java - 如何将参数传递给 KeyBinding 中的 AbstractAction？

Question

我有以下键绑定(bind):

    InputMap iMap = component.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
    ActionMap aMap = component.getActionMap();
    
    iMap.put(KeyStroke.getKeyStroke("shift LEFT"), "MOVE_LONG_LEFT");
    iMap.put(KeyStroke.getKeyStroke("LEFT"), "MOVE_LEFT");
    aMap.put("MOVE_LONG_LEFT", moveLeft);   // I WANT moveLeft TO RECEIVE 10 AS PARAMETER
    aMap.put("MOVE_LEFT", moveLeft);        // I WANT moveLeft TO RECEIVE 1 AS PARAMETER

我想在 ActionMap 中向 moveLeft 添加一个参数，例如(伪代码):

aMap.put("MOVE_LONG_LEFT", moveLeft, 10);
aMap.put("MOVE_LEFT", moveLeft, 1);

...

Action moveLeft = new AbstractAction(int steps) {
    @Override
    public void actionPerformed(ActionEvent e) {
        System.out.println("moved Left " + steps + " steps");
    }
};

是否可以在 KeyBindings 中传递参数？

Answer 1

How do I pass an arguments to an AbstractAction

将您的 Action 创建为内部类，然后您可以将参数保存为类的实例变量中:

class MoveAction extends AbstractAction 
{
    private int steps;

    public MoveAction(int steps)
    {
        this.steps = steps;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        System.out.println("moved Left " + steps + " steps");
    }
};

然后你使用这样的类:

aMap.put("MOVE_LONG_LEFT", new MoveAction(10)); 
aMap.put("MOVE_LEFT", new MoveAction(1));  

参见； Motion Using the Keyboard 。 MotionWithKeyBindings 示例演示了这种方法。