Question

我试图这样做：在我的GUI中，我有一个带有自定义模型的JTable，而在GUI的其他部分，我有一个面板，我绘制一些箭头。我想＆＃34;同步这两个视图。所以，让我们说如果我的JTable中有5行，我将在箭头面板中绘制5个箭头。如果我修改行数，我必须有相同的行数。所以我试图使用Design Pattern Observer。

为简单起见，我尝试在一个文件中提供一个可计算的示例：我在第一个Panel（ButtonPanel）中创建了n个按钮，然后在第二个面板（LabelButton）中创建了n个标签。

问题是：如何使用DP Observer同步标签数量与标签数量

import java.awt.Color;
import java.awt.GridLayout;
import java.util.ArrayList;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.LineBorder;

interface Observer {
    public void update(Subject subject, int number);
}

interface Subject {
    public void addObserver(Observer observer);

    public void delObserver(Observer observer);

    public void notifyObservers();
}

class SynchronizeNumber implements Subject {
    private ArrayList<Observer> observers;

    private int numberSync;

    public SynchronizeNumber() {
        super();
        observers = new ArrayList<Observer>();

    }

    public SynchronizeNumber(int numberSync) {
        super();
        this.numberSync = numberSync;
        observers = new ArrayList<Observer>();

    }

    @Override
    public void addObserver(Observer observer) {
        observers.add(observer);

    }

    @Override
    public void delObserver(Observer observer) {
        observers.remove(observer);

    }

    @Override
    public void notifyObservers() {
        for (Observer o : observers) {
            o.update(this, this.numberSync);
        }
    }

    /**
     * @return the number
     */
    public int getNumberSync() {
        return numberSync;
    }

    /**
     * @param number
     *            the number to set
     */
    public void setNumberSync(int numberSync) {
        this.numberSync = numberSync;
        notifyObservers();
    }
}

class ButtonPanel extends JPanel implements Observer {

    private int numberButton;

    public ButtonPanel() {
        super();
    }

    public ButtonPanel(int numberButton) {
        this.numberButton = numberButton;
        for (int i = 1; i <= numberButton; i++)
            this.add(new JButton("" + i));
    }

    /**
     * @return the numberLabel
     */
    public int getNumberButton() {
        return numberButton;
    }

    /**
     * @param numberLabel
     *            the numberLabel to set
     */
    public void setNumberButton(int numberButton) {
        this.numberButton = numberButton;
    }

    @Override
    public void update(Subject subject, int number) {
        if (subject instanceof SynchronizeNumber) {
            SynchronizeNumber synchronizeNumber = (SynchronizeNumber) subject;
            numberButton = synchronizeNumber.getNumberSync();
            System.out.println("ButtonPanel, numberButton: " + numberButton);
        }
    }
}

class LabelPanel extends JPanel implements Observer {

    private int numberLabel;

    public LabelPanel() {
        super();
    }

    public LabelPanel(int numberLabel) {
        super();
        this.numberLabel = numberLabel;
        for (int i = 1; i <= numberLabel; i++)
            this.add(new JLabel("label numbe: " + i));
        this.setBorder(new LineBorder(Color.blue));
    }

    @Override
    public void update(Subject subject, int number) {
        if (subject instanceof SynchronizeNumber) {
            SynchronizeNumber synchronizeNumber = (SynchronizeNumber) subject;
            numberLabel = synchronizeNumber.getNumberSync();
            System.out.println("LabelPanel, numberLabel: " + numberLabel);
        }
    }

    /**
     * @return the numberLabel
     */
    public int getNumberLabel() {
        return numberLabel;
    }

    /**
     * @param numberLabel
     *            the numberLabel to set
     */
    public void setNumberLabel(int numberLabel) {
        this.numberLabel = numberLabel;
    }
}

public class Test {

    public static void main(String[] args) {
        JFrame f = new JFrame();
        f.setLayout(new GridLayout(2, 1));

        // create an subject synchronizeNumber
        SynchronizeNumber synchronizeNumber = new SynchronizeNumber();

