Experiment 5 components and event handling

One 、 The experiment purpose

         Learn to use component classes ; Learn to use layout classes ; Study Java Event processing mode and processing of various events .

Two 、 Experimental content

         The implementation of the login window is shown in the figure below , Fill in the registration information in the registration window , Click the register button , Will switch to the login window , Enter the user name and password in the login window , If the user name and password are consistent with those entered during registration, the login success dialog box will pop up , Otherwise, the login failure dialog box will pop up .

        reflection ： Modify the program , Save the registration information to a file , Login time , If the user name and password entered are consistent with those saved, the login success dialog box will pop up , Otherwise, the login failure dialog box will pop up .

3、 ... and 、 Code implementation

// Login screen 
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;

public class LoginFrame extends JFrame {
    public LoginFrame() {
        init();
    }

    public void init() {
        JFrame frame = new JFrame(" Login window ");
        frame.setBounds(400, 100, 480, 410);
        frame.setLayout(null);
        Font font = new Font("Serief", Font.BOLD, 18);

        Label lb_username = new Label(" user name ：");
        lb_username.setBounds(100, 76, 76, 20);
        lb_username.setFont(font);
        JTextField jtf_username = new JTextField();
        jtf_username.setBounds(199, 73, 127, 30);
        jtf_username.setFont(font);
        frame.add(lb_username);
        frame.add(jtf_username);

        Label lb_password = new Label(" password ：");
        lb_password.setBounds(100, 143, 76, 20);
        lb_password.setFont(font);
        JPasswordField jpf_password = new JPasswordField();
        jpf_password.setBounds(199, 140, 127, 30);
        jpf_password.setFont(font);
        frame.add(lb_password);
        frame.add(jpf_password);

        JButton btn_login = new JButton("login");
        btn_login.setBounds(190, 220, 80, 40);
        btn_login.setFont(font);
        btn_login.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String username = jtf_username.getText().trim();
                String password = String.valueOf(jpf_password.getPassword());
                File file = new File("./user.txt");
                boolean result = false;
                if (file.exists()) {
                    try {
                        BufferedReader bfr = new BufferedReader(new FileReader(file));
                        String curLine = null;
                        while ((curLine = bfr.readLine()) != null) {
                            System.out.println(curLine);
                            String[] infos = curLine.split("---");
                            if (username.equals(infos[0]) && password.equals(infos[1])) {
                                result = true;
                                break;
                            }
                        }
                        bfr.close();
                        if (result) {
                            frame.setVisible(false);
                            JOptionPane.showMessageDialog(null, " Login successful ！", " Login successful ", JOptionPane.INFORMATION_MESSAGE);
                        } else {
                            JOptionPane.showMessageDialog(null, " Login failed ！", " Login failed ", JOptionPane.ERROR_MESSAGE);
                        }
                    } catch (Exception ep) {
                        ep.printStackTrace();
                    }
                } else {
                    JOptionPane.showMessageDialog(null, " Login failed ！", " Login failed ", JOptionPane.ERROR_MESSAGE);
                }
            }
        });
        frame.add(btn_login);

        frame.setVisible(true);
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    }
}

// The registration screen 
import javafx.scene.control.ComboBox;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileWriter;

public class RegisterFrame {
    public RegisterFrame() {
        init();
    }

    public void init() {
        JFrame frame = new JFrame(" Registration window ");
        frame.setLayout(new FlowLayout(FlowLayout.LEFT, 50, 30));
        frame.setBounds(400, 100, 760, 600);

        Font font = new Font("Serief", Font.BOLD, 18);

        JPanel row1 = new JPanel(new FlowLayout(FlowLayout.LEFT, 20, 5));
        Label lb_username = new Label(" user name ：");
        lb_username.setSize(76, 20);
        lb_username.setFont(font);
        row1.add(lb_username);

        JTextField jtf_username = new JTextField();
        jtf_username.setPreferredSize(new Dimension(140, 30));
        jtf_username.setFont(font);
        row1.add(jtf_username);

        Label lb_password = new Label(" password ：");
        lb_password.setSize(66, 20);
        lb_password.setFont(font);
        row1.add(lb_password);

        JPasswordField jpf_password = new JPasswordField();
        jpf_password.setPreferredSize(new Dimension(140, 30));
        jpf_password.setFont(font);
        row1.add(jpf_password);

        JPanel row2 = new JPanel(new FlowLayout(FlowLayout.LEFT, 20, 5));

        Label lb_sex = new Label(" Gender ：");
        lb_sex.setSize(66, 20);
        lb_sex.setFont(font);
        row2.add(lb_sex);

        ButtonGroup rbtgp = new ButtonGroup();
        JRadioButton rb1 = new JRadioButton(" male ");
        rb1.setFont(font);
        rb1.setSelected(true);
        JRadioButton rb2 = new JRadioButton(" Woman ");
        rb2.setFont(font);
        rbtgp.add(rb1);
        rbtgp.add(rb2);

        row2.add(rb1);
        row2.add(rb2);

        Label lb_hobby = new Label(" hobby ：");
        lb_hobby.setSize(66, 20);
        lb_hobby.setFont(font);
        row2.add(lb_hobby);
        JCheckBox cb1 = new JCheckBox(" music ");
        cb1.setFont(font);
        JCheckBox cb2 = new JCheckBox(" Domestic tourism ");
        cb2.setFont(font);
        JCheckBox cb3 = new JCheckBox(" read ");
        cb3.setFont(font);

        row2.add(cb1);
        row2.add(cb2);
        row2.add(cb3);

        JPanel row3 = new JPanel(new FlowLayout(FlowLayout.LEFT, 20, 5));
        Label lb_job = new Label(" occupation ：");
        lb_job.setSize(66, 20);
        lb_job.setFont(font);
        row3.add(lb_job);

        JComboBox<String> cb_job = new JComboBox<>();
        cb_job.setFont(font);
        cb_job.setEnabled(true);
        cb_job.addItem(" Student ");
        cb_job.addItem(" Enterprise employees ");
        cb_job.addItem(" Teachers' ");
        row3.add(cb_job);

        Label lb_note = new Label("Note：");
        lb_note.setSize(66, 20);
        lb_note.setFont(font);
        row3.add(lb_note);

        JTextArea ta_note = new JTextArea(10,10);
        ta_note.setFont(font);
        row3.add(ta_note);

        JButton btn_register = new JButton("register");
        btn_register.setFont(font);
        btn_register.setPreferredSize(new Dimension(130, 35));
        btn_register.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String username = jtf_username.getText().trim();
                String password = String.valueOf(jpf_password.getPassword()).trim();
                if (username.equals("") || password.equals("")) {
                    JOptionPane.showMessageDialog(null, " User name or password cannot be empty ！", " Registration failed ", JOptionPane.WARNING_MESSAGE);
                    return;
                }
                try {
                    File file = new File("./user.txt");
                    //  create a file 
                    file.createNewFile();
                    // Write user information to file 
                    FileWriter fw = new FileWriter(file, true);
                    String content = username + "---" + password + "\n";
                    fw.write(content);
                    fw.close();

                    //  Jump to the login screen 
                    frame.setVisible(false);
                    new LoginFrame();
                } catch (Exception ep) {
                    ep.printStackTrace();
                }
            }
        });
        row3.add(btn_register);

        frame.add(row1);
        frame.add(row2);
        frame.add(row3);

        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setVisible(true);

    }
}

// The main program 
public class Test5 {
    public static void main(String[] args) {
        new RegisterFrame();
    }
}

Four 、 Running results