基于Java封装继承多态实现的一个简单图书系统

首先我们大概了解下图书系统的需求

1.要有两种身份管理员和普通用户。普通用户和管理员分别对应的功能不一样，需要分开实现

2. 图书系统肯定要有图书，和存放图书的地方，存放就用数组来实现

3.实现对应用户的功能

接下来我们第一步：

首先创建一个book的包，里面存放图书类和存放图书的列表

在图书类中我们要有图书的属性，我们这边简易版只有图书名，作者，类型，价格和图书状态（借出，未被借出）

因为是自己使用，为了安全性使用private修饰，然后构造get，set方法来进行set值和get值，在构造一个toString方法，方便后面来打印，还有一个带参数的构造方法，方便后面进行新建图书

接下来实现存放图书

首先需要创建一个数组来存放书，还需要记录当前书的数量，然后我们可以给数组一个默认的长度，和初始化图书，在初始化时就有几本默认的书，我们需要一个通过下标获取到数组中的书

图书的定义初始化和存放做完后，我们来实现用户

用户分为管理员用户和普通用户，管理员用户和普通用户都是用户，我们就可以定义一个父类User类，然后字类AdminUser和NormalUser来继承父类中共有的方法

父类中定义姓名，然后创建一个User的构造方法，doOperation方法后面会讲到

现在我们要创建我们要实现功能的类，因为每个类都要使用work(BookList bookList)的方法，我们封装一个接口给其他功能类使用

然后逐次创建，继承IOPeration接口，创建完后我们来实现主函数

主函数里要定义一个登陆方法，然后返回用户给系统

因为登陆函数返回了用户，我们主函数调用登陆方法，第一步知道是进入哪个用户，然后通过choice来决定调用的是哪个方法，doOperation这个方法在上面已经实现，传入choice和书的列表，choice则是通过在普通用户类和管理员用户类中的menu()方法，然后输入，通过choice来接收，传给了doOperation方法，根据choice选择对应的方法

接下来我们挨个实现展示图书，查找图书，新增图书，归还图书，借阅图书，退出图书系统，删除图书的各项功能。

展示图书：

查找图书：

新增图书：

借阅图书：

删除图书：

退出系统：

归还图书：

接下来我给完整版代码：

Book类：

package book;/*** @author xiaofan* @version 1.0* @date 2023/11/14 21:49*/
public class Book {private String name;private String author;private String type;private int price;private boolean isBorrowed;@Overridepublic String toString() {return "Book{" +"name='" + name + '\'' +", author='" + author + '\'' +", type='" + type + '\'' +", price=" + price +'\''+((isBorrowed == true) ? "已经借出" : "未被借出")+'}';}public Book(String name, String author, String type, int price) {this.name = name;this.author = author;this.type = type;this.price = price;}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 String getType() {return type;}public void setType(String type) {this.type = type;}public int getPrice() {return price;}public void setPrice(int price) {this.price = price;}public boolean isBorrowed() {return isBorrowed;}public void setBorrowed(boolean borrowed) {isBorrowed = borrowed;}
}

BookList类：

package book;/*** @author xiaofan* @version 1.0* @date 2023/11/14 21:49*/
public class BookList {private Book[] books;  //数组来存放书private int usedSize; //记录当前书架上  实际存放的书的数量//默认容量private static final int DEFAULT_CAPACITY = 10;public BookList(){this.books = new Book[DEFAULT_CAPACITY];//放好书this.books[0] = new Book("三国演义","罗贯中","小说",10);this.books[1] = new Book("西游记","吴承恩","小说",120);this.books[2] = new Book("红楼梦","曹雪芹","小说",110);this.books[3] = new Book("斗破苍穹","天蚕土豆","小说",20);this.usedSize = 4;}public int getUsedSize() {return usedSize;}public void setUsedSize(int usedSize) {this.usedSize = usedSize;}//获取数组某一个下标的书public Book getBook(int pos){
//        if (pos >= 0){
//            return books[pos];
//        } else {
//            System.out.println("下标错误");
//            //return new Exception();
//            //throw new Exception("下标错误"); //抛出异常
//        }return books[pos];}//通过数组的下标的位置来放书public void setBooks(int pos,Book book){books[pos] = book;}public Book[] getBooks() {return books;}
}

