java - 父 JPanel - 如何监听子 JPanel 组件生成的事件？

Question

这个问题已经有答案了:

Adding ActionListener to a Panel - Panel implements ActionListener vs Panel HAS A ActionListener (2 个回答)

已关闭 10 年前。

我制作了一个 JPanel Child，其中包含几个单选按钮。每当单击单选按钮时，我也希望从子级生成一个 ActionEvent。此操作事件应“包含”对实际生成事件的按钮的引用。

此子级将用作另一个 JPanel 父级中的组件，该父级将监听来自子级的事件，而不是监听各个单选按钮。

我该怎么做？

到目前为止的代码 -

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class RadioListener extends JPanel implements ActionListener{

public static final String id = "id";

public RadioListener(){

    for(int i = 1; i < 5; i++){
        JRadioButton jrb = new JRadioButton(i + "", false);
        jrb.putClientProperty(id, i);
        this.add(jrb);
        jrb.addActionListener(this);

    }

}


public void actionPerformed(ActionEvent e){

    JRadioButton jrb = (JRadioButton) e.getSource(); 
    Integer id = (Integer) jrb.getClientProperty(RadioListener.id);
    System.out.println("id " + id);

}


public static void main(String[]args){

    JFrame frame = new JFrame("Radio buttons");
    frame.getContentPane().setLayout(new FlowLayout());
    frame.setSize(400, 100);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().add(new RadioListener());
    frame.setVisible(true);


}

}

Answer 1

我建议为组件提供充当其他感兴趣方注册兴趣的代理的功能。

这意味着您不需要公开其他组件不应调用或有权访问的方法/组件。

您还应该为监听器使用内部类，因为它们将防止暴露其他人不应访问的其他方法

public class ProxyActionListener extends JPanel {

    public static final String id = "id";
    private List<JRadioButton> buttons;

    public ProxyActionListener() {

        buttons = new ArrayList<>(25);
        ActionHandler actionHandler = new ActionHandler();

        for (int i = 1; i < 5; i++) {
            JRadioButton jrb = new JRadioButton(i + "", false);
            jrb.putClientProperty(id, i);
            this.add(jrb);
            jrb.addActionListener(actionHandler);
            buttons.add(jrb);

        }

    }

    public void addActionListener(ActionListener listener) {
        for (JRadioButton btn : buttons) {
            btn.addActionListener(listener);
        }
    }

    public void removeActionListener(ActionListener listener) {
        for (JRadioButton btn : buttons) {
            btn.removeActionListener(listener);
        }
    }

    public static void main(String[] args) {

        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                ProxyActionListener pal = new ProxyActionListener();
                pal.addActionListener(new ActionListener() {
                    @Override
                    public void actionPerformed(ActionEvent e) {
                        JRadioButton jrb = (JRadioButton) e.getSource();
                        Integer id = (Integer) jrb.getClientProperty(ProxyActionListener.id);
                        System.out.println("Proxy- id " + id);
                    }
                });

                JFrame frame = new JFrame("Radio buttons");
                frame.getContentPane().setLayout(new FlowLayout());
                frame.setSize(400, 100);
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.getContentPane().add(pal);
                frame.setVisible(true);
            }
        });
    }

    protected class ActionHandler implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {

            JRadioButton jrb = (JRadioButton) e.getSource();
            Integer id = (Integer) jrb.getClientProperty(ProxyActionListener.id);
            System.out.println("id " + id);

        }
    }
}