouseWheelListener。因此，您实现的用于覆盖事件处理的方法永远不会被调用。

这是您的 T 课程的简短 sn-p，应该适合您：

T() {
    tf = new JTextField();
    tf.setPreferredSize(new Dimension(100, 30));
    JList lv = new JList<String>();
    lv.setListData(new String[] { "A", "B", "C", "D", "A", "B", "C", "D", "A", "B", "C", "D" });
    sv = new JScrollPane(lv);
    add(sv);
    add(tf);
    setFocusable(true);
    addMouseWheelListener(new MouseAdapter() { // this will react to the scrolling
        public void mouseWheelMoved(MouseWheelEvent e) {
            sv.dispatchEvent(e);
        }
    });
    addKeyListener(new KeyAdapter() { // this reacts to the key strokes
        public void keyTyped(KeyEvent e) {
            if (e.getKeyCode() == KeyEvent.VK_ENTER) {
                popup.setVisible(false);
            } else {
                tf.dispatchEvent(e);
            }
        }
    });
}