✨博客主页: XIN-XIANG荣
✨系列专栏:【Java SE】
✨一句短话: 难在坚持,贵在坚持,成在坚持!

前言

这篇博客是在学习了一部分Java基础语法之后的练习项目，通过这个小项目的练习，对Java中的类和对象，抽象类和接口，面向对象的继承、多态和封装、组合等进行熟悉理解；抽象出不同的对象，将对象进行合理的设计，完成对象之间的交互，面向对象进行编程。

1. 项目需求

图书管理系统，面向管理员和普通用户使用，对管理员的开放的功能有：添加图书，删除图书，查找图书，显示图书和退出程序等；对普通用户的开放的功能有：查找图书，借阅图书，归还图书和退出程序。

2. 实现思路

先抽象提取出不同的对象，首先想到的对象是用户和书，

用户可分为管理员和普通用户，将管理员和普通用户共有的属性设置为一个父类User，管理员和普通用户继承User，可以先将父类设置为普通类，在写码过程如果合适可以修改为抽象类；

系统对书进行管理，书本身就可以抽象为一个对象；对多本书进行操作管理，书架也可以抽象为一个对象；所以书和书架用两个类来实现，书架可以设计为一个数组；

这里系统对书进行管理，其实就是对书架对应数组进行操作，不同的操作可以通过一个标准去实现，也就是可以定义一个接口，每一个操作类去实现这个接口，完成向上转型，通过接口实现多态；

然后写代码的过程中思考完善各个对象的成员，最终实例化对象，通过不同对象之间的交互完成管理系统。

3. 代码实现

包的设计

book包

Book类

package book;

public class Book {
    private String name;//书名
    private String author;//书的作者
    private int price;//书的价格
    private String type;//书的类型
    private boolean borrowed;//是否被借出，默认false

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

    public String getName() {
        return name;
    }

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

    public String getAuthor() {
        return author;
    }

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

    public int getPrice() {
        return price;
    }

    public void setPrice(int price) {
        this.price = price;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public Boolean getBorrowed() {
        return borrowed;
    }

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

    @Override
    public String toString() {
        return "Book{" +
                "name='" + name + '\'' +
                ", author='" + author + '\'' +
                ", price=" + price +
                ", type='" + type + '\'' +
                ", borrowed=" + ((borrowed==true) ? "已借出" : "未借出") +
                '}';
    }
}

BookList类

package book;

public class BookList {
    private Book[] books = new Book[100];
    private int usedsize;
    //书架当中默认有三本书

    public BookList() {
        this.books[0] = new Book("三国演义","罗贯中",66,"小说");
        this.books[1] = new Book("西游记","吴承恩",68,"小说");
        this.books[2] = new Book("红楼梦","曹雪芹",64,"小说");
        this.usedsize = 3;
    }

    public int getUsedsize() {
        return usedsize;
    }

    public void setUsedsize(int usedsize) {
        this.usedsize = usedsize;
    }


    public Book getBooks(int pos){
        return this.books[pos];
    }

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

operations包

IOperation接口

package operations;

import book.BookList;

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

AddOperation类

package operations;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class AddOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("新增图书");
        //输入图书信息
        System.out.println("输入新增图书名称:");
        Scanner scanner = new Scanner(System.in);
        String name = scanner.nextLine();
        System.out.println("输入新增图书作者:");
        String author = scanner.nextLine();
        System.out.println("输入新增图书价格:");
        int price = scanner.nextInt();
        scanner.nextLine();
        System.out.println("输入新增图书类型:");
        String type = scanner.nextLine();

        Book book = new Book(name, author, price, type);
        //获取存书位置
        int currentSize = bookList.getUsedsize();
        //把书放到书架（数组）
        bookList.setBooks(book, currentSize);
        //书的总数加1
        bookList.setUsedsize(currentSize+1);
        System.out.println("添加成功！");
    }
}

BorrowOperation类

package operations;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class BorrowOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("借阅图书");
        System.out.println("输入要借阅图书的名称:");
        Scanner scanner = new Scanner(System.in);
        String name = scanner.nextLine();
        int currentSize = bookList.getUsedsize();

        for (int i = 0; i < currentSize; i++) {
            Book book = bookList.getBooks(i);
            if (name.equals(book.getName())){
                if(book.getBorrowed()){
                    System.out.println("该书已经被借出！");
                    return;
                }else {
                    book.setBorrowed(true);
                    System.out.println("借阅成功！");
                    return;
                }
            }
        }
        System.out.println("没有找到你要借阅的书");
    }
}

DelOperation类

package operations;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class DelOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("删除图书");
        System.out.println("输入要删除图书的名称:");
        Scanner scanner = new Scanner(System.in);
        String name = scanner.nextLine();
        int currentSize = bookList.getUsedsize();

