写一个图书借阅管理系统的代码

这取决于系统的功能和设计，但以下是一个简单的图书借阅管理系统的代码示例：// 定义类：Library
class Library {
// 定义类变量
int totalBooks;
int totalUsers;
// 定义构造函数
Library(){
totalBooks = 0;
totalUsers = 0;
}
// 定义函数：增加图书
void addBook(){
totalBooks++;
}
// 定义函数：增加用户
void addUser(){
totalUsers++;
}
// 定义函数：借阅图书
void lendBook(){
if(totalBooks > 0 && totalUsers > 0){
totalBooks--;
totalUsers--;
}
}
// 定义函数：还书
void returnBook(){
totalBooks++;
}
}

相关问题

写一个图书借阅管理系统

以下是一个简单的图书借阅管理系统的Java代码示例，包括读者和管理员两种账号类型的功能：

import java.util.ArrayList;
import java.util.Scanner;

public class LibrarySystem {
    private ArrayList<Book> books;
    private ArrayList<Reader> readers;
    private ArrayList<BorrowRecord> records;
    private Scanner scanner;

    public LibrarySystem() {
        books = new ArrayList<>();
        readers = new ArrayList<>();
        records = new ArrayList<>();
        scanner = new Scanner(System.in);
    }

    public void run() {
        while (true) {
            System.out.println("欢迎使用图书借阅管理系统！");
            System.out.println("请选择登录类型：1.读者 2.管理员");
            int type = scanner.nextInt();
            if (type == 1) {
                Reader reader = loginAsReader();
                if (reader != null) {
                    readerMenu(reader);
                }
            } else if (type == 2) {
                Admin admin = loginAsAdmin();
                if (admin != null) {
                    adminMenu(admin);
                }
            } else {
                System.out.println("输入错误，请重新选择！");
            }
        }
    }

    private Reader loginAsReader() {
        System.out.println("请输入读者账号：");
        String account = scanner.next();
        System.out.println("请输入密码：");
        String password = scanner.next();
        for (Reader reader : readers) {
            if (reader.getAccount().equals(account) && reader.getPassword().equals(password)) {
                System.out.println("登录成功！");
                return reader;
            }
        }
        System.out.println("账号或密码错误，登录失败！");
        return null;
    }

    private void readerMenu(Reader reader) {
        while (true) {
            System.out.println("请选择操作：1.查找图书 2.借阅图书 3.还书 4.查看历史借阅记录 5.修改个人资料 6.修改密码 7.退出登录");
            int choice = scanner.nextInt();
            switch (choice) {
                case 1:
                    searchBooks();
                    break;
                case 2:
                    borrowBook(reader);
                    break;
                case 3:
                    returnBook(reader);
                    break;
                case 4:
                    viewBorrowRecords(reader);
                    break;
                case 5:
                    modifyReaderInfo(reader);
                    break;
                case 6:
                    modifyReaderPassword(reader);
                    break;
                case 7:
                    System.out.println("退出登录成功！");
                    return;
                default:
                    System.out.println("输入错误，请重新选择！");
            }
        }
    }

    private Admin loginAsAdmin() {
        System.out.println("请输入管理员账号：");
        String account = scanner.next();
        System.out.println("请输入密码：");
        String password = scanner.next();
        for (Admin admin : admins) {
            if (admin.getAccount().equals(account) && admin.getPassword().equals(password)) {
                System.out.println("登录成功！");
                return admin;
            }
        }
        System.out.println("账号或密码错误，登录失败！");
        return null;
    }

    private void adminMenu(Admin admin) {
        while (true) {
            System.out.println("请选择操作：1.添加图书 2.修改图书 3.删除图书 4.添加读者 5.修改读者 6.删除读者 7.查看借阅记录 8.退出登录");
            int choice = scanner.nextInt();
            switch (choice) {
                case 1:
                    addBook();
                    break;
                case 2:
                    modifyBook();
                    break;
                case 3:
                    deleteBook();
                    break;
                case 4:
                    addReader();
                    break;
                case 5:
                    modifyReader();
                    break;
                case 6:
                    deleteReader();
                    break;
                case 7:
                    viewBorrowRecords();
                    break;
                case 8:
                    System.out.println("退出登录成功！");
                    return;
                default:
                    System.out.println("输入错误，请重新选择！");
            }
        }
    }

    private void searchBooks() {
        System.out.println("请输入关键字：");
        String keyword = scanner.next();
        ArrayList<Book> result = new ArrayList<>();
        for (Book book : books) {
            if (book.getTitle().contains(keyword) || book.getAuthor().contains(keyword)) {
                result.add(book);
            }
        }
        if (result.isEmpty()) {
            System.out.println("未找到相关图书！");
        } else {
            System.out.println("共找到" + result.size() + "本图书：");
            for (Book book : result) {
                System.out.println(book);
            }
        }
    }

