Java：命令行界面的图书管理系统

图书管理系统，相信大家都不陌生。借书还书等等操作...那么如何用Java来实现呢？

首先，我们从中抽取出一个个对象。

• 管理员的操作：
• 查看某个书籍、新增书籍、删除书籍、打印书籍列表、退出系统。
• 普通用户的操作：
• 查看某个书籍的信息、借阅书籍、归还书籍、退出系统。
• 当然，除了上面这些彩色标注的字样，最重要的还要实现书、书籍列表。

Book

• 属性：书名、作者、价格、类型、是否被借（为了封装尽量使用private）
• 方法：构造方法（用来初始化）、获取书名、获取被借状态、设置被借状态、toString

public class Book {
    private String name;
    private String author;
    private double price;
    private String type;
    private boolean isBorrowed=false;

    //构造方法，创建实例时初始化变量
    public Book(String name, String author, double price, String type) {
        this.name = name;
        this.author = author;
        this.price = price;
        this.type = type;
    }

    public String getName() {
        return name;
    }

    public boolean isBorrowed() {
        return isBorrowed;
    }

    public void setBorrowed(boolean borrowed) {
        isBorrowed = borrowed;
    }

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

BookList

• 属性：书籍列表的长度、列表的最大长度、Book类型的数组
• 方法：构造方法、获取列表长度、设置列表长度、得到指定下标的书、设置指定下标的书

//书籍列表
public class BookList {
    private int size;
    private int capacity=100;
    Book[] books=new Book[capacity];

    public BookList() {
        books[0]=new Book("西游记","吴承恩",50,"古典文学");
        books[1]=new Book("三国演义","罗贯中",60,"古典文学");
        books[2]=new Book("从你的全世界路过","张嘉佳",45,"青春文学");
        size=3;
    }

    public int getSize() {
        return size;
    }

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

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

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

我们从删除、增加...操作中，可以发现共同的部分，将其放在一个接口中，然后定义这些操作的类时直接实现这个接口~

IOperation

注意：接口中的方法是抽象方法~

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

AddOperation

添加书籍之后设置书籍列表的长度+1

import java.util.Scanner;

public class AddOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("添加书籍！");
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入新增书籍的名称");
        String name=sc.next();
        System.out.println("请输入新增书籍的作者");
        String author=sc.next();
        System.out.println("请输入新增书籍的价格");
        double price=sc.nextDouble();
        System.out.println("请输入新增书籍的类型");
        String type=sc.next();
        Book book=new Book(name,author,price,type);
        bookList.setSize(bookList.getSize()+1);
        bookList.setBooks(bookList.getSize()-1,book);
        System.out.println("添加书籍成功！");
    }
}

BorrowOperation

通过输入书名借阅，判断这本书是否存在，若不存在，提示不存在；若存在，判断是否可借，可借：借完之后将其借阅状态设置为已借(true)，不可借：提醒不可借~

import java.util.Scanner;

public class BorrowOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("借阅书籍！");
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入您想借阅的书籍名称");
        String name=sc.next();
        int i=0;
        for(;i<bookList.getSize();i++){
            if(bookList.getBooks(i).getName().equals(name)){
                if(bookList.getBooks(i).isBorrowed()==false){
                    System.out.println("借阅成功！");
                    bookList.getBooks(i).setBorrowed(true);
                }else{
                    System.out.println("这本书已被借出啦，看看其他书吧~");
                }
                return;
            }
        }
        if(i>=bookList.getSize()){
            System.out.println("您所借阅的这本书不存在！");
        }
    }
}

DelOperation

注意：删除之后书籍列表长度-1

import java.util.Scanner;

public class DelOperation implements IOperation {
    @Override
    public void work(BookList bookList) {
        //删除书籍相关操作
        System.out.println("删除书籍！");
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入您想删除的书的书名");
        String name=sc.next();
        int i=0;
        for(;i<bookList.getSize();i++){
            if(name.equals(bookList.getBooks(i).getName())){
                if(i==bookList.getSize()-1){
                    bookList.setSize(bookList.getSize()-1);
                }else{
                    bookList.setBooks(i,bookList.getBooks(bookList.getSize()-1));
                    bookList.setSize(bookList.getSize()-1);
                }
                System.out.println("删除书籍成功！");
                break;
            }
        }
        if(i>=bookList.getSize()){
            System.out.println("您所删除的书籍不存在");
        }