        // set number to 1
        synchronizeNumber.setNumberSync(1);

        //create observers buttonPanel and labelPanel 
        ButtonPanel buttonPanel = new ButtonPanel(synchronizeNumber.getNumberSync());
        LabelPanel labelPanel = new LabelPanel(synchronizeNumber.getNumberSync());

        // add buttonPanel and labelPanel as observers
        synchronizeNumber.addObserver(buttonPanel);
        synchronizeNumber.addObserver(labelPanel);

        // make a change manually
        synchronizeNumber.setNumberSync(4);
        f.add(buttonPanel);
        f.add(labelPanel);
        f.setSize(400, 400);
        f.setLocationRelativeTo(null);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setVisible(true);
    }

}

编辑：我使用自己的DP Observer而不是API，因为无法进行多次扩展

Answer 1

我使用Observer模式，因为我认为这是最好的解决方案。

Swing是一个事件驱动的API，其行为非常类似于观察者模式，因为有订阅的事件和侦听器会监听这些事件。例如，JButton组件每次按下时都会调度ActionEvent，并通知订阅ActionListener发生的事情。

使用相同的原则，TableModel的责任是每次更改数据（添加/删除行，更新单元格等）时调度TableModelEvent并通知订阅的TableModelListener在这样的事件中。

您可以使用此事实来实现您的主要目标：

因此，假设我的JTable中有5行，我将绘制5个箭头箭头小组。

创建一个JPanel，可以根据需要绘制许多箭头。请参阅Performing Custom Painting课程。
将TableModelListener附加到TableModel，以便在插入/删除行时重新显示JPanel。

我有两个类，我希望两者之间存在最小的依赖关系类。

如果您遵循我的建议，您应该能够像这样创建一个独立且可重复使用的JPanel：

class MyCustomPanel extends JPanel {

    private int numberOfArrows = 0;

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g); // never forget to call super.paintComponent(g)
        Graphics graphics = g.create();
        int y = 10;
        for(int i = 0; i < numberOfArrows; i++) {                
            graphics.drawLine(10, y, getWidth() - 10, y); // instead of lines just draw your arrows
            y += 10;
        }
        graphics.dispose();
    }

    /**
     * Public method to set the number of arrows that has to be drawn.
     * @param arrows 
     */
    public void setNumberOfArrows(int arrows) {
        numberOfArrows = arrows;
        repaint();
    }

    @Override
    public Dimension getPreferredSize() {
        return isPreferredSizeSet() 
             ? super.getPreferredSize() : new Dimension(200,200);
    }
}

通过这种方式，您的面板可以独立地确定外部箭头的数量（它可以是表模型中的行数，列表中的元素数，固定值，您想要的任何值）。

Answer 2

我完全按照你的意愿实现了它：

import java.awt.Color;
import java.awt.GridLayout;
import java.util.ArrayList;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.LineBorder;

interface Observer {
    public void update(Subject subject, int number);
}

interface Subject {
    public void addObserver(Observer observer);

    public void delObserver(Observer observer);

    public void notifyObservers();
}

class SynchronizeNumber implements Subject {
    private ArrayList<Observer> observers;

    private int numberSync;

    public SynchronizeNumber() {
        super();
        observers = new ArrayList<Observer>();

    }

    public SynchronizeNumber(int numberSync) {
        super();
        this.numberSync = numberSync;
        observers = new ArrayList<Observer>();

    }

    @Override
    public void addObserver(Observer observer) {
        observers.add(observer);

    }

    @Override
    public void delObserver(Observer observer) {
        observers.remove(observer);

    }

    @Override
    public void notifyObservers() {
        for (Observer o : observers) {
            o.update(this, this.numberSync);
        }
    }

    /**
     * @return the number
     */
    public int getNumberSync() {
        return numberSync;
    }

