JavaSE——图书管理

以你之姓@ 2023-10-10 14:45 98阅读 0赞

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> 作者：敲代码の流川枫
> 
> 博客主页：[流川枫的博客][Link 1]
> 
> 专栏：[和我一起学java][java]
> 
> 语录：Stay hungry stay foolish
> 
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**文章目录**

前言

book

Book

BookList

operation

IOperation

AddOperation

BorrowOperation

DelOperation

DisplayOperation

ExitOperation

FindOperation

ReturnOperation

user

User

AdminUser

NormalUser

Main

--------------------

## 前言 ##

> 以面向对象的思想找到并且**抽象出图书管理所需要的对象，再分析这些类和对象应该具有哪些属性和方法，对象通过“属性”和“方法”来分别对应事物所具有的静态属性和动态属性，最后分析类和类之间具体有什么关系，通过各个对象间的交互，**使用对象、类、继承、封装、接口等基本概念完成序设计

抽象出来的对象有：书，书架，用户等，分别建立三个包管理![d39bfba34fe84cbfa2968e6fd7d358c7.png][]

## book ##

### Book ###

package book;
    public class Book {
        //书名
        private String  name;
        //作者
        private String author;
        //价格
        private int price;
        //类型
        private String type;
        //状态
        private boolean isBorrow;
        public Book(String name, String author, int price, String type) {
            this.name = name;
            this.author = author;
            this.price = price;
            this.type = type;
    
        }
        @Override
        public String toString() {
            return "Book{" +
                    "name='" + name + '\'' +
                    ", author='" + author + '\'' +
                    ", price=" + price +
                    ", type='" + type + '\'' +
                    ((isBorrow==true)?"已借出":"未借出")+
                    '}';
        }
        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 isBorrow() {
            return isBorrow;
        }
    
        public void setBorrow(boolean borrow) {
            isBorrow = borrow;
        }
    }

### BookList ###

先存储三本书：

![434bc26a894640b5b69ebdbc61082e57.png][]

package book;
    
    public class BookList {
        private Book[] books = new Book[10];
        private int usedSize;//存储当前书的个数
    
        public BookList() {
    
            books[0] = new Book("三国演义","罗贯中",90,"小说");
            books[1] = new Book("红楼梦","曹雪芹",80,"小说");
            books[2] = new Book("水浒传","施耐庵",70,"小说");
    
            this.usedSize = 3;
        }
    
        public int getUsedSize() {
            return usedSize;
        }
    
        public void setUsedSize(int usedSize) {
            this.usedSize = usedSize;
        }
        public Book getPos(int pos){
            return books[pos];
    
        }
        //存储一本书到指定的位置
        public void setBooks(Book book,int pos){
            books[pos] = book;
        }
    }
    //将对数组的操作写到一个接口中

## operation ##

### IOperation ###

package operation;
    
    import book.BookList;
    
    public interface IOperation {
        void work(BookList bookList);
    }

### AddOperation ###

package operation;
    
    import book.Book;
    import book.BookList;
    
    import java.util.Scanner;
    
    public class AddOperation implements IOperation{
        //添加图书
        public void work(BookList bookList){
            System.out.println("添加图书");
    
            System.out.println("请输入书名");
            Scanner scanner = new Scanner(System.in);
            String name = scanner.nextLine();
            System.out.println("请输入作者");
            String  author = scanner.nextLine();
            System.out.println("请输入价格");
            int price = scanner.nextInt();
            //读取回车
            scanner.nextLine();
            System.out.println("请输入类型");
            String type = scanner.nextLine();
    
            Book book =  new Book(name,author,price,type);
            //获取可以存放的位置
            int currentSize = bookList.getUsedSize();
            //放到指定位置
            bookList.setBooks(book,currentSize);
            //书的个数加一
            bookList.setUsedSize(currentSize+1);
        }
    }

### BorrowOperation ###

package operation;
    
    import book.Book;
    import book.BookList;
    
    import java.util.Scanner;
    
    public class BorrowOperation implements IOperation{
        public void work(BookList bookList){
            System.out.println("借阅图书");
            System.out.println("请输入书名");
            Scanner scanner = new Scanner(System.in);
            String name = scanner.nextLine();
            //遍历是否有要借阅的书并记录下标
            int index = -1;
            int currentSize = bookList.getUsedSize();
            for (int i = 0; i < currentSize ; i++) {
                Book book = bookList.getPos(i);
                if(name.equals(book.getName())){
                    if(book.isBorrow()){
                        System.out.println("已借出");
                    }
                    else{
                        book.setBorrow(true);
                        System.out.println("借阅成功");
                    }
                    return;
                }
            }
            System.out.println("没有要借阅的书");
        }
    }

### DelOperation ###

package operation;
    
    import book.Book;
    import book.BookList;
    
    import java.util.Scanner;
    
    public class DelOperation implements IOperation{
        public void work(BookList bookList){
            System.out.println("删除图书");
            System.out.println("请输入书名");
            Scanner scanner = new Scanner(System.in);
            String name = scanner.nextLine();
    
            //遍历是否有要删除的书并记录下标
            int index = -1;
            int currentSize = bookList.getUsedSize();
            for (int i = 0; i < currentSize ; i++) {
                Book book = bookList.getPos(i);
                if(name.equals(book.getName())){
                    index = i;
                    break;
                }
            }
            if(index == -1){
                System.out.println("没有要删除的书");
                return ;
            }
            for (int i = index; i < currentSize-1 ; i++) {
    
