Project Structure

The system is organized into standard MVC layers:

• beans: entity classes (Book, User, Jbook)
• controller: request handling and menu navigation
• service: business logic itnerfaces
• service.impl: service implementations
• dao: data access layer (not fully shown)
• util: database connection helper

Code Implementation

Entity Classes

Book.java

package com.xszx.beans;

public class Book {
    private int id;
    private String name;
    private int bsum;

    public Book() {}

    public Book(int id, String name, int bsum) {
        this.id = id;
        this.name = name;
        this.bsum = bsum;
    }

    // getters and setters
    public int getId() { return id; }
    public void setId(int id) { this.id = id; }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public int getBsum() { return bsum; }
    public void setBsum(int bsum) { this.bsum = bsum; }

    @Override
    public String toString() {
        return "Book{id=" + id + ", name='" + name + '\'' + ", bsum=" + bsum + '}';
    }
}

Jbook.java (borrowing record)

package com.xszx.beans;

import java.util.Date;

public class Jbook {
    private int id;
    private int uid;
    private int bid;
    private Date jdate;
    private Date hdate;

    public Jbook() {}

    public Jbook(int id, int uid, int bid, Date jdate, Date hdate) {
        this.id = id;
        this.uid = uid;
        this.bid = bid;
        this.jdate = jdate;
        this.hdate = hdate;
    }

    // getters and setters
    public int getId() { return id; }
    public void setId(int id) { this.id = id; }
    public int getUid() { return uid; }
    public void setUid(int uid) { this.uid = uid; }
    public int getBid() { return bid; }
    public void setBid(int bid) { this.bid = bid; }
    public Date getJdate() { return jdate; }
    public void setJdate(Date jdate) { this.jdate = jdate; }
    public Date getHdate() { return hdate; }
    public void setHdate(Date hdate) { this.hdate = hdate; }

    @Override
    public String toString() {
        return "Jbook{id=" + id + ", uid=" + uid + ", bid=" + bid + ", jdate=" + jdate + ", hdate=" + hdate + '}';
    }
}

User.java

package com.xszx.beans;

public class User {
    private int id;
    private String username;
    private String password;
    private int role; // 1=admin, 2=member

    public User() {}

    public User(int id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }

    public User(int id, String username, String password, int role) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.role = role;
    }

    // getters and setters
    public int getId() { return id; }
    public void setId(int id) { this.id = id; }
    public String getUsername() { return username; }
    public void setUsername(String username) { this.username = username; }
    public String getPassword() { return password; }
    public void setPassword(String password) { this.password = password; }
    public int getRole() { return role; }
    public void setRole(int role) { this.role = role; }

    @Override
    public String toString() {
        return "User{id=" + id + ", username='" + username + '\'' + ", role=" + role + '}';
    }
}

Controller Layer

BookController.java

package com.xszx.controller;

import com.xszx.beans.Book;
import com.xszx.beans.Jbook;
import com.xszx.beans.User;
import com.xszx.service.BookService;
import com.xszx.service.JbookService;
import com.xszx.service.impl.BookServiceImpl;
import com.xszx.service.impl.JbookServiceImpl;
import java.util.List;
import java.util.Scanner;

public class BookController {
    private Scanner scanner = new Scanner(System.in);
    private BookService bookService = new BookServiceImpl();
    private JbookService jbookService = new JbookServiceImpl();

    public void adminMenu(User currentUser) {
        System.out.println("\n--- Admin Book Management ---");
        System.out.println("[1] View books [2] Add book [3] Edit book [4] Delete book [0] Back");
        int choice = scanner.nextInt();
        switch (choice) {
            case 1:
                displayBooks();
                adminMenu(currentUser);
                break;
            case 2:
                addNewBook();
                adminMenu(currentUser);
                break;
            case 3:
                updateBook();
                adminMenu(currentUser);
                break;
            case 4:
                removeBook();
                adminMenu(currentUser);
                break;
            case 0:
                new UserController().mainMenu(currentUser);
                break;
            default:
                System.out.println("Invalid input, try again.");
                adminMenu(currentUser);
        }
    }

