帮我写一个java程序：设计图书馆借阅系统

在Java中，我们可以设计一个简单的图书馆借阅系统的类结构，包含图书、读者和图书馆等核心组件。以下是一个基础的示例：

// 定义图书类Book
class Book {
    private String title;
    private String author;
    private boolean isAvailable;

    // 构造函数、getter和setter方法
    public Book(String title, String author) {
        this.title = title;
        this.author = author;
        this.isAvailable = true;
    }

    // 其他方法如借书、还书操作...
}

// 定义读者类Reader
class Reader {
    private String id;
    private String name;

    // 构造函数、getter和setter方法
    public Reader(String id, String name) {
        this.id = id;
        this.name = name;
    }

    // 借书方法，检查书籍可用并更新状态
    public void borrow(Book book) {
        if (book.isAvailable()) {
            System.out.println(name + " borrowed " + book.getTitle());
            book.setAvailable(false);
        } else {
            System.out.println(book.getTitle() + " is not available.");
        }
    }

    // 还书方法，恢复书籍状态
    public void returnBook(Book book) {
        System.out.println(name + " returned " + book.getTitle());
        book.setAvailable(true);
    }
}

// 定义图书馆类Library
class Library {
    private Map<String, Book> books;

    // 构造函数和获取书籍的方法
    public Library() {
        books = new HashMap<>();
        // 添加书籍到图书馆...
    }

    // 添加读者和借阅操作...
}

public class Main {
    public static void main(String[] args) {
        Library library = new Library();
        Reader reader = new Reader("001", "Alice");

        // 读者操作，例如借书和还书
        Book book = new Book("The Great Gatsby", "F. Scott Fitzgerald");
        reader.borrow(book);
        reader.returnBook(book);

        // 更多复杂功能可以在此基础上添加，比如借阅历史记录、逾期处理等...
    }
}