JAVA实现——简易图书馆系统

图书馆系统

图书馆系统:需要分为管理员和普通用户的操作
需要以下包以及类
在这里插入图片描述

代码及注释如下

一、book包下

1.Book类

package book;

public class Book {
    private String name;//书名
    private String author;//作者
    private int price;//价格
    private String type;//书的类型
    private boolean isBorrowed;//是否被借出

//构造方法

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

    //被private,提供方法
    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 isBorrowed() {
        return isBorrowed;
    }
    public void setBorrowed(boolean borrowed) {
        isBorrowed = borrowed;
    }
    //重写toString
    @Override
    public String toString() {
        return "BookList{" +
                "name='" + name + '\'' +
                ", author='" + author + '\'' +
                ", price=" + price +
                ", type='" + type + '\'' +
                ((isBorrowed == true)?"已借出":"未借出")+
                //", isBorrowed=" + isBorrowed +
                '}';
    }
}

2.BookList类

package book;

public class BookList {
//封装
    private Book[] books;
    private int usedSize;//记录当前书架存放几本书
//不带参数的构造方法
    public BookList(){
        this.books = new Book[10];//分配内存 初始化

        this.books[0] = new Book("三国演义","罗贯中",49,"小说");
        this.books[1] = new Book("西游记","吴承恩",45,"小说");
        this.books[2] = new Book("水浒传","施耐庵",50,"小说");
        this.usedSize = 3;
    }
//
    public int getUsedSize() {
        return usedSize;
    }

    public void setUsedSize(int usedSize) {
        this.usedSize = usedSize;
    }
    public Book getBook(int pos){
        return books[pos];
    }
    public void setBook(Book book,int pos){
        books[pos] = book;
    }
}

二、operation包下

1.IOPeration接口

package operation;
import book.BookList;
//接口,不能有具体的实现
public interface IOPeration {
    void work(BookList bookList);

}

2.AddOperation类

package operation;
import book.Book;
import book.BookList;

import java.util.Scanner;

public class AddOperation implements IOPeration {
    //重写
    @Override
    public void work(BookList bookList) {
        System.out.println("新增图书!");
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入您要新增图书的书名:");
        String name = scanner.nextLine();
        System.out.println("请输入您要新增图书的作者:");
        String autor = scanner.nextLine();
        System.out.println("请输入您要新增图书的价格:");
        int price = scanner.nextInt();//在Int在Line前面时,nextLine会吃回车
        System.out.println("请输入您要新增图书的类型:");
        //String type = scanner.nextLine();
        String type = scanner.next();//读不了空格
        /*吃回车解决方案:
        1.去掉Line:
        int price = scanner.nextInt();
        String type = scanner.next();//读不了空格
        2.换位:
        String type = scanner.nextLine();
        int price = scanner.nextInt();
        3.多读一次,把回车空格吃掉:
        int price = scanner.nextInt();
        scanner.nextLine();//多读一次
        String type = scanner.nextLine();
        */

        //构造一个书的对象
        Book book = new Book(name, autor, price, type);
        int currentSize = bookList.getUsedSize();

        for (int i = 0; i < currentSize; i++) {
            Book tmp = bookList.getBook(i);
            //找书
            if (tmp.getName().equals(name)) {
                System.out.println("本书存在,不能重复添加!");
                return;
            }
        }
        //没有重复的书,开始新增
        bookList.setBook(book,currentSize);
        bookList.setUsedSize((currentSize + 1));
    }
}

3.BorrowPeration类

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class BorrowPeration implements IOPeration{
    //重写
    @Override
    public void work(BookList bookList) {
        System.out.println("借阅图书!");
        System.out.println("请输入你要借阅的图书的书名");
        Scanner scanner = new Scanner(System.in);
        String name = scanner.nextLine();
        int currentSize = bookList.getUsedSize();
        for (int i = 0; i < currentSize; i++) {
            Book book = bookList.getBook(i);

            if(book.getName().equals(name)){
                book.setBorrowed(true);
                System.out.println("借阅成功!");
                return;
            }
        }
        System.out.println("没有你要借阅的书:"+name);
    }
}

4.DelOperation类

package operation;
import book.Book;
import book.BookList;

import java.util.Scanner;

public class DelOperation implements IOPeration{
    //重写
    @Override
    public void work(BookList bookList) {
        System.out.println("删除图书!");
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入您要删除图书的书名:");
        int currentSize = bookList.getUsedSize();
        String name = scanner.nextLine();
        //判断是否有删除的条件
        int index = -1;//数组没有-1下标
        int i = 0;
        for ( ;i < currentSize; i++) {
            Book tmp = bookList.getBook(i);
            //找书
            if (tmp.getName().equals(name)) {
                index = i;
                break;//已记录
            }
        }
        if(i >= currentSize){
            System.out.println("没有您要删除的图书!");
            return;
        }
        //可删除
        for (int j = index; j < currentSize-1; j++) {
            //bookList[j] = bookList[j+1,但bookList不是个数组
            //利用setbook,将后一个覆盖前一个
            Book book = bookList.getBook(j+1);
            bookList.setBook(book,j);
        }
        //此时两个书,指向同一个对象,需要防止对象的泄露
        bookList.setBook(null,currentSize - 1);
        //防止泄露:删除后置为空
        bookList.setUsedSize(currentSize - 1);
        System.out.println("删除成功!");
    }
}

