分层情况

实体类Book代码 

//实体类
public class Book {
    private int id;
    private String name;
    private int bsum;

    public Book() {
    }

    public Book(int id, String name, int bsum) {
        this.id = id;
        this.name = name;
        this.bsum = bsum;
    }

    public int getId() {
        return id;
    }


    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public int getBsum() {
        return bsum;
    }

    public void setBsum(int bsum) {
        this.bsum = bsum;
    }

    @Override
    public String toString() {
        return "Book{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", bsum=" + bsum +
                '}';
    }
}

控制层BookController代码

import com.xszx.beans.Book;
import com.xszx.service.BookService;
import com.xszx.service.impl.BookServiceImpl;

import java.util.List;
import java.util.Scanner;

//控制层  控制请求转发
public class BookController {
    Scanner sc=new Scanner(System.in);

    BookService bookService = new BookServiceImpl();

    //主方法
    public void menu(){
        System.out.println();
        System.out.println("                     ---小张图书管理系统---                          ");
        System.out.println("***【1】查看图书列表 【2】添加图书 【3】修改图书 【4】删除图书 【0】退出系统***");
        System.out.println("请选择您要进行的操作：");
        int n = sc.nextInt();
        if(n==1){
            checkBook();
            menu();
        }else if (n==2){
            addBook();
            menu();
        }else if(n==3){
            alterBook();
            menu();
        }else if (n==4){
            deleteBook();
            menu();
        }else if(n==0){
            System.out.println("系统已退出，欢迎下次使用！！！");
            System.exit(0);
        }
    }
    //删除图书
    private void deleteBook() {
        Book book = new Book();
        System.out.println("请输入您要删除的图书名称:");
        book.setName(sc.next());
        //判断名字是否存在 存在则删除 不存在则提示不存在
        boolean b=bookService.getbookname(book);
        if(b){
            bookService.deleteBook(book);
            System.out.println("删除成功！");
        } else{
            System.out.println("您要删除的图书不存在！");
            menu();
        }
    }
    //修改图书
    private void alterBook() {
        Book book = new Book();
        System.out.println("请输入您要修改的图书名称:");
        book.setName(sc.next());
        //判断名字是否存在 存在则继续修改 不存在则提示不存在

        boolean b=bookService.getbookname(book);
        if(b){
            Book book1 = new Book();
            System.out.println("请输入修改后的图书名称:");
            book1.setName(sc.next());
            System.out.println("请输入修改后的图书库存:");
            book1.setBsum(sc.nextInt());
            bookService.alterBook(book,book1);
            System.out.println("修改成功！");
        } else{
            System.out.println("您要修改的图书不存在！");
            menu();
        }
    }
    //增加图书
    private void addBook() {
        Book book = new Book();
        System.out.println("请输入您要添加的图书名称:");
        book.setName(sc.next());
        //判断名字是否存在 存在则提示名字冲突 不存在则继续执行

        boolean b=bookService.getbookname(book);
        if(b){
            System.out.println("添加的图书名字冲突");
            menu();
        }else{
            System.out.println("请输入您要添加的图书库存:");
            book.setBsum(sc.nextInt());


            //后台添加完成，是否成功

            int i = bookService.addbook(book);
            if (i==1){
                System.out.println("添加成功！！！");
                menu();
            }else{
                System.out.println("添加失败！！！");
                menu();
            }
        }

    }

    //查看图书
    private void checkBook() {
        List<Book> list = bookService.getbook();
        for (Book book : list){
            System.out.println(book);
        }
        menu();
    }
}

数据层BookDao代码

import com.xszx.beans.Book;

import java.util.ArrayList;
import java.util.List;

//数据层   连接数据库  处理数据  写sql   后期为接口
public class BookDao {
    static List<Book> blist=new ArrayList<>();
    static{
        blist.add(new Book(1,"三国",666));
        blist.add(new Book(2,"水浒",888));
        blist.add(new Book(3,"红楼梦",999));
        blist.add(new Book(4,"西游记",222));
        blist.add(new Book(5,"宝莲灯",333));
    }

    public List<Book> getbooks() {
        return blist;
    }

    public int addbook(Book book) {
        int id = blist.get(0).getId();
        //查找最大值
        for (Book bk : blist){
            if (id<bk.getId()){
                id=bk.getId();
            }
        }
        book.setId(id+1);
        blist.add(book);
        return 1;

    }
    //判断名字是否存在
    public boolean getbookname(Book book) {
       for (Book bk : blist){
           if(bk.getName().equals(book.getName())){
               return true;
           }
       }
       return false;
    }

    public void alterBook(Book book, Book book1) {
        for (Book bk : blist){
            //修改参数
            if(bk.getName().equals(book.getName())){
                bk.setName(book1.getName());
                bk.setBsum(book1.getBsum());
            }
        }
    }

    public void deleteBook(Book book) {
        for (Book bk : blist){
            //删除元素
            if(bk.getName().equals(book.getName())){
                blist.remove(bk);
                break;
            }
        }
    }
}

 业务层接口BookService代码

import com.xszx.beans.Book;

import java.util.List;

//业务层  处理业务
public interface BookService {
    List<Book> getbook();

    int addbook(Book book);

    boolean getbookname(Book book);

    void alterBook(Book book, Book book1);

    void deleteBook(Book book);
}

 业务层实现类BookServiceImpl代码

import com.xszx.beans.Book;
import com.xszx.dao.BookDao;
import com.xszx.service.BookService;

import java.util.List;

public class BookServiceImpl implements BookService {
    BookDao bookDao = new BookDao();
    @Override
    public List<Book> getbook() {
        return bookDao.getbooks();
    }

    @Override
    public int addbook(Book book) {

        return bookDao.addbook(book);
    }

    @Override
    public boolean getbookname(Book book) {
        return bookDao.getbookname(book);
    }

    @Override
    public void alterBook(Book book, Book book1) {
        bookDao.alterBook(book, book1);
    }

    @Override
    public void deleteBook(Book book) {
        bookDao.deleteBook(book);
    }
}

测试类Test代码 

import com.xszx.controller.UserController;

//测试类
public class Test {
    public static void main(String[] args) {
        System.out.println("欢迎来到小张图书管理系统！！！");
        new UserController().menu();
    }
}