    }
}

DisplayOperation

public class DisplayOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        //展示所有书籍信息
        System.out.println("查看所有书籍信息");
        for(int i=0;i<bookList.getSize();i++){
            System.out.println(bookList.getBooks(i));
        }
    }
}

ExitOperation

System.exit();

public class ExitOperation implements IOperation {
    @Override
    public void work(BookList bookList) {
        //退出程序
        System.out.println("退出图书管理系统！byebye~");
        System.exit(0);
    }
}

FindOperation

使用contains()方法~

import java.util.Scanner;

public class FindOperation implements IOperation {
    @Override
    public void work(BookList bookList) {
//        查找书籍相关信息
        System.out.println("查找书籍！");
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入您想查找书籍的名称");
        String name=sc.next();
        int i=0;
        for(;i<bookList.getSize();i++){
            if(bookList.getBooks(i).getName().contains(name)){
                System.out.println(bookList.getBooks(i));
                System.out.println("查找成功！");
                return;
            }
        }
        if(i>=bookList.getSize()){
            System.out.println("您所查找的书籍不存在");
        }
    }
}

ReturnOperation

import java.util.Scanner;

public class ReturnOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        //归还书籍
        System.out.println("归还书籍！");
        System.out.println("请输入要归还书籍的名称");
        Scanner sc=new Scanner(System.in);
        String name=sc.next();
        int i=0;
        for(;i<bookList.getSize();i++){
            if(bookList.getBooks(i).getName().equals(name)){
                bookList.getBooks(i).setBorrowed(true);
                System.out.println("归还成功！");
                return;
            }
        }
        if(i>=bookList.getSize()){
            System.out.println("归还失败！检查一下是否输入有误~");
        }
    }
}

管理员和普通用户中有相同的属性和方法，将其提取出来放到一个类中，创建用户时直接继承这个类即可。

User

abstract public class User {
    protected String name;
    protected IOperation[] operations;
    public abstract int menue();

    public void doOperation(int choice,BookList bookList){
        IOperation operation=this.operations[choice-1];
        operation.work(bookList);
//        operations[choice-1].work(bookList);
    }
}

Admin

import java.util.Scanner;

public class Admin extends User{
    public Admin(String name) {
        this.name = name;
        this.operations=new IOperation[] {
                new FindOperation(),
                new AddOperation(),
                new DelOperation(),
                new DisplayOperation(),
                new ExitOperation()
        };
    }
    @Override
    public int menue() {
        System.out.println("===================");
        System.out.println("欢迎"+name+"进入新一代智能图书管理系统");
        System.out.println("1.查阅书籍信息");
        System.out.println("2.添加新的书籍");
        System.out.println("3.删除书籍");
        System.out.println("4.查看所有书籍列表");
        System.out.println("5.退出系统");
        System.out.println("===================");
        System.out.println("请输入您的选择");
        Scanner sc=new Scanner(System.in);
        int choice=sc.nextInt();
        return choice;
    }
}

NormalUser

import java.util.Scanner;

public class NormalUser extends User{
    public NormalUser(String name) {
        this.name=name;
        this.operations=new IOperation[]{
                new FindOperation(),
                new BorrowOperation(),
                new ReturnOperation(),
                new ExitOperation()
        };
    }
    @Override
    public int menue() {
        System.out.println("===================");
        System.out.println("欢迎"+name+"进入新一代智能图书管理系统");
        System.out.println("1.查阅书籍信息");
        System.out.println("2.借阅书籍");
        System.out.println("3.归还书籍");
        System.out.println("4.退出系统");
        System.out.println("===================");
        System.out.println("请输入您的选择");
        Scanner sc=new Scanner(System.in);
        int choice=sc.nextInt();
        return choice;

    }
}

Main

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        //首先创建一个书籍列表
        BookList bookList=new BookList();
        //用户登录
        User user=login();
        //循环操作
        while(true){
            int choice=user.menue();
            user.doOperation(choice,bookList);
        }
    }

    public static User login(){
        System.out.println("请输入您的姓名");
        Scanner sc= new Scanner(System.in);
        String name=sc.next();
        System.out.println("请选择您的身份：1.管理员 2.普通用户");
        int choice=sc.nextInt();
        if(choice==1){
            return new Admin(name);  //向上转型
        }
        return new NormalUser(name);
    }
}

运行结果