    public void userMenu(User currentUser) {
        System.out.println("\n--- User Book System ---");
        System.out.println("[1] View books [2] Borrow book [3] Return book [4] View records [0] Back");
        int choice = scanner.nextInt();
        switch (choice) {
            case 1:
                displayBooks();
                userMenu(currentUser);
                break;
            case 2:
                borrowBook(currentUser);
                userMenu(currentUser);
                break;
            case 3:
                returnBook(currentUser);
                userMenu(currentUser);
                break;
            case 4:
                recordMenu(currentUser);
                break;
            case 0:
                new UserController().mainMenu(currentUser);
                break;
            default:
                System.out.println("Invalid input, try again.");
                userMenu(currentUser);
        }
    }

    private void recordMenu(User currentUser) {
        System.out.println("\n--- Borrow Records ---");
        System.out.println("[1] All records [2] Returned [3] Not returned [0] Back");
        int choice = scanner.nextInt();
        switch (choice) {
            case 1:
                showAllRecords(currentUser);
                recordMenu(currentUser);
                break;
            case 2:
                showReturnedRecords(currentUser);
                recordMenu(currentUser);
                break;
            case 3:
                showUnreturnedRecords(currentUser);
                recordMenu(currentUser);
                break;
            case 0:
                userMenu(currentUser);
                break;
            default:
                System.out.println("Invalid input.");
                recordMenu(currentUser);
        }
    }

    private void showAllRecords(User user) {
        List<Jbook> records = jbookService.getAllRecords(user);
        records.forEach(System.out::println);
    }

    private void showReturnedRecords(User user) {
        List<Jbook> records = jbookService.getReturnedRecords(user);
        records.forEach(System.out::println);
    }

    private void showUnreturnedRecords(User user) {
        List<Jbook> records = jbookService.getUnreturnedRecords(user);
        records.forEach(System.out::println);
    }

    private void returnBook(User user) {
        System.out.print("Enter book ID to return: ");
        int bid = scanner.nextInt();
        int recordId = bookService.findRecordByUserAndBook(user, bid);
        if (recordId > 0) {
            jbookService.processReturn(recordId);
            bookService.incrementStock(bid);
            bookService.updateReturnDate(bid);
            System.out.println("Book returned successfully.");
        } else {
            System.out.println("This book is not currently borrowed or does not need return.");
        }
    }

    private void borrowBook(User user) {
        System.out.print("Enter book ID to borrow: ");
        int bid = scanner.nextInt();
        if (bookService.isAvailable(bid)) {
            int existingRecord = bookService.findRecordByUserAndBook(user, bid);
            if (existingRecord > 0) {
                System.out.println("You have already borrowed this book and not returned it.");
            } else {
                jbookService.createBorrowRecord(user, bid);
                bookService.decrementStock(bid);
                bookService.updateBorrowDate(bid);
                System.out.println("Book borrowed successfully.");
            }
        } else {
            System.out.println("This book is out of stock or does not exist. Check the book list.");
        }
    }

    private void removeBook() {
        System.out.print("Enter book name to delete: ");
        Book target = new Book();
        target.setName(scanner.next());
        Book existing = bookService.findByName(target);
        if (existing != null) {
            int result = bookService.delete(target);
            if (result == 2) {
                System.out.println("Book deleted successfully.");
            } else if (result == 1) {
                System.out.println("Cannot delete: book is currently borrowed.");
            }
        } else {
            System.out.println("Book not found.");
        }
    }

    private void updateBook() {
        System.out.print("Enter book name to edit: ");
        Book original = new Book();
        original.setName(scanner.next());
        Book existing = bookService.findByName(original);
        if (existing != null) {
            System.out.print("Enter new book name: ");
            Book updated = new Book();
            updated.setName(scanner.next());
            int code = bookService.update(original, updated);
            if (code == 0) {
                System.out.println("Book updated.");
            } else {
                System.out.println("New name already exists.");
            }
        } else {
            System.out.println("Book not found.");
        }
    }

    private void addNewBook() {
        Book book = new Book();
        System.out.print("Enter book name: ");
        book.setName(scanner.next());
        Book existing = bookService.findByName(book);
        if (existing != null) {
            System.out.println("Book name conflict.");
            adminMenu(null);
        } else {
            System.out.print("Enter stock quantity: ");
            book.setBsum(scanner.nextInt());
            int result = bookService.add(book);
            if (result == 1) {
                System.out.println("Book added successfully.");
            } else {
                System.out.println("Failed to add book.");
            }
        }
    }

    private void displayBooks() {
        List<Book> books = bookService.getAll();
        books.forEach(System.out::println);
    }
}

