java - Java Swing FocusListener的MVC实现

Question

我正在尝试使用 MVC 架构模式构建一个简单的 Java Swing 应用程序。我所做的是在我的 View 中创建用户界面组件(作为私有(private)的)，并具有返回组件的公共(public)方法。然后 Controller 调用这些方法，通过它们我可以为事件/ Action 监听器编写方法。下面是一个示例:

查看:

private JButton btnAdd;

    public JButton getBtnAdd(){
        return btnAdd;
    }

控制:

myGuiFrame gui = new myGuiFrame();


        //on add button clicked
    gui.getBtnAdd().addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            //calls to model
        }
    });

这个实现是否正确？

如果是这样，那么我遇到了 FocusListeners 的问题。当我在 View 中创建 FocusListener 时，会在 View 中创建 focusLost 和 focusGained 方法。

private FocusListener l;

someComponent.addFocusListener(l);

        l = new FocusListener() {

            @Override
            public void focusLost(FocusEvent e) {
                // TODO Auto-generated method stub
            }

            @Override
            public void focusGained(FocusEvent e) {
                // TODO Auto-generated method stub

            }
        };

我希望所有事件处理程序都在我的 Controller 中。我的问题是......有没有一种方法可以从我的 Controller 调用/声明 focusLost 和 focusGained 方法？我试图将 FocusListener 定义为公共(public)的，以便我可以在我的 Controller 中定义它:

查看:

public FocusListener l;
public someComponentType someComponent;

Controller :

gui.l = new FocusListener() {
    @Override
    public void focusLost(FocusEvent e) {
        // TODO Auto-generated method stub

}

@Override
public void focusGained(FocusEvent e) {
    // TODO Auto-generated method stub
    gui.someComponent.addFocusListener(gui.l);

    }   

};

但这不起作用。

是否可以从 Controller 处理 FocusEvents？

编辑:

天哪，我的错。不太明白罗宾的意思。我太执着于在某处明确定义 FocusListener。一个简单的:

    gui.getTextFieldEmployeeCode().addFocusListener(new FocusListener() {

        @Override
        public void focusLost(FocusEvent e) {
            // TODO Auto-generated method stub

        }

        @Override
        public void focusGained(FocusEvent e) {
            // TODO Auto-generated method stub
            System.out.println("YES!!!");
        }
    });

在 Controller 中可以按照我计划的方式正常工作，尽管我非常喜欢 nIcE cOw 的处理方式。出于好奇，是否存在在 Swing 应用程序上实现 MVC 的标准或被广泛接受的方式？

Answer 1

据我了解，你的做法是这样的。更好的是，我更喜欢匿名类，它们尊重封装的概念。在这里尝试一下这段代码，看看你能掌握什么:

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

public class View
{
    private JButton focusButton;
    private JButton spareButton;

    private void createAndDisplayGUI()
    {
        JFrame frame = new JFrame("VIEW");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

        JPanel contentPane = new JPanel();
        contentPane.setLayout(new FlowLayout(FlowLayout.LEFT, 5, 5));

        focusButton = new JButton("GAINED/LOST");
        focusButton.addFocusListener(new ButtonController(this));

        spareButton = new JButton("SPARE");
        spareButton.setOpaque(true);
        spareButton.addActionListener(new ButtonController(this));
        spareButton.addFocusListener(new ButtonController(this));

        contentPane.add(focusButton);
        contentPane.add(spareButton);

        frame.setContentPane(contentPane);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public JButton getFocusButton()
    {
        return focusButton;
    }

    public JButton getSpareButton() 
    {
        return spareButton;
    }

    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                new View().createAndDisplayGUI();
            }
        });
    }
}

class ButtonController implements FocusListener, ActionListener
{
    private View view;
    private JButton focusButton;
    private JButton spareButton;

    public ButtonController(View v)
    {
        view = v;
        focusButton = view.getFocusButton();
        spareButton = view.getSpareButton();
    }

    public void actionPerformed(ActionEvent ae)
    {
        JButton button = (JButton) ae.getSource();

        if (button == spareButton)
        {
            spareButton.setBackground(Color.BLUE);
            focusButton.setEnabled(true);
        }
    }

    public void focusGained(FocusEvent fe)
    {
        JButton button = (JButton) fe.getSource();

        if (button == focusButton)
        {
            focusButton.setEnabled(true);
        }
        else if (button == spareButton)
        {
            spareButton.setBackground(Color.WHITE);
        }
    }

    public void focusLost(FocusEvent fe)
    {
        JButton button = (JButton) fe.getSource();

        if (button == focusButton)
        {
            focusButton.setEnabled(false);
        }
        else if (button == spareButton)
        {
            spareButton.setBackground(Color.DARK_GRAY.darker());
        }
    }
}

如果您对 getters/setters 和四处发送引用感到恼火，另一种方法是定义一个内部类，如下所示(前一个示例的简单解决方法):

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

public class View
{
    private JButton focusButton;
    private JButton spareButton;

    private void createAndDisplayGUI()
    {
        JFrame frame = new JFrame("VIEW");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

        JPanel contentPane = new JPanel();
        contentPane.setLayout(new FlowLayout(FlowLayout.LEFT, 5, 5));

        focusButton = new JButton("GAINED/LOST");
        focusButton.addFocusListener(new ButtonController());

        spareButton = new JButton("SPARE");
        spareButton.setOpaque(true);
        spareButton.addActionListener(new ButtonController());
        spareButton.addFocusListener(new ButtonController());

        contentPane.add(focusButton);
        contentPane.add(spareButton);

        frame.setContentPane(contentPane);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    private class ButtonController implements FocusListener, ActionListener
    {

        public void actionPerformed(ActionEvent ae)
        {
            JButton button = (JButton) ae.getSource();

            if (button == spareButton)
            {
                spareButton.setBackground(Color.BLUE);
                focusButton.setEnabled(true);
            }
        }

        public void focusGained(FocusEvent fe)
        {
            JButton button = (JButton) fe.getSource();

            if (button == focusButton)
                focusButton.setEnabled(true);
            else if (button == spareButton)
                spareButton.setBackground(Color.WHITE);
        }

        public void focusLost(FocusEvent fe)
        {
            JButton button = (JButton) fe.getSource();

            if (button == focusButton)
                focusButton.setEnabled(false);
            else if (button == spareButton)
                spareButton.setBackground(Color.DARK_GRAY.darker());
        }
    }

    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                new View().createAndDisplayGUI();
            }
        });
    }
}