    private void borrowBook(Reader reader) {
        System.out.println("请输入要借阅的图书编号：");
        int bookId = scanner.nextInt();
        Book book = findBookById(bookId);
        if (book == null) {
            System.out.println("未找到该图书！");
        } else if (book.isBorrowed()) {
            System.out.println("该图书已被借出！");
        } else {
            book.setBorrowed(true);
            BorrowRecord record = new BorrowRecord(reader, book);
            records.add(record);
            System.out.println("借阅成功！");
        }
    }

    private void returnBook(Reader reader) {
        System.out.println("请输入要归还的图书编号：");
        int bookId = scanner.nextInt();
        Book book = findBookById(bookId);
        if (book == null) {
            System.out.println("未找到该图书！");
        } else if (!book.isBorrowed()) {
            System.out.println("该图书未被借出！");
        } else {
            book.setBorrowed(false);
            for (BorrowRecord record : records) {
                if (record.getReader() == reader && record.getBook() == book) {
                    record.setReturned(true);
                    System.out.println("归还成功！");
                    return;
                }
            }
            System.out.println("归还失败！");
        }
    }

    private void viewBorrowRecords(Reader reader) {
        ArrayList<BorrowRecord> result = new ArrayList<>();
        for (BorrowRecord record : records) {
            if (record.getReader() == reader) {
                result.add(record);
            }
        }
        if (result.isEmpty()) {
            System.out.println("未找到历史借阅记录！");
        } else {
            System.out.println("共找到" + result.size() + "条历史借阅记录：");
            for (BorrowRecord record : result) {
                System.out.println(record);
            }
        }
    }

    private void modifyReaderInfo(Reader reader) {
        System.out.println("请输入新的姓名：");
        String name = scanner.next();
        System.out.println("请输入新的性别：");
        String gender = scanner.next();
        System.out.println("请输入新的年龄：");
        int age = scanner.nextInt();
        reader.setName(name);
        reader.setGender(gender);
        reader.setAge(age);
        System.out.println("修改成功！");
    }

    private void modifyReaderPassword(Reader reader) {
        System.out.println("请输入旧密码：");
        String oldPassword = scanner.next();
        System.out.println("请输入新密码：");
        String newPassword = scanner.next();
        if (reader.getPassword().equals(oldPassword)) {
            reader.setPassword(newPassword);
            System.out.println("修改成功！");
        } else {
            System.out.println("密码错误，修改失败！");
        }
    }

    private void addBook() {
        System.out.println("请输入图书编号：");
        int id = scanner.nextInt();
        System.out.println("请输入图书名称：");
        String title = scanner.next();
        System.out.println("请输入作者名称：");
        String author = scanner.next();
        Book book = new Book(id, title, author);
        books.add(book);
        System.out.println("添加成功！");
    }

    private void modifyBook() {
        System.out.println("请输入要修改的图书编号：");
        int id = scanner.nextInt();
        Book book = findBookById(id);
        if (book == null) {
            System.out.println("未找到该图书！");
        } else {
            System.out.println("请输入新的图书名称：");
            String title = scanner.next();
            System.out.println("请输入新的作者名称：");
            String author = scanner.next();
            book.setTitle(title);
            book.setAuthor(author);
            System.out.println("修改成功！");
        }
    }

    private void deleteBook() {
        System.out.println("请输入要删除的图书编号：");
        int id = scanner.nextInt();
        Book book = findBookById(id);
        if (book == null) {
            System.out.println("未找到该图书！");
        } else if (book.isBorrowed()) {
            System.out.println("该图书已被借出，无法删除！");
        } else {
            books.remove(book);
            System.out.println("删除成功！");
        }
    }

    private void addReader() {
        System.out.println("请输入读者账号：");
        String account = scanner.next();
        System.out.println("请输入密码：");
        String password = scanner.next();
        System.out.println("请输入姓名：");
        String name = scanner.next();
        System.out.println("请输入性别：");
        String gender = scanner.next();
        System.out.println("请输入年龄：");
        int age = scanner.nextInt();
        Reader reader = new Reader(account, password, name, gender, age);
        readers.add(reader);
        System.out.println("添加成功！");
    }

    private void modifyReader() {
        System.out.println("请输入要修改的读者账号：");
        String account = scanner.next();
        Reader reader = findReaderByAccount(account);
        if (reader == null) {
            System.out.println("未找到该读者！");
        } else {
            System.out.println("请输入新的密码：");
            String password = scanner.next();
            System.out.println("请输入新的姓名：");
            String name = scanner.next();
            System.out.println("请输入新的性别：");
            String gender = scanner.next();
            System.out.println("请输入新的年龄：");
            int age = scanner.nextInt();
            reader.setPassword(password);
            reader.setName(name);
            reader.setGender(gender);
            reader.setAge(age);
            System.out.println("修改成功！");
        }
    }

