Java如何做一个简易图书馆借阅系统_附完整逻辑结构与实现思路

import java.util.*;

// 图书类
class Book {
    private String id;
    private String title;
    private String author;
    private boolean available;

    public Book(String id, String title, String author) {
        this.id = id;
        this.title = title;
        this.author = author;
        this.available = true;
    }

    // getter 和 setter 方法
    public String getId() { return id; }
    public String getTitle() { return title; }
    public String getAuthor() { return author; }
    public boolean isAvailable() { return available; }
    public void setAvailable(boolean available) { this.available = available; }

    @Override
    public String toString() {
        return "Book{" +
                "id='" + id + '\'' +
                ", title='" + title + '\'' +
                ", author='" + author + '\'' +
                ", available=" + (available ? "可借" : "已借出") +
                '}';
    }
}

// 读者类
class Reader {
    private String id;
    private String name;
    private List<Book> borrowedBooks;

    public Reader(String id, String name) {
        this.id = id;
        this.name = name;
        this.borrowedBooks = new ArrayList<>();
    }

    public String getId() { return id; }
    public String getName() { return name; }
    public List<Book> getBorrowedBooks() { return borrowedBooks; }

    // 借书
    public void borrowBook(Book book) {
        borrowedBooks.add(book);
    }

    // 还书
    public boolean returnBook(String bookId) {
        Book toRemove = null;
        for (Book b : borrowedBooks) {
            if (b.getId().equals(bookId)) {
                toRemove = b;
                break;
            }
        }
        if (toRemove != null) {
            borrowedBooks.remove(toRemove);
            return true;
        }
        return false;
    }

    @Override
    public String toString() {
        return "Reader{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", borrowedBooksCount=" + borrowedBooks.size() +
                '}';
    }
}

// 图书馆管理类
public class Library {
    private List<Book> books;
    private List<Reader> readers;

    public Library() {
        this.books = new ArrayList<>();
        this.readers = new ArrayList<>();
    }

    // 添加图书
    public void addBook(Book book) {
        books.add(book);
        System.out.println("图书已添加：" + book.getTitle());
    }

    // 注册读者
    public void registerReader(Reader reader) {
        readers.add(reader);
        System.out.println("读者已注册：" + reader.getName());
    }

    // 借书
    public void borrowBook(String readerId, String bookId) {
        Reader reader = findReaderById(readerId);
        Book book = findBookById(bookId);

        if (reader == null) {
            System.out.println("错误：读者不存在！");
            return;
        }
        if (book == null) {
            System.out.println("错误：图书不存在！");
            return;
        }
        if (!book.isAvailable()) {
            System.out.println("抱歉，《" + book.getTitle() + "》已被借出。");
            return;
        }

        book.setAvailable(false);
        reader.borrowBook(book);
        System.out.println("借阅成功：" + reader.getName() + " 借了《" + book.getTitle() + "》");
    }

    // 还书
    public void returnBook(String readerId, String bookId) {
        Reader reader = findReaderById(readerId);
        Book book = findBookById(bookId);

        if (reader == null || book == null) {
            System.out.println("读者或图书信息错误！");
            return;
        }

        boolean success = reader.returnBook(bookId);
        if (success) {
            book.setAvailable(true);
            System.out.println("还书成功：" + reader.getName() + " 归还了《" + book.getTitle() + "》");
        } else {
            System.out.println("该读者未借阅此书！");
        }
    }

    // 查询所有图书
    public void listAllBooks() {
        System.out.println("\n=== 所有图书 ===");
        for (Book book : books) {
            System.out.println(book);
        }
    }

    // 查询所有读者及借书情况
    public void listAllReaders() {
        System.out.println("\n=== 所有读者 ===");
        for (Reader reader : readers) {
            System.out.println(reader);
            if (!reader.getBorrowedBooks().isEmpty()) {
                System.out.println("  已借图书：");
                for (Book b : reader.getBorrowedBooks()) {
                    System.out.println("    - " + b.getTitle());
                }
            }
        }
    }

    // 辅助方法：根据ID查找图书
    private Book findBookById(String id) {
        for (Book b : books) {
            if (b.getId().equals(id)) {
                return b;
            }
        }
        return null;
    }

    // 辅助方法：根据ID查找读者
    private Reader findReaderById(String id) {
        for (Reader r : readers) {
            if (r.getId().equals(id)) {
                return r;
            }
        }
        return null;
    }

    // 主方法演示
    public static void main(String[] args) {
        Library lib = new Library();
        Scanner sc = new Scanner(System.in);

        // 初始化几本书和读者
        Book b1 = new Book("B001", "Java编程思想", "Bruce Eckel");
        Book b2 = new Book("B002", "算法导论", "Cormen");
        lib.addBook(b1);
        lib.addBook(b2);

        Reader r1 = new Reader("R001", "张三");
        Reader r2 = new Reader("R002", "李四");
        lib.registerReader(r1);
        lib.registerReader(r2);

        while (true) {
            System.out.println("\n--- 图书馆系统 ---");
            System.out.println("1. 借书");
            System.out.println("2. 还书");
            System.out.println("3. 查看所有图书");
            System.out.println("4. 查看所有读者");
            System.out.println("5. 退出");
            System.out.print("请选择操作：");
            int choice = sc.nextInt();
            sc.nextLine(); // 消费换行

            switch (choice) {
                case 1:
                    System.out.print("输入读者ID: ");
                    String rid = sc.nextLine();
                    System.out.print("输入图书ID: ");
                    String bid = sc.nextLine();
                    lib.borrowBook(rid, bid);
                    break;
                case 2:
                    System.out.print("输入读者ID: ");
                    rid = sc.nextLine();
                    System.out.print("输入图书ID: ");
                    bid = sc.nextLine();
                    lib.returnBook(rid, bid);
                    break;
                case 3:
                    lib.listAllBooks();
                    break;
                case 4:
                    lib.listAllReaders();
                    break;
                case 5:
                    System.out.println("再见！");
                    sc.close();
                    return;
                default:
                    System.out.println("无效选择！");
            }
        }
    }
}