UserController.java

package com.xszx.controller;

import com.xszx.beans.User;
import com.xszx.service.UserService;
import com.xszx.service.impl.UserServiceImpl;
import java.util.Scanner;

public class UserController {
    private Scanner scanner = new Scanner(System.in);
    private UserService userService = new UserServiceImpl();

    public void mainMenu(User currentUser) {
        System.out.println("\n--- Book Management System ---");
        System.out.println("[1] Login [2] Register [0] Exit");
        int choice = scanner.nextInt();
        switch (choice) {
            case 1:
                performLogin();
                break;
            case 2:
                performRegistration();
                break;
            case 0:
                System.out.println("System exited. Goodbye!");
                System.exit(0);
                break;
            default:
                System.out.println("Invalid input.");
                mainMenu(null);
        }
    }

    private void performRegistration() {
        User newUser = new User();
        System.out.print("Enter username: ");
        newUser.setUsername(scanner.next());
        if (userService.isRegistered(newUser)) {
            System.out.println("Username already exists.");
            mainMenu(null);
        } else {
            System.out.print("Enter password: ");
            newUser.setPassword(scanner.next());
            userService.addUser(newUser);
            System.out.println("Registration successful.");
            mainMenu(null);
        }
    }

    private User performLogin() {
        User credentials = new User();
        System.out.print("Enter username: ");
        credentials.setUsername(scanner.next());
        System.out.print("Enter password: ");
        credentials.setPassword(scanner.next());
        User loggedUser = userService.authenticate(credentials);
        if (loggedUser != null) {
            System.out.println("Login successful.");
            BookController controller = new BookController();
            if (loggedUser.getRole() == 1) {
                controller.adminMenu(loggedUser);
            } else {
                controller.userMenu(loggedUser);
            }
            return loggedUser;
        } else {
            System.out.println("Invalid credentials.");
            mainMenu(null);
            return null;
        }
    }
}

Service Interfaces

BookService.java

package com.xszx.service;

import com.xszx.beans.Book;
import com.xszx.beans.User;
import java.util.List;

public interface BookService {
    List<Book> getAll();
    int add(Book book);
    Book findByName(Book book);
    int update(Book original, Book updated);
    int delete(Book book);
    boolean isAvailable(int bid);
    int findRecordByUserAndBook(User user, int bid);
    void decrementStock(int bid);
    void updateBorrowDate(int bid);
    void incrementStock(int bid);
    void updateReturnDate(int bid);
}

JbookService.java

package com.xszx.service;

import com.xszx.beans.Jbook;
import com.xszx.beans.User;
import java.util.List;

public interface JbookService {
    void processReturn(int recordId);
    List<Jbook> getAllRecords(User user);
    List<Jbook> getReturnedRecords(User user);
    List<Jbook> getUnreturnedRecords(User user);
    void createBorrowRecord(User user, int bid);
}

UserService.java

package com.xszx.service;

import com.xszx.beans.User;

public interface UserService {
    User authenticate(User user);
    boolean isRegistered(User user);
    void addUser(User user);
}

Database Utility

JDBCUtil.java

package com.xszx.util;

import java.sql.*;

public class JDBCUtil {
    private static final String URL = "jdbc:mysql://127.0.0.1:3306/booksystem";
    private static final String DB_USER = "root";
    private static final String DB_PASSWORD = "123456";

    static {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    public static Connection getConnection() {
        try {
            return DriverManager.getConnection(URL, DB_USER, DB_PASSWORD);
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        }
    }

    public static void close(Connection conn, PreparedStatement ps, ResultSet rs) {
        try {
            if (rs != null) rs.close();
            if (ps != null) ps.close();
            if (conn != null) conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Note: The dao and service.impl layers are structurally similar with SQL query implementations. A MySQL database named booksystem must be created beforehand. This system is suitable for Java course projects in second or third year of university.