前言

该项目核心需求：

实现简单登录

管理员端实现下列功能

①查找书籍
②增加书籍
③删除书籍
④展示全部书籍
⑤退出系统

通用户实现下列功能

①查询书籍
②借阅书籍
③归还书籍
④退出系统

项目类的设计展示

图书相关的类

Book：定义书籍的信息 BookList：表示书库，里面存放书籍

package book;

/**
 * Created with IntelliJ IDEA
 * Details about unstoppable_t:
 * User: Administrator
 * Date: 2021 -01-19
 * Time: 16:54
 */
public class Book {

    //定义成员变量
    private String name;
    private String author;
    private int price;
    private String type;
    private boolean isBorrowed = false; //表示书的借阅状态

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

    public String getName() {
        return name;
    }

    public String getAuthor() {
        return author;
    }

    public int getPrice() {
        return price;
    }

    public String getType() {
        return type;
    }

    public boolean isBorrowed() {
        return isBorrowed;
    }

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

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

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

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

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

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

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

package book;

/**
 * Created with IntelliJ IDEA
 * Details about unstoppable_t:
 * User: Administrator
 * Date: 2021 -01-19
 * Time: 16:54
 */
public class BookList {

    public int usedSize = 3;  //书架
    public Book[] books = new Book[10]; //书的类型为Book，用顺数组book去存储

    public BookList() {
        books[0] = new Book("三国演义","罗贯中", 100, "小说");
        books[1] = new Book("水浒传", "施耐庵", 100, "小说");
        books[2] = new Book("西游记", "吴承恩", 100, "小说");
    }

    //给指定位置放书
    public void setBooks(int pos,Book book) {
        this.books[pos] = book;
    }

    //拿到指定位置的书
    public Book getBooks(int pos){
        return this.books[pos];
    }

    public int getUsedSize() {
        return usedSize;
    }

    public void setUsedSize(int usedSize) {
        this.usedSize = usedSize;
    }
}

对书库（顺序表）操作的类

//新增
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("请输入书名");
        String name = sc.nextLine();
        System.out.println("请输入书的作者");
        String author = sc.nextLine();
        System.out.println("请输入书的价格");
        int price = sc.nextInt();
        System.out.println("请输入书的类型");
        String type = sc.next();

        Book newBook = new Book(name,author,price,type); //构建新书（对象）
        int size = booklist.getUsedSize(); //通过bookList引用访问当前顺序表长度
        booklist.setBooks(size,newBook); //将新书放在顺序表最后面
        booklist.setUsedSize(size+1); //顺序表放了新书之后，长度加1

    }
}

//借阅
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("请输入书名");
        String name = sc.nextLine();  //name为所要借阅书名

        for (int i = 0; i < booklist.getUsedSize(); i++) {
            //通过booklist下标遍历每一本书
            Book book = booklist.getBooks(i);
            if(book.getName().equals(name)){
                //如果为true，说明要借阅的书存在，我们需要做的是修改书的借阅状态
                book.setBorrowed(true);  //为true表示书已经结出
                return ;
            }
        }
        System.out.println("非常抱歉，本馆没有您要借阅的书！"); //
    }
}

//删除
public class DelOperation implements IOperation{
    @Override
    public void work(BookList booklist) {
        System.out.println("删除书籍");
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入书名");
        String name = sc.nextLine();  //name为所要删除的书名

        int i = 0;
        for (; i < booklist.getUsedSize(); i++) {
            Book book = booklist.getBooks(i);
            if(book.getName().equals(name)){
                break;
            }
        }

        if(i >= booklist.getUsedSize()){
            System.out.println("没有要删除的这本书！");
            return ;
        }

        //此时i为所要删除书的下标
        for (int j = i; j < booklist.getUsedSize()-1; j++) {
            Book book = booklist.getBooks(j+1); //获得j+1位置的书
            booklist.setBooks(j,book);  //将j+1位置的书给j位置
        }
        int size = booklist.getUsedSize();  //获得顺序表长度
        booklist.setUsedSize(size-1);   //删除书后，长度减去1
        System.out.println("书已被删除！");
    }
}

//展示
public class DisplayOperation implements IOperation{
    @Override
    public void work(BookList booklist) {
        System.out.println("展示书籍");

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

//查找
public class FindOperation implements IOperation{
    @Override
    public void work(BookList booklist) {
        System.out.println("查找书籍");
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入书名");
        String name = sc.nextLine();  //name为所要查找书名

        for (int i = 0; i < booklist.getUsedSize(); i++) {
            //通过booklist下标遍历每一本书
            Book book = booklist.getBooks(i);
            if(book.getName().equals(name)){
                System.out.println("该书存在！");
                System.out.println(book);  //直接打印书的信息，toString方法已被重写
                return ;
            }
        }
        System.out.println("没有这本书！");
    }
}

//归还
public class ReturnOperation implements IOperation{
    @Override
    public void work(BookList booklist) {
        System.out.println("归还书籍");
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入书名");
        String name = sc.nextLine();  //name为所要归还的书名

        for (int i = 0; i < booklist.getUsedSize(); i++) {
            Book book = booklist.getBooks(i);
            if(book.getName().equals(name)){
                book.setBorrowed(false);
                System.out.println(book);  //直接打印书的信息，toString方法已被重写
                return ;
            }
        }
        System.out.println("没有你要归还的这本书！");
    }
}

