按键绑定分开按键检测

Question

我的键绑定有问题：我编写了此程序，但是它只能检测到向下箭头。 如何获得分别读取按键的信息？ 我做错了什么？

import java.awt.*;
import java.awt.event.*;
import java.awt.event.ActionEvent;
import javax.swing.*;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.InputMap;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;

public class KeysExample extends JFrame{

    public static void main(final String args[]){
        final JFrame frame = new JFrame("Frame Key");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        Action actionSpace = new AbstractAction(){
            public void actionPerformed(ActionEvent actionSpaceEvent){
                Component temporaryLostComponent = null;
                JOptionPane.showMessageDialog(temporaryLostComponent, "Pressed Spacebar");
            }
        };

        Action actionRight = new AbstractAction(){
            public void actionPerformed(ActionEvent actionRightEvent){
                Component temporaryLostComponent = null;
                JOptionPane.showMessageDialog(temporaryLostComponent, "Pressed Right Arrow");
            }
        };

        Action actionLeft = new AbstractAction(){
            public void actionPerformed(ActionEvent actionLeftEvent){
                Component temporaryLostComponent = null;
                JOptionPane.showMessageDialog(temporaryLostComponent, "Pressed Left Arrow");
            }
        };

        Action actionUp = new AbstractAction(){
            public void actionPerformed(ActionEvent actionUpEvent){
                Component temporaryLostComponent = null;
                JOptionPane.showMessageDialog(temporaryLostComponent, "Pressed Up Arrow");
            }
        };

        Action actionDown = new AbstractAction(){
            public void actionPerformed(ActionEvent actionDownEvent){
                Component temporaryLostComponent = null;
                JOptionPane.showMessageDialog(temporaryLostComponent, "Pressed Down Arrow");
            }
        };

        JPanel content = (JPanel) frame.getContentPane();
        KeyStroke space = KeyStroke.getKeyStroke("SPACE");
        KeyStroke right = KeyStroke.getKeyStroke("RightArrow");
        KeyStroke left = KeyStroke.getKeyStroke("LeftArrow");
        KeyStroke up = KeyStroke.getKeyStroke("UpArrow");
        KeyStroke down = KeyStroke.getKeyStroke("DownArrow");

        InputMap inputMap = content.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
        inputMap.put(space, "OPEN");
        inputMap.put(right, "OPEN");
        inputMap.put(left, "OPEN");
        inputMap.put(up, "OPEN");
        inputMap.put(down, "OPEN");
        content.getActionMap().put("OPEN", actionSpace);
        content.getActionMap().put("OPEN", actionRight);
        content.getActionMap().put("OPEN", actionLeft);
        content.getActionMap().put("OPEN", actionUp);
        content.getActionMap().put("OPEN", actionDown);

        frame.setSize(300, 300);
        frame.setVisible(true);
    }
}

另外，我知道代码有些扩展，有些行可能是多余的。 我是一个初学者，所以我仍然有很多要学习的知识。 我还意识到，在用JFrame创建的窗口中什么也没显示，以后还会出现。 知道我需要解决这个问题。

Answer 1

但它只会检测到向下箭头。

这是因为您将所有笔画都分配给了“ OPEN”关键字，而最后分配给“ OPEN”关键字的动作是downAction。

每个InputMap / ActionMap配对必须具有唯一的关键字名称（例如“ UP”，“ DOWN”，“ RIGHT” ...）。

KeyStroke.getKeyStroke("");

另外，您不能只为KeyStroke组成字符串。 您必须使用在KeyEvent类中定义的名称：

KeyEvent.VK_UP becomes "UP"
KeyEvent.VK_DOWN becomes "DOWN"

等等..

阅读API以获取字符串的确切格式。

您可能想查看使用键盘运动的更多信息和示例。