代码之家 › 专栏 › 技术社区 › Eugene

当我单击不相关的按钮时,为什么我的密钥绑定无法工作?

key-bindings awt focus swing java

Eugene · 技术社区 · 10 年前

我创建了一个简单的演示。如果您在主面板上触发特定按键Stroke事件,将显示消息“a is typed”。然而,当我按下主面板下面的按钮后,它就不起作用了。下面是KeybindingTest类及其内部类:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class KeybindingTest {
    private JFrame frame;
    private MainPanel mainPanel;
    private ButtonPanel buttonPanel;
    public static void main(String[] args) {
        KeybindingTest test = new KeybindingTest();
        test.createUI();
    }

    public void createUI(){
        frame = new JFrame("Keybing Test");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        mainPanel = new MainPanel();
        buttonPanel = new ButtonPanel();
        frame.add(mainPanel,BorderLayout.CENTER);
        frame.add(buttonPanel,BorderLayout.SOUTH);
        KeybindingListener.getInstance().keybinding(mainPanel);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    @SuppressWarnings("serial")
    class MainPanel extends JPanel{
        @Override
        public Dimension getPreferredSize() {
            // TODO Auto-generated method stub
            return new Dimension(400, 300);
        }
    }

    @SuppressWarnings("serial")
    class ButtonPanel extends JPanel{
        public ButtonPanel(){
            setBackground(Color.green);
            JButton enableButton = new JButton("enable");
            enableButton.addActionListener(new EnableButtonListener());
            JButton disableButton = new JButton("disable");
            disableButton.addActionListener(new DisableButtonListener());
            add(enableButton);
            add(disableButton);
        }
    }

    class EnableButtonListener implements ActionListener{
        @Override
        public void actionPerformed(ActionEvent e) {
            // TODO Auto-generated method stub
            System.out.println("enabled");
        }

    }

    class DisableButtonListener implements ActionListener{
        @Override
        public void actionPerformed(ActionEvent e) {
            // TODO Auto-generated method stub
            System.out.println("disabled");
        }

    }
}

下面是KeybindingListener类及其内部类:

import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;

import javax.swing.AbstractAction;
import javax.swing.JPanel;
import javax.swing.KeyStroke;

public class KeybindingListener {
    private static KeybindingListener keybindingListener;
    private final String mapKey = "a";

    private KeybindingListener(){
        //singleton
    }

    public static KeybindingListener getInstance(){
        if (keybindingListener == null) {
            keybindingListener = new KeybindingListener();
            return keybindingListener;
        }else {
            return keybindingListener;
        }
    }

    public void keybinding(JPanel mainPanel){
        mainPanel.getInputMap().put(KeyStroke.getKeyStroke(KeyEvent.VK_A , 0),mapKey);
        mainPanel.getActionMap().put(mapKey, new keyAction());
    }

    @SuppressWarnings("serial")
    class keyAction extends AbstractAction{

        @Override
        public void actionPerformed(ActionEvent e) {
            // TODO Auto-generated method stub
            System.out.println("a is typed");
        }

    }
}

提前感谢您的帮助。

1 回复 | 直到 10 年前

Community Egal 7 年前

如中所述 this answer , JComponent#getInputMap() 是一种方便的方法 JComponent#getInputMap(WHEN_FOCUSED) 。由于要将密钥绑定添加到 JPanel 这意味着您的小组必须专注于正确工作,这是不可能的。

您可以按原样将键绑定添加到面板中的所有组件,也可以按如下方式向面板添加键绑定:

public void keybinding(JPanel mainPanel){
    mainPanel.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_A , 0),mapKey);
    mainPanel.getActionMap().put(mapKey, new keyAction());
}

看见 How Key Bindings Work 为了更好地解释这件事。