Question

如何编写一个登录界面的程序，用户名为admin，密码为123456，如果为空提示请填入用户名和密码，否则登录成

Answer 1

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.sql.*;

public class systems extends JFrame implements ActionListener
{
static systems ss;
JPanel panel = new JPanel();
JLabel label1 = new JLabel("输入姓名：");
JTextField name = new JTextField();
JLabel label2 = new JLabel("密 码：");
JPasswordField pwd = new JPasswordField();
JButton Enter = new JButton("登录");
JButton Exit = new JButton("退出");
String url = "D:\\Systems\\title.jpg";
ButtonGroup bgp = new ButtonGroup();
JRadioButton stu = new JRadioButton("普通用户");
JRadioButton tch = new JRadioButton("管理员");

public systems()
{
super("登录系统");
this.setResizable(false);
JLabel img = new JLabel(new ImageIcon(url));
img.setBounds(0,0,500,100);
panel.add(img);
stu.setBounds(165,210,70,20);
tch.setBounds(265,210,70,20);
bgp.add(stu);
bgp.add(tch);
panel.add(stu);
panel.add(tch);
Enter.setBounds(150,250,80,20);
Exit.setBounds(270,250,80,20);
Enter.addActionListener(this);
Exit.addActionListener(this);
panel.add(Enter);
panel.add(Exit);
panel.setLayout(null);
this.add(panel);
label1.setBounds(135,130,100,25);
panel.add(label1);
name.setBounds(265,130,100,25);
panel.add(name);
label2.setBounds(135,165,100,25);
panel.add(label2);
pwd.setBounds(265,165,100,25);
panel.add(pwd);
this.setBounds(100,100,500,350);
this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

public void actionPerformed(ActionEvent e)
{
if(e.getSource()==Enter)
{
String username , password;
username = name.getText();
password = pwd.getText();
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
}
catch (ClassNotFoundException ce)
{
JOptionPane.showMessageDialog(ss,ce.getMessage());
}
if(stu.isSelected())
{
try
{
Connection con = DriverManager.getConnection("jdbc:odbc:sysdb","sa","");
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("select * from STU");
while(rs.next())
{
if((rs.getString("ID").equals(username))&&(rs.getString("Pwd").equals(password)))
{
JOptionPane.showMessageDialog(ss,"登陆成功");
Students stu = new Students();
}
else
{
JOptionPane.showMessageDialog(ss,"登录失败");
}
}
rs.close();
stmt.close();
}
catch (SQLException se)
{
JOptionPane.showMessageDialog(ss,se.getMessage());
}
}
else if(tch.isSelected())
{
try
{
Connection con = DriverManager.getConnection("jdbc:odbc:systchdb","sa","");
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("select * from TCH");
while(rs.next())
{
if((rs.getString("ID").equals(username))&&(rs.getString("Pwd").equals(password)))
{
JOptionPane.showMessageDialog(ss,"登陆成功");
}
else
{
JOptionPane.showMessageDialog(ss,"登录失败");
}
}
}
catch (SQLException se)
{
JOptionPane.showMessageDialog(ss,se.getMessage());
}
}
}
else
{
System.exit(0);
}
}
注：这是用Java编的，不知道是不是你想要的

public static void main(String[] args)
{
systems sys = new systems();
}
}