图书管理系统是对抽象类、接口、继承、封装等知识点的应用，也是对学习的知识的总结。

对于这个图书管理系统我们大致分为三个步骤进行编写。

（源码我放在最后）

一、对于图书相关类的创建和使用。

我们先先创建一个包book

1.1在包中我们先创建Book类来表示一本书

package book;

public class Book {
    private String name;
    private String author;
    private int price;
    private String type;
    private boolean isBorrowed =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 isBorrowed() {return isBorrowed;}
    public void setBorrowed(boolean borrowed) {isBorrowed = borrowed;}

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

在这个类当中由于我们对于一本书中的类容进行了编写，由于为都为私有，我们设置了它的get和set方法，同时我们也重写了toString方法，这样一本书就编写好了。

1.2创建BookList类用来保存N本书

package book;

public class BookList {
    private Book[] books=new Book[10];
    private int size=0;
    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");
        this.size=3;
    }

    public Book[] getBooks() {return books;}
    public void setBooks(Book[] books) {this.books = books;}
    public int getSize() {return size;}
    public void setSize(int size) {this.size = size;}
}

在初始化的时候我们定义三本书放进去，并将它4们的get和set方法设置出来。

二、创建操作相关的类

我们将相关类都放在operation包中

我们先创建一个接口

package operation;

import book.BookList;

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

我们在接口中添加了一个方法，去遍历很多本书，通过继承让其他类继承这个接口，从而实现work方法。

public class AddOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        
    }
}

public class DelOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        
    }
}

public class FindOperation implements IOperation{
    @Override
    public void work(BookList bookList) {

    }
}

public class RemoveOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        
    }
}

public class DisplayOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        
    }
}

public class BorrowOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        
    }
}

public class ReturnOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        
    }
}

public class ExitOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        
    }
}

我们创建了不同的方法通过调用接口来实现方法。

三、创建用户相关的类

创建一个user包

package uesr;

import operation.IOperation;

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

    //显示菜单
    abstract public int menu();
}

创建普通用户类

package uesr;

import operation.*;

import java.util.Scanner;

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

    @Override
    public int menu() {
        System.out.println("=============");
        System.out.println("欢迎用户使用图书系统");
        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("输入你的选择");
        Scanner scanner=new Scanner(System.in);
        int choice=scanner.nextInt();
        return choice;
    }
}

创建管理员类

package uesr;

import operation.*;

import java.util.Scanner;

public class AdminUser extends User{
    public AdminUser(String name){
        this.name=name;
        this.operations=new IOperation[]{
                new ExitOperation(),
                new FindOperation(),
                new AddOperation(),
                new DelOperation(),
                new DisplayOperation()
        };
    }
    @Override
    public int menu() {
        System.out.println("=============");
        System.out.println("欢迎管理员使用图书系统");
        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("输入你的选择");
        Scanner scanner=new Scanner(System.in);
        int choice=scanner.nextInt();
        return choice;
    }
}

四、对类进行整合（编写主函数）

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

import java.util.Scanner;

public class Main {
    public static User login(){
        Scanner scanner=new Scanner(System.in);
        System.out.println("请输入姓名");
        String name=scanner.next();
        System.out.println("请输入你的身份(1、管理员 2、普通用户)");
        int who=scanner.nextInt();
        if(who==1){
            return new AdminUser(name);
        }else{
            return new NormalUser(name);
        }
    }

    public static void main(String[] args) {
        BookList bookList=new BookList();

        User user=login();

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

对于主函数的整合，我们想要将他们结合起来我们要在User中添加doOperation方法：

    public void doOperation(int choice, BookList bookList){
        this.operations[choice].work(bookList);
    }

通过调用方法来进行对于类的整合。

最后我们加入while循环使代码循环起来

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

实现：

五、对于操着相关类的实现

5.1 AddOperation(添加)实现类

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class AddOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("新曾图书！");
        Scanner scanner=new Scanner(System.in);
        System.out.println("请输入书的名称:");
        String name=scanner.nextLine();
        System.out.println("请输入书的作者:");
        String author=scanner.nextLine();
        System.out.println("请输入书的类型:");
        String type=scanner.nextLine();
        System.out.println("请输入书的价格:");
        int price=scanner.nextInt();

        Book book=new Book(name,author,price,type);
        int size=bookList.getSize();
        for (int i = 0; i < size; i++) {
            Book book1=bookList.getBook(i);
            if(book.getName().equals(book1.getName())){
                System.out.println("书名已经重复");
                return;
            }
        }

        bookList.setBook(size,book);
        bookList.setSize(size+1);
        System.out.println("新增图书成功！！！！");

    }
}

在使用时我们要在BookList中加入两个方法

    public Book getBook(int size){
        return books[size];
    }
    public void setBook(int pos,Book book){
        books[pos]=book;
    }

5.2 DisplayOperation(打印)类的实现

public class DisplayOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        int size=bookList.getSize();
        for (int i = 0; i < size; i++) {
            Book book1=bookList.getBook(i);
            System.out.println(book1);
        }
    }
}

要注意：不能直接写System.out.println(bookList[i]);

5.3 FindOperation(查找)类的实现

public class FindOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("查找图书！！");
        System.out.println("请输入图书的名称：");
        Scanner scanner=new Scanner(System.in);
        String name=scanner.nextLine();
        int size=bookList.getSize();
        for (int i = 0; i < size; i++) {
            Book book1=bookList.getBook(i);
            if(book1.getName().equals(name)){
                System.out.println("找到了!!!");
                System.out.println(book1);
                return;
            }
        }
        System.out.println("没有找到！！！");
    }
}

5.4 ExitOperation(退出)类的实现

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

5.5 DelOperation(删除)类的实现

public class DelOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("删除图书！！");
        System.out.println("请输入删除图书的名称：");
        Scanner scanner=new Scanner(System.in);
        String name=scanner.nextLine();
        int size=bookList.getSize();
        int pos=-1;
        for (int i = 0; i < size; i++) {
            Book book1=bookList.getBook(i);
            if(book1.getName().equals(name)){
                pos=i;
                break;
            }
        }
        if(pos!=-1){
            for (int i = pos; i <size-1 ; i++) {
                Book book=bookList.getBook(i+1);
                bookList.setBook(i,book);
            }
            bookList.setSize(size-1);
            System.out.println("删除成功！！！");
            return;
        }
        System.out.println("删除失败！！！！");
    }
}

5.6 BorrowOperation(借阅)类的实现

public class BorrowOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("借阅图书！！");
        System.out.println("请输入借阅图书的名称：");
        Scanner scanner=new Scanner(System.in);
        String name=scanner.nextLine();
        int size=bookList.getSize();
        for (int i = 0; i < size; i++) {
            Book book1=bookList.getBook(i);
            if(book1.getName().equals(name)){
                book1.setBorrowed(true);
                System.out.println("借阅成功！！！！");
                return;
            }
        }
        System.out.println("借阅失败！！！");
    }
}

5.7 ReturnOperation(归还)类的实现

public class RemoveOperation implements IOperation{
    @Override
    public void work(BookList bookList) {
        System.out.println("归还图书！！");
        System.out.println("请输入归还图书的名称：");
        Scanner scanner=new Scanner(System.in);
        String name=scanner.nextLine();
        int size=bookList.getSize();
        for (int i = 0; i < size; i++) {
            Book book1=bookList.getBook(i);
            if(book1.getName().equals(name)){
                book1.setBorrowed(false);
                System.out.println("归还成功！！！！");
                return;
            }
        }
        System.out.println("归还失败！！！");
    }
}

这样简单的图书管理系统就做完成了，下面是代码：图书管理系统。