我的这个Java程序怎么修改，按钮才有选择图片的功能

import java.awt.*;import java.net.URL;import javax.swing.*;public class lianxi1 extends JFrame{Image img;JButton jbutton;public lianxi1(){ URL imgUrl=URL.class.getResource("/img1.jpg"); img=Toolkit.getDefaultToolkit().getImage(imgUrl); jbutton=new JButton("旋转") ; this.setSize(500,500); this.setTitle("绘图图片"); this.add(new lianxi()); } public static void main(String[] args) { new lianxi1().setVisible(true);}class lianxi extends Canvas{ public void paint(Graphics g){ super.paint(g); Graphics2D g2=(Graphics2D)g; g2.drawImage(img,0,0,this); g2.rotate(60); }}}