User类：

package user;import book.BookList;
import operation.IOPeration;/*** @author xiaofan* @version 1.0* @date 2023/11/14 22:12*/
public abstract class User {protected  String name;//定义一个存放方法的数组protected IOPeration[] ioPerations;public User(String name){this.name = name;}public abstract int menu();//通过传入choice来判断调用的方法public void doOperation(int choice, BookList bookList)  {ioPerations[choice].work(bookList);}
}

AdminUser类：

package user;import operation.*;import java.util.Scanner;/*** @author xiaofan* @version 1.0* @date 2023/11/14 22:14*/
public class AdminUser extends User{public AdminUser(String name) {super(name);this.ioPerations = new IOPeration[]{new ExitOperation(),new FindOperation(),new AddOperation(),new DelOperation(),new ShowOperation()};}public int menu(){System.out.println("******管理员用户*******");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. 显示图书");System.out.println("0. 退出系统");System.out.println("*************");Scanner scanner = new Scanner(System.in);System.out.println("请输入你的操作");int choice = scanner.nextInt();return choice;}
}

NormalUser类：

package user;import operation.*;import java.util.Scanner;/*** @author xiaofan* @version 1.0* @date 2023/11/14 22:14*/
public class NormalUser extends User {public NormalUser(String name) {super(name);this.ioPerations = new IOPeration[]{new ExitOperation(),new FindOperation(),new BorrowOperation(),new ReturnOperation()};}public int menu(){System.out.println("*****普通用户********");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("*************");Scanner scanner = new Scanner(System.in);System.out.println("请输入你的操作");int choice = scanner.nextInt();return choice;}
}

主函数：

import book.BookList;
import user.AdminUser;
import user.NormalUser;
import user.User;import java.util.Scanner;/*** @author xiaofan* @version 1.0* @date 2023/11/14 23:18*/
public class Main {public static User login(){System.out.println("请输入用户名");Scanner scanner = new Scanner(System.in);String name = scanner.nextLine();System.out.println("请输入你的身份： 1 管理员    2 普通用户");int choice = scanner.nextInt();if (choice == 1){//管理员return new AdminUser(name);} else{//普通用户return new NormalUser(name);}}public static void main(String[] args) {BookList bookList = new BookList();//user 指向哪个对象，看返回值是什么？User user = login();while (true){int choice = user.menu();//System.out.println("choice: " + choice);//根据choice的选择来决定调用的是哪个方法user.doOperation(choice,bookList);}}
}

接口

IOPeration：

package operation;import book.BookList;/*** @author xiaofan* @version 1.0* @date 2023/11/14 22:06*/
public interface IOPeration {void work(BookList bookList);
}

功能实现类：

AddOperation：

package operation;import book.Book;
import book.BookList;import java.util.Scanner;/*** @author xiaofan* @version 1.0* @date 2023/11/14 22:02*/
public class AddOperation implements IOPeration{@Overridepublic void work(BookList bookList) {//System.out.println("新增图书！");Scanner scanner = new Scanner(System.in);System.out.println("请输入要添加的书名");String name = scanner.nextLine();System.out.println("请输书名的作者");String author = scanner.nextLine();System.out.println("请输入要添加书的类型");String type = scanner.nextLine();System.out.println("请输入书的价格");int price = scanner.nextInt();Book book = new Book(name,author,type,price);//检查数组当中有没有这本书int currentSize = bookList.getUsedSize();for (int i = 0; i < currentSize; i++) {Book book1 = bookList.getBook(i);if (book1.getName().equals(name)){System.out.println("有相同的书了，不进行存放");return;}}if (currentSize == bookList.getBooks().length){System.out.println("图书已经被放满，不能放了");} else {//将书放在下标的最后一个位置bookList.setBooks(currentSize,book);//将书的数量加1bookList.setUsedSize(currentSize+1);}System.out.println("新增成功");}
}

