java编写学生管理演示系统的程序初稿，要连接mysql数据库，并且包括学生id、姓名、性别、年龄、电话号码、家庭住址等。代码中要实现学生信息添加、删除、修改等功能。代码中实现在键盘上输入1、2、3等数字，实现学生信息的增加、删除、修改等操作。并将代码整合到一起。

以下是一个初步的Java程序，用于连接MySQL数据库，实现学生信息的添加、删除和修改。

首先需要创建一个名为“Student”的Java类，包含学生ID、姓名、性别、年龄、电话号码和家庭住址等属性：

public class Student {
    private int id;
    private String name;
    private String gender;
    private int age;
    private String phone;
    private String address;

    public Student(int id, String name, String gender, int age, String phone, String address) {
        this.id = id;
        this.name = name;
        this.gender = gender;
        this.age = age;
        this.phone = phone;
        this.address = address;
    }

    // Getters and setters for each attribute
}

接下来需要创建一个名为“StudentManagement”的Java类，用于实现学生信息的增加、删除和修改。该类需要连接MySQL数据库，因此需要使用Java JDBC API。以下是一个基本的示例代码：

import java.sql.*;

public class StudentManagement {
    private Connection conn;

    public StudentManagement() throws SQLException {
        // Connect to the database
        String url = "jdbc:mysql://localhost:3306/students";
        String user = "root";
        String password = "password";
        conn = DriverManager.getConnection(url, user, password);
    }

    public void addStudent(Student student) throws SQLException {
        // Insert a new student into the database
        String sql = "INSERT INTO student (id, name, gender, age, phone, address) VALUES (?, ?, ?, ?, ?, ?)";
        PreparedStatement stmt = conn.prepareStatement(sql);
        stmt.setInt(1, student.getId());
        stmt.setString(2, student.getName());
        stmt.setString(3, student.getGender());
        stmt.setInt(4, student.getAge());
        stmt.setString(5, student.getPhone());
        stmt.setString(6, student.getAddress());
        stmt.executeUpdate();
    }

    public void deleteStudent(int id) throws SQLException {
        // Delete a student from the database
        String sql = "DELETE FROM student WHERE id = ?";
        PreparedStatement stmt = conn.prepareStatement(sql);
        stmt.setInt(1, id);
        stmt.executeUpdate();
    }

    public void updateStudent(Student student) throws SQLException {
        // Update a student in the database
        String sql = "UPDATE student SET name = ?, gender = ?, age = ?, phone = ?, address = ? WHERE id = ?";
        PreparedStatement stmt = conn.prepareStatement(sql);
        stmt.setString(1, student.getName());
        stmt.setString(2, student.getGender());
        stmt.setInt(3, student.getAge());
        stmt.setString(4, student.getPhone());
        stmt.setString(5, student.getAddress());
        stmt.setInt(6, student.getId());
        stmt.executeUpdate();
    }

    public void close() throws SQLException {
        // Close the database connection
        conn.close();
    }
}

最后，需要编写一个主程序，以实现在键盘上输入数字1、2、3等来进行学生信息的增加、删除和修改操作。以下是一个基本的示例代码：

import java.sql.SQLException;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws SQLException {
        StudentManagement sm = new StudentManagement();
        Scanner scanner = new Scanner(System.in);

        while(true) {
            System.out.println("1. Add student");
            System.out.println("2. Delete student");
            System.out.println("3. Update student");
            System.out.println("4. Quit");

            int choice = scanner.nextInt();

            if (choice == 1) {
                System.out.print("Enter student ID: ");
                int id = scanner.nextInt();

                System.out.print("Enter student name: ");
                String name = scanner.next();

                System.out.print("Enter student gender: ");
                String gender = scanner.next();

                System.out.print("Enter student age: ");
                int age = scanner.nextInt();

                System.out.print("Enter student phone number: ");
                String phone = scanner.next();

                System.out.print("Enter student address: ");
                String address = scanner.next();

                Student student = new Student(id, name, gender, age, phone, address);
                sm.addStudent(student);

                System.out.println("Student added successfully!");
            }
            else if (choice == 2) {
                System.out.print("Enter student ID: ");
                int id = scanner.nextInt();

                sm.deleteStudent(id);

                System.out.println("Student deleted successfully!");
            }
            else if (choice == 3) {
                System.out.print("Enter student ID: ");
                int id = scanner.nextInt();

                System.out.print("Enter updated student name: ");
                String name = scanner.next();

                System.out.print("Enter updated student gender: ");
                String gender = scanner.next();

                System.out.print("Enter updated student age: ");
                int age = scanner.nextInt();

                System.out.print("Enter updated student phone number: ");
                String phone = scanner.next();

                System.out.print("Enter updated student address: ");
                String address = scanner.next();

                Student student = new Student(id, name, gender, age, phone, address);
                sm.updateStudent(student);

                System.out.println("Student updated successfully!");
            }
            else if (choice == 4) {
                sm.close();
                break;
            }
            else {
                System.out.println("Invalid choice!");
            }
        }
    }
}

这个程序仅仅是一个初稿，还有很多可以改进的地方。例如，可以添加输入验证和异常处理，以及实现更多的学生管理功能。