从文件自定义jcomponents保存和加载java

Question

当我试图保存并从文件加载一个扩展JLabel的对象（并随后添加到JPanel）时，该对象可以通过鼠标拖动来移动，它被放置在第一个setBounds（）设置的位置。我甚至尝试在mouseDragged中调用setBounds（），但它不起作用。有没有比保存最后一个坐标然后在从文件加载时再次调用setBounds（）更聪明的方法？ù 我需要保存的对象与此类似：

编辑：这是否适用于SSCCE

package prove;

import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;


public class AppletProve extends JPanel implements MouseListener, MouseMotionListener{

private JLabel a;
public AppletProve(){
    super();
    setLayout(null);
    Dimension dim=Toolkit.getDefaultToolkit().getScreenSize();
    dim.width=(int) (dim.width*0.66);
    dim.height=(int) (dim.height*0.75);
    setPreferredSize(dim);
    addMouseListener(this);
    addMouseMotionListener(this);
}
public void crea(){

    a=new JLabel("PROVA");
    a.setBounds(40,40, 40, 40);
    add(a);
    File f=new File("prova.dat");
    ObjectOutputStream oos = null;
    try {
        oos=new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream(f)));
        oos.writeObject(a);
    } catch (Exception e) {
        // TODO Auto-generated catch block
        System.out.println("eccezione salvataggio");
    } finally{
        try {
            oos.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}
public void collega(){
    File f=new File("prova.dat");
    a=new JLabel("prova2");
    ObjectInputStream ois = null;
    try {
        ois=new ObjectInputStream(new BufferedInputStream(new FileInputStream(f)));
        a=(JLabel)ois.readObject();

    } catch (Exception e) {
        System.out.println("eccezione caricamento");
        e.printStackTrace();
    } finally{
        try {
            ois.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    add(a);
    this.validate();
}
@Override
public void mouseClicked(MouseEvent arg0) {
    System.out.println("chiamato");
    collega();
    repaint();

}
@Override
public void mouseEntered(MouseEvent arg0) {
    // TODO Auto-generated method stub

}
@Override
public void mouseExited(MouseEvent arg0) {
    // TODO Auto-generated method stub

}
@Override
public void mousePressed(MouseEvent arg0) {
    // TODO Auto-generated method stub

}
@Override
public void mouseReleased(MouseEvent arg0) {
    // TODO Auto-generated method stub

}
@Override
public void mouseDragged(MouseEvent arg0) {
    a.setLocation(arg0.getPoint());
    a.repaint();

}
@Override
public void mouseMoved(MouseEvent arg0) {
    // TODO Auto-generated method stub

}
public static void main(String[] args){
    SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            createAndShowGUI();
        }
    });     
}
private static void createAndShowGUI() {
    JFrame frame=new JFrame("Prova");
    AppletProve ap=new AppletProve();
    ap.setOpaque(true);
    frame.setContentPane(ap);
    frame.pack();
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    ap.crea();
}
}