<分区>
我有一个程序允许用户使用 Graphics 添加矩形和圆形到 JPanel。我想要做的是将当前 JPanel 的当前状态(即所有形状及其位置)保存到一个文件中，并能够加载该文件并恢复该状态。我有一个 Shapes 类，它扩展 JPanel 并完成所有绘图并使用 ArrayList 跟踪形状。
我可以简单地保存面板的状态吗？还是我必须将形状数据保存到文件中并在“打开”文件时重新绘制形状？
谁能指导我如何保存 JPanel 的当前状态并重新打开它？谢谢
public class UMLEditor {
public static void main(String[] args) {
JFrame frame = new UMLWindow();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setBounds(30, 30, 1000, 700);
frame.getContentPane().setBackground(Color.white);
frame.setVisible(true);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
class UMLWindow extends JFrame {
Shapes shapeList = new Shapes();
public UMLWindow() {
addMenus();
}
public void addMenus() {
getContentPane().add(shapeList);
JMenuBar menubar = new JMenuBar();
JMenu file = new JMenu("File");
JMenuItem openMenuItem = new JMenuItem("Open File");
openMenuItem.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
// Open saved state
});
JMenuItem saveMenuItem = new JMenuItem("Save");
saveMenuItem.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
// Save current state
}
});
file.add(openMenuItem);
file.add(saveMenuItem);
JMenu shapes = new JMenu("Shapes");
file.setMnemonic(KeyEvent.VK_F);
JMenuItem rectangleMenuItem = new JMenuItem("New Rectangle");
rectangleMenuItem.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent event) {
shapeList.addSquare(100, 100);
}
});
JMenuItem circleMenuItem = new JMenuItem("New Circle");
circleMenuItem.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
shapeList.addCircle(100, 100);
}
});
shapes.add(rectangleMenuItem);
shapes.add(circleMenuItem);
menubar.add(file);
menubar.add(shapes);
setJMenuBar(menubar);
setSize(300, 200);
setLocationRelativeTo(null);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
}
// Shapes class, used to draw the shapes on the panel
// as well as implements the MouseListener for dragging
class Shapes extends JPanel {
private static final long serialVersionUID = 1L;
private List<Path2D> shapes = new ArrayList<Path2D>();
int currentIndex;
public Shapes() {
MyMouseAdapter myMouseAdapter = new MyMouseAdapter();
addMouseListener(myMouseAdapter);
addMouseMotionListener(myMouseAdapter);
}
public void addSquare(int width, int height) {
Path2D rect2 = new Path2D.Double();
rect2.append(new Rectangle(getWidth() / 2 - width / 2, getHeight() / 2
- height / 2, width, height), true);
shapes.add(rect2);
repaint();
}
public void addCircle(int width, int height) {
Path2D rect2 = new Path2D.Double();
rect2.append(new Ellipse2D.Double(getWidth() / 2 - width / 2,
getHeight() / 2 - height / 2, width, height), true);
shapes.add(rect2);
repaint();
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
this.setOpaque(true);
this.setBackground(Color.WHITE);
Graphics2D g2 = (Graphics2D) g;
for (Path2D rect : shapes) {
g2.draw(rect);
}
}
class MyMouseAdapter extends MouseAdapter {
private boolean pressed = false;
private Point point;
@Override
public void mousePressed(MouseEvent e) {
if (e.getButton() != MouseEvent.BUTTON1) {
return;
}
for (int i = 0; i < shapes.size(); i++) {
if (shapes.get(i) != null
&& shapes.get(i).contains(e.getPoint())) {
currentIndex = i;
pressed = true;
this.point = e.getPoint();
}
}
}
@Override
public void mouseDragged(MouseEvent e) {
if (pressed) {
int deltaX = e.getX() - point.x;
int deltaY = e.getY() - point.y;
shapes.get(currentIndex).transform(
AffineTransform.getTranslateInstance(deltaX, deltaY));
point = e.getPoint();
repaint();
}
}
@Override
public void mouseReleased(MouseEvent e) {
pressed = false;
}
}
}