程序代码：

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class Login {
    private JFrame jf;
    private Container con;
    private JPanel userJPanel, passJPanel, regJPanel;
    private JLabel userJLabel, passJLabel;
   

    private JTextField userJtf;
    private JPasswordField passJtf;
    private JButton login;
   

    public void init() {
        jf = new JFrame("登录");
        con = jf.getContentPane();
        con.setLayout(new GridLayout(5, 1));
       

        userJLabel = new JLabel("用户名：");
        userJtf = new JTextField(10);
        userJPanel = new JPanel();
        userJPanel.add(userJLabel);
        userJPanel.add(userJtf);
       

        passJLabel = new JLabel("密 码：");
        passJtf = new JPasswordField(10);
        passJPanel = new JPanel();
        passJPanel.add(passJLabel);
        passJPanel.add(passJtf);
       

   

   

        login = new JButton("登陆");
        login.addActionListener(new ActionListener(){
                public void actionPerformed(ActionEvent e) {
                    String userName = userJtf.getText();
                    String pwd = new String(passJtf.getPassword());
                    User user = new User();
                    user.setUserName(userName);
                    user.setPwd(pwd);
                    LoginService service = new LoginService();
                    boolean b = service.login(user);
                    if(b) {
                        JOptionPane.showMessageDialog(jf, "登录成功");
                       

                    } else {
                        JOptionPane.showMessageDialog(jf, "登录失败");
                    }
                }
            });
        regJPanel = new JPanel();
       

        regJPanel.add(login);
       

        con.add(userJPanel);
        con.add(passJPanel);
       

        con.add(regJPanel);
       

        jf.setSize(300, 300);
        jf.setVisible(true);
    }
    public static void main(String[] args) {
        Login login = new Login();
        login.init();

    }
   

}

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class Register {
    private JFrame jf;
    private Container con;
    private JPanel userJPanel, passJPanel, spassJPanel, regJPanel, msgJPanel;
    private JLabel userJLabel, passJLabel, spassJLabel;
    private JLabel msg;
    private JTextField userJtf;
    private JPasswordField passJtf, spassJtf;
    private JButton reset, register;
   

    public void init() {
        jf = new JFrame("注册");
        con = jf.getContentPane();
        con.setLayout(new GridLayout(5, 1));
       

        userJLabel = new JLabel("用户名：");
        userJtf = new JTextField(10);
        userJPanel = new JPanel();
        userJPanel.add(userJLabel);
        userJPanel.add(userJtf);
       

        passJLabel = new JLabel("密 码：");
        passJtf = new JPasswordField(10);
        passJPanel = new JPanel();
        passJPanel.add(passJLabel);
        passJPanel.add(passJtf);
       

        spassJLabel = new JLabel("确认密码：");
        spassJtf = new JPasswordField(10);
        spassJPanel = new JPanel();
        spassJPanel.add(spassJLabel);
        spassJPanel.add(spassJtf);
       

        msg = new JLabel();
        msgJPanel = new JPanel();
        msgJPanel.add(msg);
       

        reset = new JButton("清空");
        reset.addActionListener(new ActionListener(){
                public void actionPerformed(ActionEvent e){
                        userJtf.setText("");
                        passJtf.setText("");
                        spassJtf.setText("");
                    }
            });
        register = new JButton("注册");
        register.addActionListener(new ActionListener(){
                public void actionPerformed(ActionEvent e){
                    String pass = new String(passJtf.getPassword());
                    String spass= new String(spassJtf.getPassword());
                    if(!pass.equals(spass)) {
                        msg.setText("两次密码输入不一致");
                        return ;
                    }

                   

                    String userName = userJtf.getText();
                    User user = new User();
                    user.setUserName(userName);
                    user.setPwd(pass);
                    RegisterService service = new RegisterService();
                    service.register(user);
                    msg.setText("注册成功");
                }
            });
        regJPanel = new JPanel();
        regJPanel.add(reset);
        regJPanel.add(register);
       

        con.add(userJPanel);
        con.add(passJPanel);
        con.add(spassJPanel);
        con.add(msgJPanel);
        con.add(regJPanel);
       

        jf.setSize(300, 300);
        jf.setVisible(true);
    }
    public static void main(String[] args) {
        Register ref = new Register();
        ref.init();

    }
   

}







import *;
public class RegisterService{
    private static final String FILE_PATH = "c:\\user.txt";
    public void register(User user) {
        //获取到用户名和密码
        //存储到文件当中
        String msg = user.getUserName() + "," + user.getPwd();
        BufferedWriter bw = null;
        try {
            bw = new BufferedWriter(new FileWriter(FILE_PATH));
            bw.write(msg);
            bw.flush();
        }
        catch (IOException ex) {
            ex.printStackTrace();
        } finally  {
            try{
                if(bw != null)
                    bw.close();   

            }catch(IOException e) {
                e.printStackTrace();
            }
           

        }
       

    }
}



public class User {
    private String userName;
    private String pwd;
   

    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getUserName() {
        return this.userName;
    }
    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
    public String getPwd() {
        return this.pwd;
    }
}



import *;
public class LoginService {
    private static final String FILE_PATH = "c:\\user.txt";
    public boolean login(User user) {
        //获取文件当中存储的用户名和密码
        //与参数（前台）传递来的用户名和密码进行匹配
        try {
            BufferedReader br = new BufferedReader(new FileReader(FILE_PATH));
            String msg = br.readLine();
            br.close();
            if(msg == null) {
                return false;
            }
            String[] temp = msg.split(",");
            return temp[0].equals(user.getUserName()) && temp[1].equals(user.getPwd());
        }
        catch (Exception ex) {
            return false;
        }
       

    }
}