写一个图书管理系统的代码

好的，这里给你一个简单的图书管理系统的代码，使用 Python 语言编写，主要功能包括添加图书、借阅图书、归还图书和查询图书：

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

class Library:
    def __init__(self):
        self.books = []

    # 添加图书
    def add_book(self, book_id, title, author):
        book = Book(book_id, title, author, "available")
        self.books.append(book)
        print("图书添加成功！")

    # 借阅图书
    def borrow_book(self, book_id):
        for book in self.books:
            if book.book_id == book_id:
                if book.status == "available":
                    book.status = "borrowed"
                    print("借阅成功！")
                    return
                else:
                    print("该图书已被借出！")
                    return
        print("找不到该图书！")

    # 归还图书
    def return_book(self, book_id):
        for book in self.books:
            if book.book_id == book_id:
                if book.status == "borrowed":
                    book.status = "available"
                    print("归还成功！")
                    return
                else:
                    print("该图书已在库中！")
                    return
        print("找不到该图书！")

    # 查询图书
    def search_book(self, query):
        result = []
        for book in self.books:
            if query.lower() in book.title.lower() or query.lower() in book.author.lower():
                result.append(book)
        if len(result) == 0:
            print("未找到相关图书！")
        else:
            for book in result:
                print(f"书名：{book.title}，作者：{book.author}，状态：{book.status}")

你可以通过实例化 `Library` 类来创建一个图书馆对象，然后调用相应的方法来管理图书：

library = Library()

# 添加图书
library.add_book("001", "Python从入门到精通", "张三")
library.add_book("002", "Java从入门到精通", "李四")

# 借阅图书
library.borrow_book("001")
library.borrow_book("001") # 该图书已被借出！

# 归还图书
library.return_book("001")

# 查询图书
library.search_book("python")

希望能帮到你！