java frame 类编写登陆界面！输入用户名：123密码：123。点击登陆按钮则登陆成功！输入其他显示登陆失败！

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.Statement;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JPasswordField;

import javax.swing.JTextField;

import java.awt.Color;

import java.awt.Frame;

import java.awt.Graphics;

import java.awt.event.WindowAdapter;

import java.awt.event.WindowEvent;

public class 登陆界面 extends JFrame {

private static final long serialVersionUID = 1L;

private JPasswordField passwordField;

private JTextField textField;

public static void main(String args[]) {

try {

登陆界面 frame = new 登陆界面();

frame.setVisible(true);

} catch (Exception e) {

e.printStackTrace();

}

}

/**

* Create the frame

*/

public 登陆界面() {

super();

getContentPane().setLayout(null);

setBounds(100, 100, 500, 375);

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

final JButton button = new JButton();

button.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

String dir = "com.mysql.jdbc.Driver";//数据库驱动类，我这是MySQL的 ，连数据库记得导入驱动的jar包

Connection conn = null;

Statement stat = null;

ResultSet rs = null;

try{

Class.forName(dir);

String url = "jdbc:mysql://localhost:3306/hospital?user=root&password=root";//数据库名 hospital用户名和密码都是root

conn = DriverManager.getConnection(url);

stat = conn.createStatement();

//得到用户名

String name = textField.getText().trim();

//得到密码

char[] pass = passwordField .getPassword();

String password = new String(pass);

//输出用户名密码

System.out.println(name);

System.out.println(password);

//数据库表user,字段用户名为username,密码password,都是varchar型

String sql = "select username,password from user where username = "" + name + """;

rs = stat.executeQuery(sql.toString());

if(rs.next()){

//获得数据库里面的用户名和密码

String sname = rs.getString("username");

String spass = rs.getString("password");

//对输入的用户名和密码和数据库里的进行判断

if((rs != null ) && (name.equals(sname)) && (password.equals(spass))) {

//登陆成功释放登陆界面资源，显示a窗口

登陆界面.this.dispose();

new MyFrame1().launch();

System.out.println("chenggong");

} else {

//密码错误，显示b窗口

登陆界面.this.dispose();

new MyFrame2().launch();

System.out.println("mimacuowu");

}

} else {

//用户名错误和其他情况，显示b窗口

登陆界面.this.dispose();

new MyFrame2().launch();

System.out.println("yonghumingcuowu");

}

}catch(Exception e1){

//数据库连接失败，显示b窗口

登陆界面.this.dispose();

new MyFrame2().launch();

System.out.println("数据库连接错误");

}finally{

try{

if(rs!=null) rs.close();

if(stat!=null) stat.close();

if(conn!=null) conn.close();

}catch(Exception e1){

}

}

}

});

button.setText("确定");

button.setBounds(62, 273, 101, 25);

getContentPane().add(button);

final JButton button_1 = new JButton();

button_1.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent arg0) {System.exit(0);

}

});

button_1.setText("取消");

button_1.setBounds(325, 273, 101, 25);

getContentPane().add(button_1);

final JLabel label = new JLabel();

label.setText("用户名");

label.setBounds(23, 60, 60, 15);

getContentPane().add(label);

final JLabel label_1 = new JLabel();

label_1.setText("密码");

label_1.setBounds(23, 172, 60, 15);

getContentPane().add(label_1);

textField = new JTextField();

textField.setBounds(48, 115, 90, 21);

getContentPane().add(textField);

passwordField = new JPasswordField();

passwordField.setBounds(42, 216, 96, 25);

getContentPane().add(passwordField);

}

}

class MyFrame1 extends Frame {

int orgX1;

int orgY1;

int orgX2;

int orgY2;

public void launch() {

setBounds(500,500,500,500);

setVisible(true);

addWindowListener(new WindowAdapter() {

public void windowClosing(WindowEvent e) {

e.getWindow().dispose();

System.exit(0);

}

});

}

public void paint(Graphics g) {

//Color c =g.getColor();

g.setColor(Color.red);

g.drawLine(100, 50, 100, 80);

}

}

class MyFrame2 extends Frame {

int orgX1;

int orgY1;

int orgX2;

int orgY2;

public void launch() {

setBounds(500,500,500,500);

setVisible(true);

addWindowListener(new WindowAdapter() {

public void windowClosing(WindowEvent e) {

e.getWindow().dispose();

System.exit(0);

}

});

}

public void paint(Graphics g) {

//Color c =g.getColor();

g.setColor(Color.red);

g.draw3DRect(100, 100, 100, 100,true);

}

}

import java.awt.BorderLayout;

import java.awt.event.MouseAdapter;

import java.awt.event.MouseEvent;

import javax.swing.JButton;

import javax.swing.JLabel;

import javax.swing.JOptionPane;

import javax.swing.JPanel;

import javax.swing.JPasswordField;

import javax.swing.JTextField;

import javax.swing.WindowConstants;

public class Login extends javax.swing.JFrame {

private JPanel jPanel1;

private JButton bntOk;

private JPasswordField pwd;

private JTextField username;

private JLabel jLabel2;

private JLabel jLabel1;

public static void main(String[] args) {

Login inst = new Login();

inst.setLocationRelativeTo(null);

inst.setVisible(true);

}

public Login() {

super();

initGUI();

}

private void initGUI() {

try {

setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);

{

jPanel1 = new JPanel();

getContentPane().add(jPanel1, BorderLayout.CENTER);

jPanel1.setLayout(null);

{

jLabel1 = new JLabel();

jPanel1.add(jLabel1);

jLabel1.setText("u7528u6237u540duff1a");

jLabel1.setBounds(46, 49, 77, 22);

}

{

jLabel2 = new JLabel();

jPanel1.add(jLabel2);

jLabel2.setText("u5bc6u7801uff1a");

jLabel2.setBounds(46, 95, 53, 15);

}

{

username = new JTextField();

jPanel1.add(username);

username.setBounds(108, 49, 140, 22);

}

{

pwd = new JPasswordField();

jPanel1.add(pwd);

pwd.setBounds(106, 91, 143, 22);

}

{

bntOk = new JButton();

jPanel1.add(bntOk);

bntOk.setText("u767bu5f55");

bntOk.setBounds(52, 143, 66, 30);

bntOk.addMouseListener(new MouseAdapter() {

@Override

public void mouseClicked(MouseEvent e) {

if (username.getText().equals("123")

&& pwd.getText().equals("123")) {

JOptionPane.showMessageDialog(Login.this,

"登录成功");

} else {

JOptionPane.showMessageDialog(Login.this,

"登录失败");

}

}

});

}

}

pack();

setSize(400, 300);

} catch (Exception e) {

e.printStackTrace();

}

}

}

给你写了个例子