BorrowOperation：

package operation;import book.Book;
import book.BookList;import java.util.Scanner;/*** @author xiaofan* @version 1.0* @date 2023/11/14 22:04*/
public class BorrowOperation implements IOPeration{@Overridepublic void work(BookList bookList) {//System.out.println("借阅图书！");Scanner scanner = new Scanner(System.in);System.out.println("请输入你要借阅的书名");String name = scanner.nextLine();int curredSize = bookList.getUsedSize();int i = 0;for (; i < curredSize; i++) {Book book = bookList.getBook(i);if (book.getName().equals(name)){if (book.isBorrowed() == false){book.setBorrowed(true);System.out.println("借阅成功");System.out.println(book);return;} else {System.out.println("图书已被借阅，不能再次借出");return;}}}System.out.println("你借阅的图书不存在");}
}

DelOperation：

package operation;import book.Book;
import book.BookList;import java.util.Scanner;/*** @author xiaofan* @version 1.0* @date 2023/11/14 22:02*/
public class DelOperation implements IOPeration {@Overridepublic void work(BookList bookList) {//System.out.println("删除图书！");Scanner scanner = new Scanner(System.in);System.out.println("请输入要删除的书名");String name = scanner.nextLine();int pos = -1;int i = 0;int currentSize = bookList.getUsedSize();for (; i < currentSize; i++) {Book book = bookList.getBook(i);if (book.getName().equals(name)){pos = i;break;}}if (i == currentSize){System.out.println("没有你要删除的图书！");return;}//开始删除int j = pos;for (; j < currentSize-1 ; j++) {Book book = bookList.getBook(j+1);bookList.setBooks(j,book);}//将j置为空bookList.setBooks(j,null);//将书的数量减1bookList.setUsedSize(currentSize-1);System.out.println("删除成功");}
}

ExitOperation：

package operation;import book.BookList;/*** @author xiaofan* @version 1.0* @date 2023/11/14 22:03*/
public class ExitOperation implements IOPeration{@Overridepublic void work(BookList bookList) {System.out.println("退出图书系统！");System.exit(0);}
}

FindOperation：

package operation;import book.Book;
import book.BookList;import java.util.Scanner;/*** @author xiaofan* @version 1.0* @date 2023/11/14 22:02*/
public class FindOperation implements IOPeration{@Overridepublic void work(BookList bookList) {//System.out.println("查找图书！");Scanner scanner = new Scanner(System.in);System.out.println("请输入你要查找的书！");String name = scanner.nextLine();int currentSize = bookList.getUsedSize();for (int i = 0; i < currentSize; i++) {Book book = bookList.getBook(i);if (book.getName().equals(name)){System.out.println("找到了这本书，信息如下");System.out.println(book);return;}}System.out.println("没有找到这本书");}
}

ReturnOperation：

package operation;import book.Book;
import book.BookList;import java.util.Scanner;/*** @author xiaofan* @version 1.0* @date 2023/11/14 22:04*/
public class ReturnOperation implements IOPeration{@Overridepublic void work(BookList bookList) {//System.out.println("归还图书！");Scanner scanner = new Scanner(System.in);System.out.println("请输入你要归还的书名");String name = scanner.nextLine();int curredSize = bookList.getUsedSize();int i = 0;for (; i < curredSize; i++) {Book book = bookList.getBook(i);if (book.getName().equals(name)){if (book.isBorrowed() == true){book.setBorrowed(false);System.out.println("归还成功");System.out.println(book);return;} else {System.out.println("该图书没有被借出，无需归还");return;}}}System.out.println("你归还的图书不存在");}
}

ShowOperation：

package operation;import book.Book;
import book.BookList;/*** @author xiaofan* @version 1.0* @date 2023/11/14 22:03*/
public class ShowOperation implements IOPeration{@Overridepublic void work(BookList bookList) {//System.out.println("展示图书！");int currentSize = bookList.getUsedSize();for (int i = 0; i < currentSize; i++) {Book book = bookList.getBook(i);System.out.println(book);}}
}

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