用Java代码写一个学生成绩管理系统 要求1：带有图形界面。（20%） 要求2：登录时输入用户名密码。（20%） 要求3：能够录入、查询、修改、删除课程。（20%） 要求4：能够录入、查询、修改、删除学生某个课程的成绩。（20%） 要求5：能够持久化。（20%）

好的，以下是一些基本的代码实现思路和步骤，供您参考：

1. 设计数据库表结构，并使用Java连接数据库，实现数据的持久化。可以使用MySQL、Oracle、SQL Server等关系型数据库。示例代码如下：

import java.sql.*;

public class Database {
    private Connection connection;
    private Statement statement;
    private ResultSet resultSet;
    private String url = "jdbc:mysql://localhost:3306/student?useSSL=false&serverTimezone=UTC";
    private String user = "root";
    private String password = "123456";

    public Database() {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            connection = DriverManager.getConnection(url, user, password);
            statement = connection.createStatement();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public ResultSet executeQuery(String sql) {
        try {
            resultSet = statement.executeQuery(sql);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return resultSet;
    }

    public boolean executeUpdate(String sql) {
        try {
            statement.executeUpdate(sql);
            return true;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

    public void close() {
        try {
            if (resultSet != null) {
                resultSet.close();
            }
            if (statement != null) {
                statement.close();
            }
            if (connection != null) {
                connection.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

2. 使用Java GUI框架，如Swing或JavaFX，实现图形界面。示例代码如下：

import javax.swing.*;

public class GUI extends JFrame {
    private JLabel label;
    private JTextField textField;
    private JButton button;

    public GUI() {
        setTitle("学生成绩管理系统");
        setSize(600, 400);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(null);

        label = new JLabel("请输入用户名：");
        label.setBounds(100, 100, 120, 30);
        add(label);

        textField = new JTextField();
        textField.setBounds(220, 100, 120, 30);
        add(textField);

        button = new JButton("登录");
        button.setBounds(350, 100, 80, 30);
        add(button);

        setVisible(true);
    }
}

3. 实现登录功能，可以使用Java中的JPasswordField类实现密码输入框，并使用JDBC连接数据库进行用户验证。示例代码如下：

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

public class LoginGUI extends JFrame {
    private JLabel userLabel;
    private JLabel passwordLabel;
    private JTextField userTextField;
    private JPasswordField passwordField;
    private JButton loginButton;
    private Database database;

    public LoginGUI() {
        setTitle("学生成绩管理系统 - 登录");
        setSize(600, 400);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(null);

        userLabel = new JLabel("用户名：");
        userLabel.setBounds(100, 100, 80, 30);
        add(userLabel);

        userTextField = new JTextField();
        userTextField.setBounds(220, 100, 120, 30);
        add(userTextField);

        passwordLabel = new JLabel("密码：");
        passwordLabel.setBounds(100, 150, 80, 30);
        add(passwordLabel);

        passwordField = new JPasswordField();
        passwordField.setBounds(220, 150, 120, 30);
        add(passwordField);

        loginButton = new JButton("登录");
        loginButton.setBounds(220, 200, 80, 30);
        add(loginButton);

        database = new Database();

        loginButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String username = userTextField.getText();
                String password = new String(passwordField.getPassword());
                ResultSet resultSet = database.executeQuery("select * from user where username='" + username + "' and password='" + password + "'");
                try {
                    if (resultSet.next()) {
                        JOptionPane.showMessageDialog(null, "登录成功！");
                        dispose();
                        new MainGUI();
                    } else {
                        JOptionPane.showMessageDialog(null, "用户名或密码错误！");
                    }
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        });

        setVisible(true);
    }

    public static void main(String[] args) {
        new LoginGUI();
    }
}

4. 实现录入、查询、修改、删除课程的功能。可以通过输入表单，将数据插入到数据库中；通过查询条件，查询数据库中的数据；通过修改表单，修改数据库中的数据；通过删除操作，删除数据库中的数据。示例代码如下：

import javax.swing.*;
import javax.swing.table.DefaultTableModel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.ResultSet;

public class CourseGUI extends JFrame {
    private JLabel nameLabel;
    private JLabel creditLabel;
    private JTextField nameTextField;
    private JTextField creditTextField;
    private JButton addButton;
    private JButton searchButton;
    private JButton updateButton;
    private JButton deleteButton;
    private JTable table;
    private DefaultTableModel tableModel;
    private JScrollPane scrollPane;
    private Database database;

    public CourseGUI() {
        setTitle("学生成绩管理系统 - 课程管理");
        setSize(800, 600);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(null);

        nameLabel = new JLabel("课程名称：");
        nameLabel.setBounds(100, 50, 80, 30);
        add(nameLabel);

        nameTextField = new JTextField();
        nameTextField.setBounds(200, 50, 120, 30);
        add(nameTextField);

        creditLabel = new JLabel("学分：");
        creditLabel.setBounds(350, 50, 80, 30);
        add(creditLabel);

        creditTextField = new JTextField();
        creditTextField.setBounds(450, 50, 80, 30);
        add(creditTextField);

        addButton = new JButton("添加");
        addButton.setBounds(550, 50, 80, 30);
        add(addButton);

        searchButton = new JButton("查询");
        searchButton.setBounds(650, 50, 80, 30);
        add(searchButton);

        updateButton = new JButton("修改");
        updateButton.setBounds(550, 100, 80, 30);
        add(updateButton);

        deleteButton = new JButton("删除");
        deleteButton.setBounds(650, 100, 80, 30);
        add(deleteButton);

        tableModel = new DefaultTableModel();
        tableModel.addColumn("编号");
        tableModel.addColumn("课程名称");
        tableModel.addColumn("学分");
        table = new JTable(tableModel);
        scrollPane = new JScrollPane(table);
        scrollPane.setBounds(100, 150, 600, 300);
        add(scrollPane);

        database = new Database();

        addButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String name = nameTextField.getText();
                String credit = creditTextField.getText();
                database.executeUpdate("insert into course (name, credit) values ('" + name + "', " + credit + ")");
                JOptionPane.showMessageDialog(null, "添加成功！");
            }
        });

        searchButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String name = nameTextField.getText();
                tableModel.setRowCount(0);
                ResultSet resultSet = database.executeQuery("select * from course where name like '%" + name + "%'");
                try {
                    while (resultSet.next()) {
                        Object[] rowData = new Object[3];
                        rowData[0] = resultSet.getInt("id");
                        rowData[1] = resultSet.getString("name");
                        rowData[2] = resultSet.getDouble("credit");
                        tableModel.addRow(rowData);
                    }
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        });

        updateButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                int row = table.getSelectedRow();
                if (row >= 0) {
                    int id = (int) tableModel.getValueAt(row, 0);
                    String name = (String) tableModel.getValueAt(row, 1);
                    double credit = (double) tableModel.getValueAt(row, 2);
                    database.executeUpdate("update course set name='" + name + "', credit=" + credit + " where id=" + id);
                    JOptionPane.showMessageDialog(null, "修改成功！");
                } else {
                    JOptionPane.showMessageDialog(null, "请选择要修改的数据！");
                }
            }
        });

        deleteButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e)