java - JButton 按下（不释放）

Question

我有一个非常小的 JButton，名为“b”，我想在点击时而不是在释放时做一些事情。我使用以下代码：

b.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e){
            //do some stuff
        }
    });

但我意识到，只要单击第一次按下然后释放，它就会执行我想要的操作。我怎么能这样做？谢谢

Answer 1

单击表示按钮已被按下和释放。单击按钮时触发单击事件，并且仅当释放鼠标时按钮仍处于武装状态（鼠标在按钮范围内）时才会触发。要处理按下事件，请使用低级MouseListener

btn.addMouseListener(new MouseListener() {

    @Override
    public void mousePressed(MouseEvent e) {
        //do some stuff
    }

    /*Override other methods*/

});

或者更好地使用MouseAdapter

btn.addMouseListener(new MouseAdapter() {

        @Override
        public void mousePressed(MouseEvent e) {
            //do some stuff
        }

        /*No need to override other methods, `MouseAdapter` already does it*/

    });

Answer 2

上面的答案只对鼠标事件做出反应，但是当它具有输入焦点时，可以使用空格键来切换按钮按下状态。对于完整的实现，请使用 MouseListener AND KeyListener。

b.addMouseListener(new MouseListener() {

    public void mouseClicked(MouseEvent e) {}
    public void mouseEntered(MouseEvent e) {}
    public void mouseExited(MouseEvent e) {}
    public void mousePressed(MouseEvent e) {
        doOnPressedAction();
    }
    public void mouseReleased(MouseEvent e) {
        doOnReleasedAction();
    }
});
b.addKeyListener(new KeyListener(){
    public void keyTyped(KeyEvent e) {}

    public void keyPressed(KeyEvent e) {
        if (sendButton.getModel().isPressed()) {
            doOnPressedAction();
        } else {
            // just in case it can happen that the button is released on
            // a key press action (maybe another controls key listener...)
            doOnReleasedAction();
        }
    }

    public void keyReleased(KeyEvent e) {
        doOnReleasedAction();
    }
});