    /**
     * @param number
     *            the number to set
     */
    public void setNumberSync(int numberSync) {
        this.numberSync = numberSync;
        notifyObservers();
    }
}

class ButtonPanel extends JPanel implements Observer {

    private int numberButton;

    public ButtonPanel() {
        super();
    }

    public ButtonPanel(int numberButton) {
        this.numberButton = numberButton;
        for (int i = 0; i < numberButton; i++)
            this.add(createButton(i));
    }

    /**
     * @return the numberLabel
     */
    public int getNumberButton() {
        return numberButton;
    }

    /**
     * @param numberLabel
     *            the numberLabel to set
     */
    public void setNumberButton(int numberButton) {
        this.numberButton = numberButton;
    }

    @Override
    public void update(Subject subject, int number) {
        if (subject instanceof SynchronizeNumber) {
            SynchronizeNumber synchronizeNumber = (SynchronizeNumber) subject;
            int diff = numberButton + (number - numberButton);
            // if diff and numberButton are equal do nothing
            if (diff < numberButton) {
                for (int i = numberButton - 1; i >= diff; i--) {
                    this.remove(this.getComponent(i));
                }
            } else if (diff > numberButton) {
                for (int i = numberButton; i < diff; i++) {
                    this.add(createButton(i));
                }
            }
            numberButton = number;
            System.out.println("ButtonPanel, numberButton: " + numberButton);
        }
    }

    private JButton createButton(int i) {
        return new JButton("" + ++i);
    }
}

class LabelPanel extends JPanel implements Observer {

    private int numberLabel;

    public LabelPanel() {
        super();
    }

    public LabelPanel(int numberLabel) {
        super();
        this.numberLabel = numberLabel;
        for (int i = 0; i < numberLabel; i++)
            this.add(createLabel(i));
        this.setBorder(new LineBorder(Color.blue));
    }

    @Override
    public void update(Subject subject, int number) {
        if (subject instanceof SynchronizeNumber) {
            SynchronizeNumber synchronizeNumber = (SynchronizeNumber) subject;
            int diff = numberLabel + (number - numberLabel);
            // if diff and numberButton are equal do nothing
            if (diff < numberLabel) {
                for (int i = numberLabel - 1; i >= diff; i--) {
                    this.remove(this.getComponent(i));
                }
            } else if (diff > numberLabel) {
                for (int i = numberLabel; i < diff; i++) {
                    this.add(createLabel(i));
                }
            }
            numberLabel = number;
            System.out.println("LabelPanel, numberLabel: " + numberLabel);
        }
    }

    /**
     * @return the numberLabel
     */
    public int getNumberLabel() {
        return numberLabel;
    }

    /**
     * @param numberLabel
     *            the numberLabel to set
     */
    public void setNumberLabel(int numberLabel) {
        this.numberLabel = numberLabel;
    }

    private JLabel createLabel(int i) {
        return new JLabel("label name:" + ++i);
    }
}

public class Test {

    public static void main(String[] args) {
        JFrame f = new JFrame();
        f.setLayout(new GridLayout(2, 1));

        // create an subject synchronizeNumber
        SynchronizeNumber synchronizeNumber = new SynchronizeNumber();

        // set number to 1
        synchronizeNumber.setNumberSync(1);

        // create observers buttonPanel and labelPanel
        ButtonPanel buttonPanel = new ButtonPanel(synchronizeNumber.getNumberSync());
        LabelPanel labelPanel = new LabelPanel(synchronizeNumber.getNumberSync());

        // add buttonPanel and labelPanel as observers
        synchronizeNumber.addObserver(buttonPanel);
        synchronizeNumber.addObserver(labelPanel);

        // make a change manually
        synchronizeNumber.setNumberSync(4);

        synchronizeNumber.setNumberSync(3);
        synchronizeNumber.setNumberSync(11);
        synchronizeNumber.setNumberSync(5);
        synchronizeNumber.setNumberSync(7);

        f.add(buttonPanel);
        f.add(labelPanel);
        f.setSize(400, 400);
        f.setLocationRelativeTo(null);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setVisible(true);
    }

}

如何在Java Swing中同步两个视图

2 个答案: