Question

我有一个JFrame，在此JFrame内有两个JPanel。当我按下一个键时，他们都必须听这个关键事件并采取行动。我想接受所有键盘事件，并将它们传递给JPanel两个。你知道怎么做吗？

编辑：由于他们必须做不同的事情，我需要两个不同的听众，抱歉没有具体。

Edit2：我制作了一个简单的代码来向您展示问题。当我按下向上键时，显示的JPanel都必须改变它们的字符串;在这段代码中，只有其中一个实际上有所反应！

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;

/**
*
 * @author antonioruffolo
 */
public class TwoPanelsTest extends JFrame {

public TwoPanelsTest() {

    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setResizable(false);
    setSize(800, 600);

    PanelTest panelTest1= new PanelTest();
    PanelTest panelTest2= new PanelTest();

    GridBagLayout layout= new GridBagLayout();
    this.setLayout(layout);

    GridBagConstraints c = new GridBagConstraints();

    c.ipadx = 220;
    c.ipady = 390;
    c.insets.right= 0;
    c.insets.left=30;
    layout.setConstraints(panelTest1, c);
    this.add(panelTest1);

    layout.setConstraints(panelTest2, c);
    c.ipadx = 220;
    c.ipady = 390;
    c.insets.right=250;
    c.insets.left=50;
    this.add(panelTest2);


    setVisible(true);
    setLocationRelativeTo(null);
    setTitle("Test");
    setFocusable(false);
}

private class PanelTest extends JPanel{

    private String string="I'm not called by the event";
    private InputMap inputmap;
    private ActionMap actionmap;

    public PanelTest(){
        setFocusable(false);
        setDoubleBuffered(true);

        this.setBackground(Color.WHITE);
        inputmap = getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
        inputmap.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "up");
        actionmap = getActionMap();
        actionmap.put("up", new ActionController(this));
    }

    public void setString(String string){
        this.string=string;
    }

    @Override
    public void paintComponent( Graphics g){
        super.paintComponent(g);

        Font infoFont= new Font("OCR A Std", Font.BOLD, 10);
        g.setFont(infoFont);
        g.drawString(string, 10, 50);
    }
}//PanelTest

private class ActionController extends AbstractAction{

    private PanelTest panel;

    public ActionController (PanelTest panel){
        this.panel=panel;
    }

    @Override
    public void actionPerformed(ActionEvent ae) {
        panel.setString("Action performed");
        panel.repaint();
    }

}

public static void main(String[] args) {
    TwoPanelsTest t = new TwoPanelsTest();
}
}

Answer 1

使用Key Bindings代替KeyListener，并为每个小组设置不同的Action。通过使用WHEN_ANCESTOR_OF_FOCUSED_COMPONENT输入映射，两个面板都可以响应。

附录：由于搜索在找到密钥的有效绑定后结束，因此下面的示例将事件转发<{em>}到List<MyPanel>的元素，每个元素都可以通过可用Action。

import java.awt.EventQueue; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.KeyEvent; import java.util.Arrays; import java.util.List; import javax.swing.AbstractAction; import javax.swing.Action; import javax.swing.BorderFactory; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.KeyStroke; /** @see http://stackoverflow.com/q/10011564/230513 */ public class TwoPanelsTest extends JFrame { private MyPanel one = new MyPanel("One"); private MyPanel two = new MyPanel("Two"); private List<MyPanel> list = Arrays.asList(one, two); public TwoPanelsTest() { super("TwoPanelsTest"); this.setDefaultCloseOperation(EXIT_ON_CLOSE); JPanel panel = new JPanel(new GridLayout(0, 1, 10, 10)); panel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10)); panel.add(one); panel.add(two); panel.getInputMap(JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT) .put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "up"); panel.getActionMap().put("up", new AbstractAction() { @Override public void actionPerformed(ActionEvent e) { for (MyPanel panel : list) { panel.getAction().actionPerformed(e); } } }); this.add(panel); this.pack(); this.setLocationRelativeTo(null); this.setVisible(true); } private static class MyPanel extends JPanel { private String string = " will be updated though its action."; private Action action = new UpdateAction(this); private String name; private JLabel label; public MyPanel(String name) { this.name = name; this.label = new JLabel(name + string, JLabel.CENTER); this.setLayout(new GridLayout()); this.setFocusable(true); this.add(label); } public Action getAction() { return action; } private void update() { label.setText(name + ": " + System.nanoTime()); } private static class UpdateAction extends AbstractAction { private MyPanel panel; public UpdateAction(MyPanel panel) { this.panel = panel; } @Override public void actionPerformed(ActionEvent ae) { panel.update(); } } } public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { @Override public void run() { TwoPanelsTest t = new TwoPanelsTest(); } }); } }

Answer 2

其中一种方法是使用SwingUtilities for Java6中的方法（通知SwingUtilities for Java7进行了一些更改，但在这种情况下不重要）可以重定向，分发来自{{Standard Swing Listeners的多个事件。 3}}，从一个容器到另一个容器的简单example about redirect mouse events，

Answer 3

您应该创建一个XXListener实现，并将.addXXListener的侦听器添加到您需要的所有组件中。

Answer 4

您可以使用观察者模式。 http://en.wikipedia.org/wiki/Observer_pattern

MyKeyEventListener listener = new MyKeyEventListener();
JPanel one = new JPanel();
one.addKeyListener(listener);//method might be wrong
JPanel two = new JPanel();
two.addKeyListener(listener);
listener.addObserver(one);
listener.addObserver(two);

如何让两个JPanels听同一个事件？

4 个答案: