Java實現簡單圖書館管理系統

編寫圖書館管理系統

思路

要編寫這個程序我們首相要清楚這個程序中有哪些對象,不考慮複雜情況，基本的對象有三個：

1. 書
2. 用戶

那麼我們就分別討論這三個對象有哪些屬性和有哪些動作。

1. 書籍 它會有書名，編號(id)， 作者， 類別， 價格， 是否被借 這些簡單的屬性
2. 用戶包括：管理員和普通用戶，管理員它會有姓名， 增加書籍， 刪除書籍， 查找書籍， 打印所有書籍信息， 退出系統 這些簡單屬性。
   普通用戶它會有姓名， 查找書籍， 借閱書籍， 歸還書籍， 退出系統這些簡單的屬性。

我們把這三個對象分別放入三個包中，這樣在分別完成這些對象中所需的動作(方法)。
我們書籍包中的代碼：

package book;

public class Book {
    private String name;
    private String id;
    private String author;
    private String type;
    private int price;
    private boolean isBorrow;

    public Book(String name, String id, String author, String type, int price, boolean isBorrow) {
        this.name = name;
        this.id = id;
        this.author = author;
        this.type = type;
        this.price = price;
        this.isBorrow = isBorrow;
    }

    public String getId() {
        return id;
    }

    public boolean isBorrow() {
        return isBorrow;
    }

    public void setBorrow(boolean borrow) {
        isBorrow = borrow;
    }

    public String getName() {
        return name;
    }

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

同時創建一個類似順序表的書籍數組保存書籍。

package book;

public class BookList {
    private Book[] books = new Book[100];
    private int size;

    public BookList() {
        books[0] = new Book("金瓶梅",
                "001", "蘭陵笑笑生","古典名著",
                100, false);
        books[1] = new Book("水滸傳",
                "002", "施耐庵","古典名著",
                100, false);
        books[2] = new Book("西遊記",
                "003", "吳承恩","古典名著",
                100, false);
        size = 3;
    }

    public int getSize() {
        return size;
    }

    public void setSize(int size) {
        this.size = size;
    }

    public Book getBook(int index) {
        return books[index];
    }

    public void setBooks(int index, Book book) {
        books[index] = book;
    }
}

我們將用所有的操作方法放入operation包中，所有的方法都用接口來實現，這樣我們就避免了使用一大堆的 if else

接口：

package operation;

import book.BookList;

public interface IOperation {
    void work(BookList bookList);
}

增加新書籍：

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class AddBookOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("新增一本書籍!");
        System.out.println("請輸入新增書籍的書名: ");
        Scanner scanner = new Scanner(System.in);
        String name = scanner.next();
        System.out.println("請輸入新增書籍的id: ");
        String id = scanner.next();
        System.out.println("請輸入新增書籍的作者: ");
        String author = scanner.next();
        System.out.println("請輸入新增書籍的類型: ");
        String type = scanner.next();
        System.out.println("請輸入新增書籍的價格: ");
        int price = scanner.nextInt();
        Book book = new Book(name, id, author, type, price, false);
        bookList.setBooks(bookList.getSize(), book);
        bookList.setSize(bookList.getSize() + 1);
    }
}

刪除書籍：

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class DeleteBookOperation implements IOperation {
    @Override
    public void work(BookList bookList) {
        System.out.println("刪除書籍!");
        System.out.println("請輸入您想要刪除書籍的id: ");
        Scanner scanner = new Scanner(System.in);
        String id = scanner.next();
        int i = 0;
        for (; i < bookList.getSize(); i++) {
            Book book = bookList.getBook(i);
            if (book.getId().equals(id)) {
                break;
            }
        }
        if (i >= bookList.getSize()) {
            System.out.println("未找到要找的書籍!");
            return;
        }

        Book lastBook = bookList.getBook(bookList.getSize() - 1);
        bookList.setBooks(i, lastBook);
        bookList.setSize(bookList.getSize() - 1);
        System.out.println("刪除成功!");
    }
}

查找書籍：

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class FindOperation implements IOperation {
    @Override
    public void work(BookList bookList) {
        System.out.println("查找書籍!");
        System.out.println("請輸入要查找書籍的書名: ");
        Scanner scanner = new Scanner(System.in);
        String name = scanner.next();
        int count = 0;
        for (int i = 0; i < bookList.getSize(); i++) {
            Book book = bookList.getBook(i);
            if (book.getName().equals(name)) {
                System.out.println(book);
                count++;
            }
        }
        if (count == 0) {
            System.out.println("沒找到此書籍!");
        } else {
            System.out.println("共找到 " + count + " 本相同書籍!");
        }
    }
}

借閱書籍：

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class BorrowOperation implements IOperation {
    @Override
    public void work(BookList bookList) {
        System.out.println("借閱書籍!");
        System.out.println("請輸入要借閱的書籍的id: ");
        Scanner scanner = new Scanner(System.in);
        String id = scanner.next();

        for (int i = 0; i < bookList.getSize(); i++) {
            Book book = bookList.getBook(i);
            if (!book.getId().equals(id)) {
                continue;
            }
            if (book.isBorrow()) {
                System.out.println("此書已經被借走了!");
                break;
            }
            book.setBorrow(true);
            System.out.println("借閱成功");
        }
    }
}

歸還書籍：

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class ReturnOperation implements IOperation {
    @Override
    public void work(BookList bookList) {
        System.out.println("歸還書籍!");
        System.out.println("請輸入要歸還書籍的id: ");
        Scanner scanner = new Scanner(System.in);
        String id = scanner.next();
        int i = 0;
        for ( ; i < bookList.getSize(); i++) {
            Book book = bookList.getBook(i);
            if (!book.getId().equals(id)) {
                continue;
            }
            if (!book.isBorrow()) {
                System.out.println("這本書未借出去,歸還失敗!");
            }
            book.setBorrow(false);
        }
    }
}

打印所有書籍信息：

package operation;

import book.BookList;

public class PrintAllOperation implements IOperation {
    @Override
    public void work(BookList bookList) {
        for (int i = 0; i < bookList.getSize(); i++) {
            System.out.println(bookList.getBook(i));
        }
        System.out.println("共有 " + bookList.getSize() + " 本書籍");
    }
}

退出系統：

package operation;

import book.BookList;

public class ExitOperation implements  IOperation {
    @Override
    public void work(BookList bookList) {
        System.out.println("GoodBye!");
        System.exit(0);
    }
}

我們用戶中先創建一個抽象的用戶，再將不同用戶通過實現這個抽象的用戶來實現不同用戶的操作權限。
我們用戶包中的代碼
抽象的用戶代碼：

package user;

import book.BookList;
import operation.IOperation;

abstract public class User {
    protected String name;

    protected IOperation[] operations;

    public User(String name) {
        this.name = name;
    }

    abstract public int menu();

    public void doOperation(int choice, BookList bookList) {
        operations[choice].work(bookList);
    }
}

管理員用戶：

package user;

import book.BookList;
import operation.*;

import java.util.Scanner;

public class Admin extends User{
    public Admin(String name) {
        super(name);
        operations = new IOperation[] {
                new ExitOperation(),
                new AddBookOperation(),
                new DeleteBookOperation(),
                new FindOperation(),
                new PrintAllOperation(),
        };
    }

    @Override
    public int menu() {
        System.out.println("============");
        System.out.println("hello " + name);
        System.out.println("1. 增加書籍");
        System.out.println("2. 刪除書籍");
        System.out.println("3. 查找書籍");
        System.out.println("4. 打印所有信息");
        System.out.println("0. 退出");
        System.out.println("============");
        System.out.println("請輸入您的選擇: ");
        Scanner scanner = new Scanner(System.in);
        int choice = scanner.nextInt();
        return choice;
    }
}

普通用戶：

package user;

import operation.*;

import java.util.Scanner;

public class NormalUser extends  User {
    public NormalUser(String name) {
        super(name);
        operations = new IOperation[] {
                new ExitOperation(),
                new FindOperation(),
                new BorrowOperation(),
                new ReturnOperation(),
        };
    }

    @Override
    public int menu() {
        System.out.println("============");
        System.out.println("hello " + name);
        System.out.println("1. 查找圖書");
        System.out.println("2. 借閱圖書");
        System.out.println("3. 歸還圖書");
        System.out.println("0. 退出");
        System.out.println("============");
        System.out.println("請輸入您的選擇: ");
        Scanner scanner = new Scanner(System.in);
        int choice = scanner.nextInt();
        return choice;
    }
}