        //找到并记录要删除书的下标
        int index = -1;
        for (int i = 0; i < currentSize; i++) {
            Book book = bookList.getBooks(i);
            if (name.equals(book.getName())){
                index = i;
                break;
            }
        }
        if(-1 == index) {
            System.out.println("没有找到要删除的这本书！");
        }else {
            for (int i = index; i < currentSize-1; i++) {
                Book book = bookList.getBooks(i+1);
                bookList.setBooks(book, i);
            }
            //每次删除，都要将原来最后一本书位置的引用置空
            bookList.setBooks(null,currentSize-1);
            bookList.setUsedsize(currentSize-1);
            System.out.println("删除成功");
        }
    }
}

DisplayOperation类

package operations;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class DisplayOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("显示图书");
        int currentSize = bookList.getUsedsize();

        for (int i = 0; i < currentSize; i++) {
            Book book = bookList.getBooks(i);
            System.out.println(book);
        }
    }
}

ExitOperation类

package operations;

import book.BookList;

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

FindOperation类

import book.Book;
import book.BookList;

import java.util.Scanner;

public class FindOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("查找图书");
        System.out.println("输入要查找图书的名称:");
        Scanner scanner = new Scanner(System.in);
        String name = scanner.nextLine();
        int currentSize = bookList.getUsedsize();

        for (int i = 0; i < currentSize; i++) {
            Book book = bookList.getBooks(i);
            if (name.equals(book.getName())){
                System.out.println("找到了，该书信息如下:");
                System.out.println(book);
                return;
            }
        }
        System.out.println("没有找到这本书！");
    }
}

ReturnOperation类

package operations;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class ReturnOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("归还图书");
        System.out.println("输入要归还图书的名称:");
        Scanner scanner = new Scanner(System.in);
        String name = scanner.nextLine();
        int currentSize = bookList.getUsedsize();

        for (int i = 0; i < currentSize; i++) {
            Book book = bookList.getBooks(i);
            if (name.equals(book.getName())){
                if(book.getBorrowed()){
                    book.setBorrowed(false);
                    System.out.println("归还成功！");
                    return;

                }else {
                    System.out.println("该书未借出！");
                    return;
                }
            }
        }
        System.out.println("没有找到你要归还的书");
    }
}

user包

User类

public abstract class User {
    protected String name;
    protected IOperation[] iOperation;

    public User(String name) {
        this.name = name;
    }
    public abstract int menu();
    public void doOperation(int choice, BookList bookList){
        iOperation[choice].work(bookList);
    }
}

AdminUser类

package user;

import operations.*;

import java.util.Scanner;

public class AdminUser extends User{
    public AdminUser(String name) {
        super(name);
        this.iOperation = new IOperation[]{
                new ExitOperation(),
                new FindOperation(),
                new AddOperation(),
                new DelOperation(),
                new DisplayOperation()
        };
    }

    @Override
    public int menu() {
        System.out.println("---------------------------------");
        System.out.println("Hello 管理员:>"+""+name+" 欢迎来到图书管理系统！");
        System.out.println("      1.查找图书  2.新增图书");
        System.out.println("      3.删除图书  4.显示图书");
        System.out.println("           0.退出系统");
        System.out.println("---------------------------------");
        System.out.println("请输入你的操作:");
        Scanner scanner = new Scanner(System.in);
        int choice = scanner.nextInt();
        return choice;
    }
}

NormalUser类

package user;

import operations.*;

import java.util.Scanner;

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

    @Override
    public int menu() {
        System.out.println("---------------------------------");
        System.out.println("Hello 用户:>"+name+" 欢迎来到图书管理系统！");
        System.out.println("      1.查找图书  2.借阅图书");
        System.out.println("      3.归还图书  0.退出系统");
        System.out.println("---------------------------------");
        System.out.println("请输入你的操作:");
        Scanner scanner = new Scanner(System.in);
        int choice = scanner.nextInt();
        return choice;
    }
}

Main类

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

import java.util.Scanner;

public class Main {
    public static User login(){
        System.out.println("请输入你的姓名:");
        Scanner scanner = new Scanner(System.in);
        String userName = scanner.nextLine();
        System.out.println("请确认你的身份:> |1->管理员|0->普通用户|");
        int choice = scanner.nextInt();
        if(1==choice){
            return new AdminUser(userName);
        }else{
            return new NormalUser(userName);
        }
    }

    public static void main(String[] args) {
        //准备数据
        BookList bookList = new BookList();
        //登录
        User user = login();

        while (true) {
            int choice = user.menu();
            user.doOperation(choice, bookList);
        }
    }
}

4. 实现效果

管理员

普通用户