程序代码：

import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.Color;
import java.awt.Font;
import java.awt.Label;
import java.awt.Panel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.swing.Box;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
@SuppressWarnings("serial")
public class price extends JFrame implements ActionListener,DocumentListener
{
    Panel p1,p2,p3;
    Box b1,b2,b3,b4;
    Label nom,name,p,count,money;
    JTextField f1,f2,f3,f4,f5;
    Button bt1,bt2,bt3,bt4,bt5;
    String DBDriver = "sun.jdbc.odbc.JdbcOdbcDriver";
    String connectionStr = "jdbc:odbc:shang";
    Connection con = null;
    Statement stmt = null;
    ResultSet rs = null;
    PreparedStatement pstmt = null;
    int search = 0;
    private JPanel kl;
    private ImageIcon i;

    public price()
    {
        super();
        i = new ImageIcon("welcome.jpg");        //背景图片
        JLabel la = new JLabel(i);
        la.setBounds(0,0,i.getIconWidth(),i.getIconHeight());        //把图片填满整个
        kl = (JPanel)this.getContentPane();
        kl.setOpaque(false);        //使窗口透明化
        this.getLayeredPane().setLayout(null);        //把背景图片添加到分层窗口的最低层作为背景
        this.getLayeredPane().add(la,new Integer(Integer.MIN_VALUE));
        this.setSize(i.getIconWidth(),i.getIconHeight());
   
        kl.setLayout(new BorderLayout());
        Label lo = new Label("仓库信息查询");
        kl.add(lo,BorderLayout.NORTH);
        b1 = Box.createVerticalBox();
        b2 = Box.createVerticalBox();
        nom = new Label("编号");
        name = new Label("名称");
        p = new Label("单价");
        count = new Label("数量");
        money = new Label("总价");
        f1 = new JTextField(15);
        f2 = new JTextField(15);
        f3 = new JTextField(15);
        f4 = new JTextField(15);
        f5 = new JTextField(15);
        f1.setFont(new Font("宋体", Font.PLAIN, 14));
        f2.setFont(new Font("宋体", Font.PLAIN, 14));
        f3.setFont(new Font("宋体", Font.PLAIN, 14));
        f4.setFont(new Font("宋体", Font.PLAIN, 14));
        f5.setFont(new Font("宋体", Font.PLAIN, 14));
        f3.getDocument().addDocumentListener(this);
        f4.getDocument().addDocumentListener(this);
   
        b1.add(nom);
        b1.add(Box.createVerticalStrut(20));
        b1.add(name);
        b1.add(Box.createVerticalStrut(20));
        b1.add(p);
        b1.add(Box.createVerticalStrut(20));
        b1.add(count);
        b1.add(Box.createVerticalStrut(20));
        b1.add(money);
        b2.add(f1);
        b2.add(Box.createVerticalStrut(20));
        b2.add(f2);
        b2.add(Box.createVerticalStrut(20));
        b2.add(f3);
        b2.add(Box.createVerticalStrut(20));
        b2.add(f4);
        b2.add(Box.createVerticalStrut(20));
        b2.add(f5);
        b3 = Box.createHorizontalBox();
        b3.add(b1);
        b3.add(Box.createHorizontalStrut(10));
        b3.add(b2);
        p1 = new Panel();
        p3 = new Panel();
        p1.add(b3);
    //    p1.setBackground(Color.LIGHT_GRAY);
    //    p3.setBackground(Color.LIGHT_GRAY);
        bt1 = new Button("添加");
        bt2 = new Button("删除");
        bt3 = new Button("查询");
        bt4 = new Button("重置");
//        bt1.addActionListener(this);
//        bt2.addActionListener(this);
//        bt3.addActionListener(this);
//        bt4.addActionListener(this);
        p3.add(bt1);
        p3.add(bt2);
        p3.add(bt3);
        p3.add(bt4);
        kl.add(p1,BorderLayout.CENTER);
        kl.add(p3,BorderLayout.SOUTH);
   
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        this.setVisible(true);
        this.setLocationRelativeTo(null);
    }
            //以下是无关紧要的access数据表的内容,我就没有复制上来
    public static void main(String shang[])
    {
        new price();
    }

    public void changedUpdate(DocumentEvent e)
    {
        doChange();
    }

    public void insertUpdate(DocumentEvent e)
    {
        doChange();
    }

    public void removeUpdate(DocumentEvent e)
    {
        doChange();
    }
    public void doChange()
    {
        try
        {
            int n1 = Integer.parseInt(f3.getText());
            int n2 = Integer.parseInt(f4.getText());
            f5.setText(String.valueOf(n1*n2));
        } catch (Exception ee)
        {}
    }
}