                Book book = bookList.getPos(i+1);
                bookList.setBooks(book,i);
            }
            
            bookList.setBooks(null,currentSize-1);
    
            //重置有效长度
            bookList.setUsedSize(currentSize-1);
            System.out.println("删除成功");
        }
    }

假设有四本书，那么i+1最大值就是3，即 i < currentSize-1才不会越界

![6a46f4bc520042e48e9f03a6948521c6.png][]

删除书之后要置空，否则可能会出现内存泄漏  
一个对象没有人引用才会回收

### DisplayOperation ###

package operation;
    
    import book.Book;
    import book.BookList;
    
    public class DisplayOperation implements IOperation{
        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.getPos(i);
                System.out.println(book);
            }
        }
    }

### ExitOperation ###

package operation;
    
    import book.BookList;
    import com.sun.xml.internal.ws.api.model.wsdl.WSDLOutput;
    
    public class ExitOperation implements IOperation{
        public void work(BookList bookList){
            System.out.println("退出系统");
            System.exit(0);
        }
    }

### FindOperation ###

package operation;
    
    import book.Book;
    import book.BookList;
    
    import java.util.Scanner;
    
    public class FindOperation implements IOperation{
        //查找图书
        public void work(BookList bookList){
            System.out.println("查找图书");
            System.out.println("请输入书名：");
            Scanner scanner = new Scanner(System.in);
            String name = scanner.nextLine();
            int currentSize = bookList.getUsedSize();
            for (int i = 0; i < currentSize ; i++) {
                Book book = bookList.getPos(i);
                if(name.equals(book.getName())){
                    System.out.println(book);
                    return;
                }
            }
            System.out.println("没有这本书");
        }
    }

### ReturnOperation ###

package operation;
    
    import book.Book;
    import book.BookList;
    
    import java.util.Scanner;
    
    public class ReturnOperation implements IOperation{
        public void work(BookList bookList){
    
            System.out.println("归还图书");
            System.out.println("请输入书名");
            Scanner scanner = new Scanner(System.in);
            String name = scanner.nextLine();
    
            int index = -1;
            int currentSize = bookList.getUsedSize();
            for (int i = 0; i < currentSize ; i++) {
                Book book = bookList.getPos(i);
                if(name.equals(book.getName())){
                    book.setBorrow(false);
                    System.out.println("归还成功");
                    return;
                }
            }
            System.out.println("没有要归还的书");
        }
    
    
    }

## user ##

### User ###

package user;
    
    import book.BookList;
    import operation.IOperation;
    
    public abstract class User {
        protected String name;
        //只是定义数组， 没有初始化，内存没有分配
        protected IOperation[] iOperations;
        public User(String name) {
            this.name = name;
        }
        public abstract int menu();
        public void doOperation (int choice, BookList bookList){
            iOperations[choice].work(bookList);
    
        }
    }

### ![ba759ec745b34b5386782e8edc664d7b.png][] ###

需要写一个操作接口数组的方法doOperation()

### AdminUser ###

package user;
    
    import operation.*;
    
    import java.util.Scanner;
    
    //管理员
    public class AdminUser extends User{
        public AdminUser(String name) {
            super(name);
            this.iOperations = new IOperation[]{
                    new ExitOperation(),
                    new FindOperation(),
                    new AddOperation(),
                    new DelOperation(),
                    new DisplayOperation()
    
            };
    
        }
    
        public int menu(){
            System.out.println("*************");
            System.out.println("hello"+name+"欢迎来到图书管理");
            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("*************");
            System.out.println("请输入你的操作：");
    
            Scanner scanner = new Scanner(System.in);
            int choice = scanner.nextInt();
            return choice;
    
        }
    }

### NormalUser ###

package user;
    
    import operation.*;
    
    import java.util.Scanner;
    
    //普通用户
    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("*************");
            System.out.println("hello" + name + "欢迎来到图书管理");
            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("请输入你的操作：");
            Scanner scanner = new Scanner(System.in);
            int choice = scanner.nextInt();
            return choice;
        }
    
    }

## Main ##

import book.BookList;
    import user.AdminUser;
    import user.NormalUser;
    import user.User;
    
    import java.util.Scanner;
    
    public class Main {
        //利用向上转型确定是哪个对象
        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("请输入你的身份：1. 管理员  2. 用户");
            int choice = scanner.nextInt();
            if(choice==1){
               return new AdminUser(userName);
            }
            else{
                return new NormalUser(userName);
            }
        }
    
        public static void main(String[] args) {
            //先放三本书
            BookList bookList = new BookList();
            //登录
            User user =  login();
            while(true){
                int choice = user.menu();
                user.doOperation(choice,bookList);
            }
        }
    }

![22b0971abeb346ccb0105476845f0d91.png][]

当引用的对象不同时，会打印不同的菜单

> **“ 本期的分享就到这里了， 记得给博主一个三连哈，你的支持是我创作的最大动力！**

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[Link 1]: https://blog.csdn.net/chenchenchencl?spm=1011.2421.3001.5343
[java]: https://blog.csdn.net/chenchenchencl/category_11932758.html
[Link 2]: https://www.nowcoder.com/link/pc_csdncpt_qdmdlcf_c
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