Java键绑定

Question

我需要绑定所有箭头键以执行相同的功能，但是每次获取按下哪个键时。目前我只有通过以下方式按下向右箭头键时才有

DoneImg.getInputMap(JLabel.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "UpArrow");

Action MvRight = new AbstractAction()
{
     public void actionPerformed(ActionEvent e)
     {
           //Do whatever here
     }
};
DoneImg.getActionMap().put("RightArrow", MvRight);

但是我需要这样的东西

DoneImg.getInputMap(JLabel.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0), "RightArrow");
     DoneImg.getInputMap(JLabel.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0), "LeftArrow");
     DoneImg.getInputMap(JLabel.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0), "DownArrow");
     DoneImg.getInputMap(JLabel.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "UpArrow");

     Action MvAll = new AbstractAction()
         {
                 public void actionPerformed(ActionEvent e)
              {
                  if (e.keypressed == "LeftArrow")
                         {System.out.println("The left arrow was pressed!");}
                  if (e.keypressed == "RightArrow")
                         {System.out.println("The right arrow was pressed!");}
                  //and so forth
              }
                 };
     DoneImg.getActionMap().put("RightArrow", MvAll);
     DoneImg.getActionMap().put("LeftArrow", MvAll);
     DoneImg.getActionMap().put("UpArrow", MvAll);
     DoneImg.getActionMap().put("DownArrow", MvAll);

Answer 1

您要问的实际上是违反直觉的，并且违背了键绑定API的设计。

目的是为每个按键提供单个工作单元。在我看来，这建议您应为每个箭头键分别执行操作。

它使您更容易遵循逻辑，进行更改，根据需要规避操作。

但是我是谁呢？

如果看不到它，一种简单的方法就是为每个动作分配一个“命令”，然后在actionPerformed触发该动作时可以进行询问。

public TestKeyBindings02() {
    JPanel panel = new JPanel();
    InputMap im = panel.getInputMap(JPanel.WHEN_IN_FOCUSED_WINDOW);
    ActionMap am = panel.getActionMap();

    im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0), "RightArrow");
    im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0), "LeftArrow");
    im.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "UpArrow");
    im.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0), "DownArrow");

    am.put("RightArrow", new ArrowAction("RightArrow"));
    am.put("LeftArrow", new ArrowAction("LeftArrow"));
    am.put("UpArrow", new ArrowAction("UpArrow"));
    am.put("DownArrow", new ArrowAction("DownArrow"));
}

public class ArrowAction extends AbstractAction {

    private String cmd;

    public ArrowAction(String cmd) {
        this.cmd = cmd;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (cmd.equalsIgnoreCase("LeftArrow")) {
            System.out.println("The left arrow was pressed!");
        } else if (cmd.equalsIgnoreCase("RightArrow")) {
            System.out.println("The right arrow was pressed!");
        } else if (cmd.equalsIgnoreCase("UpArrow")) {
            System.out.println("The up arrow was pressed!");
        } else if (cmd.equalsIgnoreCase("DownArrow")) {
            System.out.println("The down arrow was pressed!");
        }
    }
}