帮我写一个jdbc的学生管理系统，需要包含学生登录、注册、根据姓名模糊查询，修改学生信息，根据学号删除学生信息。只需要在控制台显示，字段有学号、用户名、真实名、密码、年龄、性别

好的，下面是一个简单的 JDBC 学生管理系统的代码，仅供参考：

import java.sql.*;

public class StudentManager {

    // 数据库连接信息
    private static final String DB_URL = "jdbc:mysql://localhost:3306/student_db";
    private static final String DB_USER = "root";
    private static final String DB_PASSWORD = "password";

    // 数据库表中的字段
    private static final String ID = "id";
    private static final String USERNAME = "username";
    private static final String REALNAME = "realname";
    private static final String PASSWORD = "password";
    private static final String AGE = "age";
    private static final String GENDER = "gender";

    // 创建数据库连接
    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(DB_URL, DB_USER, DB_PASSWORD);
    }

    // 学生登录
    public static boolean login(String username, String password) {
        try (Connection conn = getConnection();
             PreparedStatement stmt = conn.prepareStatement("SELECT * FROM students WHERE username=? AND password=?")) {
            stmt.setString(1, username);
            stmt.setString(2, password);
            try (ResultSet rs = stmt.executeQuery()) {
                return rs.next();
            }
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
    }

    // 学生注册
    public static boolean register(String username, String realname, String password, int age, String gender) {
        try (Connection conn = getConnection();
             PreparedStatement stmt = conn.prepareStatement("INSERT INTO students (username, realname, password, age, gender) VALUES (?, ?, ?, ?, ?)")) {
            stmt.setString(1, username);
            stmt.setString(2, realname);
            stmt.setString(3, password);
            stmt.setInt(4, age);
            stmt.setString(5, gender);
            return stmt.executeUpdate() == 1;
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
    }

    // 根据姓名模糊查询
    public static void searchByName(String name) {
        try (Connection conn = getConnection();
             PreparedStatement stmt = conn.prepareStatement("SELECT * FROM students WHERE realname LIKE ?")) {
            stmt.setString(1, "%" + name + "%");
            try (ResultSet rs = stmt.executeQuery()) {
                while (rs.next()) {
                    System.out.printf("ID: %s, Username: %s, Realname: %s, Password: %s, Age: %d, Gender: %s\n",
                            rs.getString(ID), rs.getString(USERNAME), rs.getString(REALNAME),
                            rs.getString(PASSWORD), rs.getInt(AGE), rs.getString(GENDER));
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    // 修改学生信息
    public static boolean update(String id, String username, String realname, String password, int age, String gender) {
        try (Connection conn = getConnection();
             PreparedStatement stmt = conn.prepareStatement("UPDATE students SET username=?, realname=?, password=?, age=?, gender=? WHERE id=?")) {
            stmt.setString(1, username);
            stmt.setString(2, realname);
            stmt.setString(3, password);
            stmt.setInt(4, age);
            stmt.setString(5, gender);
            stmt.setString(6, id);
            return stmt.executeUpdate() == 1;
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
    }

    // 根据学号删除学生信息
    public static boolean delete(String id) {
        try (Connection conn = getConnection();
             PreparedStatement stmt = conn.prepareStatement("DELETE FROM students WHERE id=?")) {
            stmt.setString(1, id);
            return stmt.executeUpdate() == 1;
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
    }

    public static void main(String[] args) {
        // 测试代码
        System.out.println(login("user1", "password1")); // true
        System.out.println(login("user1", "wrong_password")); // false

        System.out.println(register("user3", "张三", "password3", 20, "男")); // true

        searchByName("张");

        System.out.println(update("1", "user1_updated", "李四", "password1_updated", 25, "女")); // true

        System.out.println(delete("2")); // true
    }
}

注意：以上代码仅供参考，实际使用中需要根据具体情况进行修改和优化。同时，为了保证安全性，建议使用加密算法对密码进行加密存储。