界面展示

具体代码

//DBUtil.java
package org.example;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DBUtil {
    public static Connection getConnection() throws ClassNotFoundException, SQLException {
        Class.forName("com.mysql.cj.jdbc.Driver");

        Connection connection= DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","20214063");

        return connection;
    }
}

//LoginForm.java
package org.example;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.SQLException;

public class LoginForm extends JFrame {
    //定义系统的各个组件
    private static final long serialVersionUID = 5475179439752076273L;
    private Container container = getContentPane();
    private JLabel userLabel = new JLabel("用 户:");
    private JTextField usernameField = new JTextField();
    private JLabel passLabel = new JLabel("密 码:");
    private JPasswordField passwordField = new JPasswordField();
    private JButton okBtn = new JButton("确定");
    private JButton cancelBtn = new JButton("清空");
    public void init(){
        setTitle("系统登录功能");
        setBounds(600,200,350,180);
        container.setLayout(new BorderLayout());
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //设置让窗口可见
        setVisible(true);

        JPanel fieldPanel = new JPanel();
        fieldPanel.setLayout(null);
        userLabel.setBounds(50, 20, 50, 20);
        passLabel.setBounds(50, 60, 50, 20);
        fieldPanel.add(userLabel);
        fieldPanel.add(passLabel);
        usernameField.setBounds(110, 20, 160, 20);
        passwordField.setBounds(110, 60, 160, 20);
        fieldPanel.add(usernameField);
        fieldPanel.add(passwordField);
        container.add(fieldPanel, "Center");

        //按钮组件部分
        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new FlowLayout());
        buttonPanel.add(okBtn);
        buttonPanel.add(cancelBtn);
        container.add(buttonPanel, "South");
        listerner();
    }

    //登录功能的实现
    public void listerner() {
        okBtn.addActionListener(
                new ActionListener() {
                    @Override
                    public void actionPerformed(ActionEvent e) {
                        try {
                            String username = usernameField.getText();
                            String password = String.valueOf(passwordField.getPassword());
                            //判断是否在数据库中存在这样一条信息
                            UserDAO dao=new UserDAO();
                            boolean a=dao.findUser(username.toString(),password);

                            if(a){
                                JOptionPane.showMessageDialog(null, "登录成功");
                            }else{
                                JOptionPane.showMessageDialog(null, "登录失败");
                            }
                        } catch (ClassNotFoundException | SQLException ex) {
                            throw new RuntimeException(ex);
                        }
                    }
                });

        //清空输入信息
        cancelBtn.addActionListener(
                new ActionListener() {
                    @Override
                    public void actionPerformed(ActionEvent e) {
                        usernameField.setText("");
                        passwordField.setText("");
                    }
                });
    }
}

//UserDAO.java
package org.example;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class UserDAO {
    public boolean findUser(String userName,String password) throws SQLException, ClassNotFoundException {
        Connection connection=DBUtil.getConnection();
        PreparedStatement psmt=connection.prepareStatement("select * from design where id=?");
        psmt.setString(1,userName);
        ResultSet rs=psmt.executeQuery();
        String pa="";
        int count=0;
        while(rs.next()){
            pa=rs.getString(2);
            if(pa.equals(password)){
                count=1;
            }else{
                count=0;
            }
        }

        rs.close();
        psmt.close();
        connection.close();

        if(count!=0){
            return true;
        }else{
            return false;
        }
    }
}

//Main.java
package org.example;

public class Main {
    public static void main(String[] args) {
        LoginForm loginForm=new LoginForm();
        loginForm.init();
    }
}