5.ExitOperation类

package operation;

import book.BookList;

public class ExitOperation implements IOPeration{
    //重写
    @Override
    public void work(BookList bookList) {
        System.out.println("退出系统!");
        //退出后需要手动回收 bookList 资源
        System.exit(0);
    }
}

6.FindOperation类

package operation;
import book.Book;
import book.BookList;

import java.util.Scanner;

public class FindOperation implements IOPeration{
    //重写
    @Override
    public void work(BookList bookList) {
        System.out.println("查找图书!");
        System.out.println("请输入你要查找的图书的书名");

        Scanner scanner = new Scanner(System.in);
        String name = scanner.nextLine();
        int currentSize = bookList.getUsedSize();
        for (int i = 0; i < currentSize; i++) {
            /*Book book = bookList[i];若不写一个public
             此时的Book[]数组被,private修饰,无法调用。
             所以不能用此方法*/
            Book book = bookList.getBook(i);
            //找书
            if(book.getName().equals(name)){
                System.out.println("本书存在,信息如下:");
                System.out.println(book);
                return;
            }
        }
        //没找到
        System.out.println("没找到本书,书名为:"+name);
    }
}

7.ReturnOperation类

package operation;
import book.Book;
import book.BookList;

import java.util.Scanner;

public class ReturnOperation implements IOPeration{
    //重写
    @Override
    public void work(BookList bookList) {
        System.out.println("归还图书!");
        System.out.println("请输入你要归还的图书的书名:");
        Scanner scanner = new Scanner(System.in);
        String name = scanner.nextLine();
        int currentSize = bookList.getUsedSize();
        for (int i = 0; i < currentSize; i++) {
            Book book = bookList.getBook(i);

            if(book.getName().equals(name)){
                book.setBorrowed(false);
                System.out.println("归还成功!");
                return;
            }
        }
        System.out.println("没有你要归还的书:"+name);
    }
}

8.ShowOperation类

package operation;
import book.Book;
import book.BookList;
public class ShowOperation implements IOPeration{
    //重写
    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.getBook(i);
            System.out.println(book);
        }
    }
}

三、user包下

1.AdminUser类

package user;

import operation.*;

import java.util.Scanner;

//继承
public class AdminUser extends User{
//构造方法
    public AdminUser(String name) {
        super(name);
        //数组初始化,对应下标引用方法
        this.ioPerations = new IOPeration[]{
                new ExitOperation(),
                new FindOperation(),
                new AddOperation(),
                new DelOperation(),
                new ShowOperation()
        };
    }
    public int menu(){
        System.out.println("*********管理员菜单*********");
        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);
        int choice = scanner.nextInt();
        return choice;//返回给Main
    }
}

2.NormalUser类

package user;

import operation.*;

import java.util.Scanner;

//继承
public class NormalUser extends User{//继承了User属性
    public NormalUser(String name) {
        super(name);
        //数组初始化,对应下标引用方法
        this.ioPerations = new IOPeration[]{
                new ExitOperation(),
                new FindOperation(),
                new BorrowPeration(),
                new ReturnOperation()

        };
        //不知道给数组赋值多大,请这样使用
        //this.ioPerations = {};报错,只有在定义的时候才能这样赋值
    }
    public int menu(){
        System.out.println("*********普通用户菜单*********");
        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);
        int choice = scanner.nextInt();
        return choice;//返回给Main
    }
}

3.User类

package user;

import book.BookList;
import operation.IOPeration;

//抽象类
public abstract class User {
    protected String name;
//定义数组
    protected IOPeration[] ioPerations;//未初始化
    //数组未被分配空间时,数组的初始值为null,只有被分配空间后才能视为初始化

//构造方法
    public User(String name) {
        this.name = name;
    }
    //在User内定义的menu方法时,我们发现menu没有具体实现
    //则没有具体的实现所有定义为 抽象方法,抽象方法由 抽象类 修饰
    public abstract int menu();

//选择引用对象
    public void doOperation(int choice, BookList bookList){
        //非静态方法,调用时需要对象的引用
        //this.ioPerations是会调用operation包内的类
        this.ioPerations[choice].work(bookList);
    }
}

四、Main

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 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();
        //向上转型
        if(choice == 1){
            return new AdminUser(name);
        }else{
            return new NormalUser(name);
        }
    }
    public static void main(String[] args) {
        BookList bookList = new BookList();
        //此时user的指向未知(两种),向上转型
        User user = login();
        while(true){
            int choice = user.menu();
       /*通过父类引用menu,
       但此时User中没有menu方法,
       所以要定义一个menu方法,
       */
        /* 发生动态绑定
        根据菜单返回的choice来执行对应操作,
        此时有多个menu方法,则发生了 多态,
        (引用的对象不一样,调用同一个方法所展示的行为是不一样的)
        */
            user.doOperation(choice,bookList);
        }
    }
}

————————————————
完…
敬请不吝赐教!

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