    private void deleteReader() {
        System.out.println("请输入要删除的读者账号：");
        String account = scanner.next();
        Reader reader = findReaderByAccount(account);
        if (reader == null) {
            System.out.println("未找到该读者！");
        } else if (hasBorrowedBooks(reader)) {
            System.out.println("该读者还有未归还的图书，无法删除！");
        } else {
            readers.remove(reader);
            System.out.println("删除成功！");
        }
    }

    private void viewBorrowRecords() {
        if (records.isEmpty()) {
            System.out.println("暂无借阅记录！");
        } else {
            System.out.println("共有" + records.size() + "条借阅记录：");
            for (BorrowRecord record : records) {
                System.out.println(record);
            }
        }
    }

    private Book findBookById(int id) {
        for (Book book : books) {
            if (book.getId() == id) {
                return book;
            }
        }
        return null;
    }

    private Reader findReaderByAccount(String account) {
        for (Reader reader : readers) {
            if (reader.getAccount().equals(account)) {
                return reader;
            }
        }
        return null;
    }

    private boolean hasBorrowedBooks(Reader reader) {
        for (BorrowRecord record : records) {
            if (record.getReader() == reader && !record.isReturned()) {
                return true;
            }
        }
        return false;
    }
}

class Book {
    private int id;
    private String title;
    private String author;
    private boolean borrowed;

    public Book(int id, String title, String author) {
        this.id = id;
        this.title = title;
        this.author = author;
        borrowed = false;
    }

    public int getId() {
        return id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public boolean isBorrowed() {
        return borrowed;
    }

    public void setBorrowed(boolean borrowed) {
        this.borrowed = borrowed;
    }

    @Override
    public String toString() {
        return "编号：" + id + "，书名：" + title + "，作者：" + author + "，状态：" + (borrowed ? "已借出" : "未借出");
    }
}

class Reader {
    private String account;
    private String password;
    private String name;
    private String gender;
    private int age;

    public Reader(String account, String password, String name, String gender, int age) {
        this.account = account;
        this.password = password;
        this.name = name;
        this.gender = gender;
        this.age = age;
    }

    public String getAccount() {
        return account;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name =

用sql写一个图书借阅管理系统

好的，以下是一个简单的图书借阅管理系统的 SQL：

CREATE TABLE books (
    id INT PRIMARY KEY,
    title VARCHAR(255) NOT NULL,
    author VARCHAR(255) NOT NULL,
    publish_date DATE NOT NULL,
    total INT NOT NULL,
    available INT NOT NULL
);

CREATE TABLE borrowers (
    id INT PRIMARY KEY,
    name VARCHAR(255) NOT NULL,
    email VARCHAR(255) NOT NULL,
    phone VARCHAR(20) NOT NULL
);

CREATE TABLE borrowings (
    id INT PRIMARY KEY,
    book_id INT NOT NULL,
    borrower_id INT NOT NULL,
    borrow_date DATE NOT NULL,
    return_date DATE,
    FOREIGN KEY (book_id) REFERENCES books(id),
    FOREIGN KEY (borrower_id) REFERENCES borrowers(id)
);

这里我们创建了三个表：

- `books` 表存储了所有的图书信息，包括书名、作者、出版日期、总数以及可供借阅的数量。
- `borrowers` 表存储了所有的借阅者信息，包括姓名、邮箱、电话等。
- `borrowings` 表记录了每一次借阅的具体信息，包括所借图书的 ID、借阅者的 ID、借阅日期和归还日期。

接下来，我们可以通过以下 SQL 语句来实现一些基本的操作：

- 向 books 表中添加新的图书记录：

  INSERT INTO books (id, title, author, publish_date, total, available)
  VALUES (1, 'The Great Gatsby', 'F. Scott Fitzgerald', '1925-04-10', 5, 5);

- 向 borrowers 表中添加新的借阅者记录：

  INSERT INTO borrowers (id, name, email, phone)
  VALUES (1, 'John Smith', 'john.smith@example.com', '555-1234');

- 向 borrowings 表中添加新的借阅记录：

  INSERT INTO borrowings (id, book_id, borrower_id, borrow_date, return_date)
  VALUES (1, 1, 1, '2021-01-01', NULL);

- 查询所有在借图书：

  SELECT books.title, books.author, borrowings.borrow_date, borrowings.return_date
  FROM borrowings
  INNER JOIN books ON borrowings.book_id = books.id
  WHERE borrowings.return_date IS NULL;

- 查询某个借阅者借了哪些书：

  SELECT books.title, books.author, borrowings.borrow_date, borrowings.return_date
  FROM borrowings
  INNER JOIN books ON borrowings.book_id = books.id
  WHERE borrowings.borrower_id = 1;

- 更新 borrowings 表中某条借阅记录的归还日期：

  UPDATE borrowings
  SET return_date = '2021-02-01'
  WHERE id = 1;

以上是一个简单的图书借阅管理系统的 SQL 实现，实际应用中可能会更加复杂，但是这里提供的代码可以作为一个基本的参考。