java代码实现一个功能简单的学生信息管理系统，该系统具有按照账户名密码登陆功能，登陆后，可以添加，删除，修改、查询（显示学生相片）学生信息，添加学生信息时，要求能添加学生的相片信息（实现相片文件的上传和下载功能）。

好的，以下是一个简单的Java代码实现学生信息管理系统的示例：

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.sql.*;
import javax.swing.*;

public class StudentInfoManagementSystem extends JFrame implements ActionListener {
    // 登录界面的组件
    private JFrame loginFrame;
    private JTextField usernameField;
    private JPasswordField passwordField;
    private JButton loginButton;

    // 学生信息管理界面的组件
    private JFrame mainFrame;
    private JTable studentTable;
    private JButton addButton;
    private JButton deleteButton;
    private JButton modifyButton;
    private JButton searchButton;

    // 数据库连接
    private Connection conn;

    public StudentInfoManagementSystem() {
        // 初始化登录界面
        loginFrame = new JFrame("登录");
        loginFrame.setSize(300, 200);
        loginFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        loginFrame.setLayout(new GridLayout(3, 2));
        loginFrame.add(new JLabel("账户名:"));
        usernameField = new JTextField();
        loginFrame.add(usernameField);
        loginFrame.add(new JLabel("密码:"));
        passwordField = new JPasswordField();
        loginFrame.add(passwordField);
        loginButton = new JButton("登录");
        loginButton.addActionListener(this);
        loginFrame.add(loginButton);
        loginFrame.setVisible(true);

        // 连接数据库
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/student_info", "root", "password");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    // 登录按钮的事件处理
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == loginButton) {
            String username = usernameField.getText();
            String password = new String(passwordField.getPassword());
            if (checkLogin(username, password)) {
                loginFrame.setVisible(false);
                initMainFrame();
            } else {
                JOptionPane.showMessageDialog(loginFrame, "账户名或密码错误，请重新输入！");
            }
        }
    }

    // 验证登录信息
    private boolean checkLogin(String username, String password) {
        boolean success = false;
        try {
            PreparedStatement stmt = conn.prepareStatement("SELECT * FROM user WHERE username=? AND password=?");
            stmt.setString(1, username);
            stmt.setString(2, password);
            ResultSet rs = stmt.executeQuery();
            if (rs.next()) {
                success = true;
            }
            rs.close();
            stmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return success;
    }

    // 初始化学生信息管理界面
    private void initMainFrame() {
        mainFrame = new JFrame("学生信息管理");
        mainFrame.setSize(800, 600);
        mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        mainFrame.setLayout(new BorderLayout());

        // 显示学生信息的表格
        String[] columnNames = {"学号", "姓名", "年龄", "性别", "照片"};
        Object[][] rowData = getStudentData();
        studentTable = new JTable(rowData, columnNames);
        JScrollPane scrollPane = new JScrollPane(studentTable);
        mainFrame.add(scrollPane, BorderLayout.CENTER);

        // 按钮
        addButton = new JButton("添加");
        addButton.addActionListener(this);
        deleteButton = new JButton("删除");
        deleteButton.addActionListener(this);
        modifyButton = new JButton("修改");
        modifyButton.addActionListener(this);
        searchButton = new JButton("查询");
        searchButton.addActionListener(this);
        JPanel buttonPanel = new JPanel();
        buttonPanel.add(addButton);
        buttonPanel.add(deleteButton);
        buttonPanel.add(modifyButton);
        buttonPanel.add(searchButton);
        mainFrame.add(buttonPanel, BorderLayout.SOUTH);

        mainFrame.setVisible(true);
    }

    // 获取学生信息数据
    private Object[][] getStudentData() {
        Object[][] rowData = null;
        try {
            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery("SELECT * FROM student");
            rs.last();
            int rowCount = rs.getRow();
            rowData = new Object[rowCount][5];
            rs.beforeFirst();
            int i = 0;
            while (rs.next()) {
                rowData[i][0] = rs.getString("id");
                rowData[i][1] = rs.getString("name");
                rowData[i][2] = rs.getInt("age");
                rowData[i][3] = rs.getString("gender");
                rowData[i][4] = new ImageIcon(rs.getString("photo"));
                i++;
            }
            rs.close();
            stmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rowData;
    }

