如何在JScrollPane放置JPanel

在未加JScrollPane前 带图片的JPanel能显示
为什么把它加在JScrollPane中就不能显示了 谢谢
JScrollPane如何使用
注:用到的图片为 "C:/Pig.JPG"的大约130*130图片


代码1
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;

import javax.swing.*;
import javax.swing.event.*;
import javax.swing.filechooser.FileFilter;
import java.io.*;
import javax.imageio.*;

public class Test extends JFrame
{
public JPanel panel;
public JScrollPane p;

public static void main(String args[])
{
Test demo = new Test();
demo.setTitle("Test ");
demo.setVisible(true);
}

public Test()
{
this.setSize(1000,500);
Container contentPane = getContentPane();

panel = new JPanel();

ImageBox box = new ImageBox("C:/Pig.JPG");
box.addMouseListener(new java.awt.event.MouseAdapter() {
public void mousePressed(java.awt.event.MouseEvent e) {
System.out.println("mousePressed1()");
}
});

panel.add(box);

contentPane.add(panel);
}
}
代码2
class ImageBox extends JLabel
{
private Image img;
public int imageWidth;
public int imageHeight;

public ImageBox(String name)
{
super(new ImageIcon(name));
}
}


import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;

import javax.swing.*;
import javax.swing.event.*;
import javax.swing.filechooser.FileFilter;
import java.io.*;
import javax.imageio.*;

public class Test extends JFrame
{
public JPanel panel;
public JScrollPane p;

public static void main(String args[])
{
Test demo = new Test();
demo.setTitle("Test ");
demo.setVisible(true);
}

public Test()
{
this.setSize(1000,500);
Container contentPane = getContentPane();
p = new JScrollPane();
p.setBounds(300,300,300,300);
contentPane.add(p);

panel = new JPanel();

ImageBox box = new ImageBox("C:/Pig.JPG");
box.addMouseListener(new java.awt.event.MouseAdapter() {
public void mousePressed(java.awt.event.MouseEvent e) {
System.out.println("mousePressed1()");
}
});

panel.add(box);

p.add(panel);
}
}

class ImageBox extends JLabel
{
private Image img;
public int imageWidth;
public int imageHeight;

public ImageBox(String name)
{
super(new ImageIcon(name));
}
}