這樣就完成了一個簡單的圖書館管理系統。

這是測試類代碼塊

import book.BookList;
import user.Admin;
import user.NormalUser;
import user.User;

import java.util.Scanner;

public class Test {
    public static void main(String[] args) {
        BookList bookList = new BookList();
        User user = login();
        while (true) {
            int choice = user.menu();
            user.doOperation(choice, bookList);
        }
    }

    public static User login() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("歡迎來到圖書管理系統!");
        System.out.println("請輸入您的姓名: ");
        String name = scanner.next();
        System.out.println("請輸入您的用戶選項: 1 -> 管理員  2 -> 普通用戶");
        int role = scanner.nextInt();
        if (role == 1) {
            return new Admin(name);
        } else {
            return new NormalUser(name);
        }
    }


}

---

新增登錄、註冊模塊
創建dao包

我們的用戶User類，包含用戶名， 密碼

package dao;

public class User {
    String username;
    String password;

    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;
    }
}

UserDao包含登錄和註冊

package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class UserDao {


    //註冊
    public void login(User user) {
        Connection connection = DBUtil.getConnection();
        PreparedStatement statement = null;
        String sql = "insert into user values(?, ?)";

        try {
            statement = connection.prepareStatement(sql);
            statement.setString(1, user.getUsername());
            statement.setString(2, user.getPassword());
            int ret = statement.executeUpdate();
            if (ret != 1) {
                System.out.println("當前數據庫執行插入數據出錯");
                return;
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            DBUtil.close(connection, statement, null);
        }
    }

    //登錄
    public int enter(String username, String password) {
        List<String> list = new ArrayList<>();
        Connection connection = DBUtil.getConnection();
        String sql = "select username, password from user where username = ?";
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        int ret = 0;
        try {
            statement = connection.prepareStatement(sql);
            statement.setString(1, username);
            while (resultSet.next()) {
                String pass = resultSet.getString(password);
                list.add(pass);
            }
            if (list.contains(password)) {
                ret = 1;
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            DBUtil.close(connection, statement, resultSet);
        }
        return ret;
    }
}

DBUtil實現連接數據庫

package dao;

import java.sql.*;

public class DBUtil {
    private static final String URL = "jdbc:mysql://localhost:3306/java_github_crawler";

    private static final String USERNAME = "root";

    private static final String PASSWORD = "123456";

    private static Connection conn = null;
    static{
        try {
            //1.加載驅動程序
            Class.forName("com.mysql.jdbc.Driver");
            //2. 獲得數據庫連接
            conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static Connection getConnection(){
        return conn;
    }


    //釋放資源
    public static void close(Connection connection, Statement statement, ResultSet resultSet) {
        try {
            if (resultSet != null) {
                resultSet.close();
            }
            if (statement != null) {
                statement.close();
            }
            if (connection != null) {
                connection.close();
            }
        } catch (Exception e) {
            throw new RuntimeException("釋放數據庫資源失敗", e);
        }
    }

}

新的測試類：

import book.BookList;
import dao.UserDao;
import user.Admin;
import user.NormalUser;
import user.User;

import java.util.Scanner;

public class Test {
    public static void main(String[] args) {
        BookList bookList = new BookList();
        User user = login();
        if (user == null) {
            return;
        }
        while (true) {
            int choice = user.menu();
            user.doOperation(choice, bookList);
        }
    }

    public static User login() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("歡迎來到圖書管理系統!");
        dao.User user = new dao.User();
        System.out.println("請輸入您的用戶選項: 1 -> 註冊  2 -> 登錄");
        int role = scanner.nextInt();
        UserDao userDao = new UserDao();
        boolean isEnter = false;
        if (role == 1) {
            System.out.println("請輸入用戶名: ");
            user.setUsername(scanner.nextLine());
            System.out.println("請輸入密碼: ");
            user.setPassword(scanner.nextLine());
            userDao.login(user);
        } else {
            for (int i = 3; i >= 0; i--) {
                System.out.println("請輸入用戶名: ");
                String username = scanner.nextLine();
                System.out.println("請輸入密碼: ");
                String password = scanner.nextLine();
                int ret = userDao.enter(username, password);
                if (ret != 1) {
                    System.out.println("登錄失敗,您還有 " + i + "次機會");
                } else {
                    System.out.println("登錄成功");
                    isEnter = true;
                    break;
                }
            }
        }
        if (!isEnter) {
            return null;
        }

        String name = user.getUsername();
        System.out.println("請輸入您的用戶選項: 1 -> 管理員  2 -> 普通用戶");

        if (role == 1) {
            return new Admin(name);
        } else {
            return new NormalUser(name);
        }
    }


}