//退出
public class ExitOperation implements IOperation{
    @Override
    public void work(BookList booklist) {
        System.out.println("退出系统");

        System.exit(1); //表示退出系统
    }
}

//总接口
public interface IOperation {
    void work(BookList booklist);
}

用户相关类

用户类

package user;

import book.BookList;
import operation.IOperation;

/**
 * Created with IntelliJ IDEA
 * Details about unstoppable_t:
 * User: Administrator
 * Date: 2021 -01-19
 * Time: 16:55
 */
abstract public class User {

    public String name;
    public IOperation[] operations;

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

    /*
    新建menu方法，理解为用户菜单
    因为SpecialPerson和OrdinaryPerson继承了User，所以让两个子类重写menu方法，二者的菜单展示不一致
    此时menu可以没有具体实现，因而将它设计为抽象方法，因此User类成为抽象类

     */
    abstract public int menu();

    //operations中存放的是哪些操作方法，得看子类
    public void doOperation(int choice, BookList bookList){
        this.operations[choice].work(bookList);
    }
}

管理员

package user;
import operation.*;

import java.util.Scanner;
/**
 * Created with IntelliJ IDEA
 * Details about unstoppable_t:
 * User: Administrator
 * Date: 2021 -01-19
 * Time: 16:56
 * 管理员
 */
public class SpecialPerson extends User{

    //构造方法
    public SpecialPerson(String name){
        super(name);
        this.operations = new IOperation[]{
        new ExitOperation(), //0退出系统
        new FindOperation(),
        new AddOperation(),
        new DelOperation(),
        new DisplayOperation()
        };
    }

    /*
    重写父类User的menu方法
    menu作用：返回你要执行的操作
     */
    @Override
    public int menu() {
        System.out.println("管理员菜单！");

        System.out.println("=================================");
        System.out.println("hello " + this.name + " 热诚欢迎使用本校图书馆管理系统！");
        System.out.println("1.查找图书");
        System.out.println("2.新增图书");
        System.out.println("3.删除图书");
        System.out.println("4.显示所有图书");
        System.out.println("0.退出系统");
        System.out.println("================================");
        System.out.println("请按照提示选择相应操作: ");
        Scanner sc = new Scanner(System.in);
        int choice = sc.nextInt();
        return choice;

    }
}

普通用户

package user;

import operation.*;

import java.util.Scanner;

/**
 * Created with IntelliJ IDEA
 * Details about unstoppable_t:
 * User: Administrator
 * Date: 2021 -01-19
 * Time: 16:57
 * 普通用户
 */
public class OrdinaryPerson extends User{

    //构造方法
    public OrdinaryPerson(String name){
        super(name);

        this.operations = new IOperation[]{
                new ExitOperation(), //0退出系统
                new FindOperation(),
                new BorrowOperation(),
                new ReturnOperation()
        };
    }

    //重写父类User的menu方法
    @Override
    public int menu() {
        System.out.println("普通用户菜单！");

        System.out.println("=================================");
        System.out.println("hello" + this.name + "热诚欢迎使用本校图书馆管理系统！");
        System.out.println("1.查找图书");
        System.out.println("2.借阅图书");
        System.out.println("3.归还图书");
        System.out.println("0.退出系统");
        System.out.println("================================");
        System.out.println("请按照提示选择相应操作: ");
        Scanner sc = new Scanner(System.in);
        int choice = sc.nextInt();
        return choice;
    }
}

主函数程序

import book.BookList;
import user.OrdinaryPerson;
import user.SpecialPerson;
import user.User;

import java.util.Scanner;

/**
 * Created with IntelliJ IDEA
 * Details about unstoppable_t:
 * User: Administrator
 * Date: 2021 -01-19
 * Time: 16:30
 */
public class TrqTest {

    //login（登录）方法返回用户实例，类型为User
    public static User login(){
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入你的姓名: ");
        String name = sc.nextLine();
        System.out.println("请输入你的身份> 1:管理员 0:普通用户");
        int number = sc.nextInt();
        if(number == 1){
            return new SpecialPerson(name);
        }else{
            return new OrdinaryPerson(name);
        }
    }

    public static void main(String[] args) {

        BookList bookList = new BookList();

        //登录
        User user = login(); // 父类引用指向子类实例（向上转型）
        while(true) {
            //user.menu() 调用哪个menu方法，根据登录身份决定
            int choice = user.menu();

            //此doOperation方法是当前user自己的方法
            //choice选择当前用户operations数组中的相应的类，该类产生的对象调用自己的work方法
            user.doOperation(choice, bookList);
        }

    }
}

运行一下看看具体怎么样吧

感谢你看到这里，文章有什么不足还请指正，觉得文章对你有帮助的话记得给我点个赞，每天都会分享java相关技术文章或行业资讯，欢迎大家关注和转发文章！
欢迎关注公众号：前程有光，领取一线大厂Java面试题总结+各知识点学习思维导+一份300页pdf文档的Java核心知识点总结！