    // 添加学生信息
    private void addStudent() {
        // 弹出对话框，输入学生信息
        JTextField idField = new JTextField();
        JTextField nameField = new JTextField();
        JTextField ageField = new JTextField();
        JTextField genderField = new JTextField();
        JButton photoButton = new JButton("上传照片");
        JFileChooser fileChooser = new JFileChooser();
        photoButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                int returnVal = fileChooser.showOpenDialog(mainFrame);
                if (returnVal == JFileChooser.APPROVE_OPTION) {
                    File file = fileChooser.getSelectedFile();
                    // 将照片保存到本地
                    try {
                        InputStream is = new FileInputStream(file);
                        OutputStream os = new FileOutputStream("photo/" + file.getName());
                        byte[] buffer = new byte[1024];
                        int length;
                        while ((length = is.read(buffer)) > 0) {
                            os.write(buffer, 0, length);
                        }
                        is.close();
                        os.close();
                    } catch (IOException ex) {
                        ex.printStackTrace();
                    }
                }
            }
        });
        JPanel panel = new JPanel(new GridLayout(0, 1));
        panel.add(new JLabel("学号:"));
        panel.add(idField);
        panel.add(new JLabel("姓名:"));
        panel.add(nameField);
        panel.add(new JLabel("年龄:"));
        panel.add(ageField);
        panel.add(new JLabel("性别:"));
        panel.add(genderField);
        panel.add(new JLabel("照片:"));
        panel.add(photoButton);
        int result = JOptionPane.showConfirmDialog(mainFrame, panel, "添加学生信息", JOptionPane.OK_CANCEL_OPTION);
        if (result == JOptionPane.OK_OPTION) {
            // 将学生信息插入到数据库中
            try {
                PreparedStatement stmt = conn.prepareStatement("INSERT INTO student VALUES (?, ?, ?, ?, ?)");
                stmt.setString(1, idField.getText());
                stmt.setString(2, nameField.getText());
                stmt.setInt(3, Integer.parseInt(ageField.getText()));
                stmt.setString(4, genderField.getText());
                stmt.setString(5, "photo/" + fileChooser.getSelectedFile().getName());
                stmt.executeUpdate();
                stmt.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            // 更新学生信息表格
            Object[][] rowData = getStudentData();
            DefaultTableModel model = new DefaultTableModel(rowData, new String[]{"学号", "姓名", "年龄", "性别", "照片"});
            studentTable.setModel(model);
        }
    }

    // 删除学生信息
    private void deleteStudent() {
        int selectedRow = studentTable.getSelectedRow();
        if (selectedRow != -1) {
            String id = studentTable.getValueAt(selectedRow, 0).toString();
            // 从数据库中删除学生信息
            try {
                PreparedStatement stmt = conn.prepareStatement("DELETE FROM student WHERE id=?");
                stmt.setString(1, id);
                stmt.executeUpdate();
                stmt.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            // 更新学生信息表格
            Object[][] rowData = getStudentData();
            DefaultTableModel model = new DefaultTableModel(rowData, new String[]{"学号", "姓名", "年龄", "性别", "照片"});
            studentTable.setModel(model);
        } else {
            JOptionPane.showMessageDialog(mainFrame, "请先选择一行记录！");
        }
    }

    // 修改学生信息
    private void modifyStudent() {
        int selectedRow = studentTable.getSelectedRow();
        if (selectedRow != -1) {
            String id = studentTable.getValueAt(selectedRow, 0).toString();
            // 弹出对话框，输入修改后的学生信息
            JTextField nameField = new JTextField(studentTable.getValueAt(selectedRow, 1).toString());
            JTextField ageField = new JTextField(studentTable.getValueAt(selectedRow, 2).toString());
            JTextField gender