public class Mainwindow extends JFrame {
public Mainwindow() {
super ("图书管理系统");
setSize(500,500);
setBackground(Color.white);
setVisible(true);
pack();
Container con = getContentPane();
JPanel panel = new JPanel();
JButton button1 = new JButton("借出");
JButton button2 = new JButton("归还");
JButton button3 = new JButton("关于");
JLabel label = new JLabel(new ImageIcon("booksystem/mm.jpg"));
//create Query menu
JMenu query = new JMenu("书籍查询");
//create Login menu
JMenu login = new JMenu("用户登陆");
//create System management menu
JMenu management = new JMenu("系统管理");
//create Students' function menu
JMenu stuFunction = new JMenu("学生功能");
//create Help function menu
JMenu help = new JMenu("帮助");
//create menubar
JMenuBar menubar = new JMenuBar();
//set menu to the menubar
menubar.add(query);
menubar.add(login);
menubar.add(management);
menubar.add(stuFunction);
menubar.add(help);