编写Python图书管理系统代码

编写一个简单的Python图书管理系统涉及到几个主要组件：书籍模型（Book）、数据库操作、用户界面以及可能的一些基本的业务逻辑。以下是一个简化的例子，使用SQLite数据库和命令行接口：

import sqlite3
from typing import List

class Book:
    def __init__(self, title: str, author: str):
        self.title = title
        self.author = author

    def __str__(self):
        return f"{self.title} by {self.author}"

class Library:
    def __init__(self):
        self.conn = sqlite3.connect('library.db')
        self.cursor = self.conn.cursor()
        self.cursor.execute('''CREATE TABLE IF NOT EXISTS books
                            (id INTEGER PRIMARY KEY AUTOINCREMENT,
                             title TEXT NOT NULL,
                             author TEXT NOT NULL)''')

    def add_book(self, title: str, author: str):
        self.cursor.execute("INSERT INTO books (title, author) VALUES (?, ?)", (title, author))
        self.conn.commit()

    def list_books(self) -> List[Book]:
        self.cursor.execute("SELECT * FROM books")
        rows = self.cursor.fetchall()
        return [Book(*row) for row in rows]

    def remove_book(self, title: str):
        self.cursor.execute("DELETE FROM books WHERE title=?", (title,))
        self.conn.commit()

# 假设我们有一个命令行界面
def main():
    library = Library()
    
    while True:
        print("\nOptions:")
        print("1. Add a book")
        print("2. List books")
        print("3. Remove a book")
        print("4. Exit")
        choice = input("Enter your choice: ")

        if choice == '1':
            title = input("Title: ")
            author = input("Author: ")
            library.add_book(title, author)
        elif choice == '2':
            for book in library.list_books():
                print(book)
        elif choice == '3':
            title = input("Title of the book to remove: ")
            library.remove_book(title)
        elif choice == '4':
            break
        else:
            print("Invalid choice. Try again.")

if __name__ == "__main__":
    main()

在这个例子中，`Library`类负责管理数据库中的书籍信息，包括添加新书、列出所有书和删除指定的书。用户可以通过命令行选择相应的选项进行操作。