java idea中做一个简易的图书管理系统（控制台输入输出，无数据库）

1：先创建增删改查四个接口

（1）QueryBook查询接口

package com.by.dao;import com.by.entity.Book;public interface QueryBook {/*** 查询所有图书信息* @param bs*/void selectBook(Book[] bs);/*** 根据名字查询一个图书信息* @param bookName* @param bs*/void selectBookByBookname(String bookName,Book[] bs);
}

（2）AddBook 增加接口

package com.by.dao;import com.by.entity.Book;public interface AddBook {/*** 在原图书数组末尾添加一个图书信息* @param book   被添加的图书对象* @param bs     图书数组* @return*/Book [] insertBook(Book book,Book[] bs);
}

（3）RemoveBook删除接口

package com.by.dao;import com.by.entity.Book;public interface RemoveBook {/*** 删除指定图书对象* @param bookName  删除的图书名，图书对象* @param bs   返回的数组* @return*/Book[] deleteBooksByName(String bookName, Book[] bs);
}

（4）UpdateBook修改接口

package com.by.dao;import com.by.entity.Book;public interface UpdateBook {/*** 根据图书名修改图书信息* @param bookName 图书名* @param bs   数组中内容改变*/void setBookByName(String bookName,Book book,Book []bs);
}

2：创建用户类实现查询接口

package com.by.entity;import com.by.dao.QueryBook;import java.util.Scanner;public class User implements QueryBook {private String userName;private String password;public User() {}public User(String userName, String password) {this.userName = userName;this.password = password;}public String getUserName() {return userName;}public void setUserName(String userName) {this.userName = userName;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}@Overridepublic void selectBook(Book[] bs) {for (int i = 0; i <bs.length; i++) {System.out.println("图书名"+bs[i].getBookName()+" , "+"作者名"+bs[i].getBookAuthor()+" , "+"价格"+bs[i].getBookPrice()+" , "+"库存"+bs[i].getBookInventory());}}@Overridepublic void selectBookByBookname(String bookName, Book[] bs) {for (int i = 0; i <bs.length ; i++) {if (bookName.equals(bs[i].getBookName())){System.out.println("图书名"+bs[i].getBookName()+" , "+"作者名"+bs[i].getBookAuthor()+" , "+"价格"+bs[i].getBookPrice()+" , "+"库存"+bs[i].getBookInventory());}}}/*  Scanner sc=new Scanner(System.in);public void login(){System.out.println("欢迎使用图书管理系统，请先登录");Scanner sc=new Scanner(System.in);System.out.println("请输入用户名：");String name=sc.nextLine();if (name.equals(this.userName)){System.out.println("请输入密码：");String password=sc.nextLine();if(password.equals(this.password)){System.out.println("登录成功");}else{System.out.println("用户名或密码有误");}}else{System.out.println("请输入密码：");String password1=sc.nextLine();System.out.println("用户名或密码错误");}*//*else {System.out.println("用户名错误");}*//*}*//* public void selectBook(){System.out.println("请输入操作指令");int num=sc.nextInt();switch (num){case 1:case 2:}}*/
}

3：创建普通用户继承用户，管理员账户继承用户类并实现增删改接口

（1）普通用户NormalUser类

package com.by.entity;import com.by.dao.QueryBook;import java.util.Scanner;public class NormalUser extends User {public NormalUser() {}public NormalUser(String userName, String password) {super(userName, password);}/* @Overridepublic void login() {System.out.println("欢迎使用图书管理系统，请先登录");Scanner sc=new Scanner(System.in);System.out.println("请输入用户名：");String name=sc.nextLine();if (name.equals(this.getUserName())){System.out.println("请输入密码：");String password=sc.nextLine();if(password.equals(this.getPassword())){System.out.println("登录成功");}else{System.out.println("用户名或密码有误");}}else{System.out.println("请输入密码：");String password1=sc.nextLine();System.out.println("用户名或密码错误");}}*/
}

（2）管理员用户AdminUser类

package com.by.entity;import com.by.dao.AddBook;
import com.by.dao.QueryBook;
import com.by.dao.RemoveBook;
import com.by.dao.UpdateBook;import java.util.Scanner;public class AdminUser extends User implements AddBook, UpdateBook, RemoveBook {public AdminUser() {}public AdminUser(String userName, String password) {super(userName, password);}Scanner sc = new Scanner(System.in);@Overridepublic Book[] insertBook(Book book, Book[] bs) {Book[] bs1 = new Book[bs.length + 1];for (int i = 0; i < bs.length; i++) {bs1[i] = bs[i];}bs1[bs.length] = book;return bs1;}@Overridepublic Book[] deleteBooksByName(String bookName, Book[] bs) {Book[] bs2 = new Book[bs.length - 1];for (int i = 0; i < bs.length; i++) {if (bs[i].getBookName().equals(bookName)) {for (int i1 = i; i1 < bs2.length; i1++) {bs2[i] = bs[i + 1];}} else {bs2[i] = bs[i];}}return bs2;}/* @Overridepublic void setBookByName(String bookName,Book[] bs) {for (int i=0;i< bs.length;i++){if (bookName.equals(bs[i].getBookName())){bs[i]=book;}}}*/@Overridepublic void setBookByName(String bookName, Book book, Book[] bs) {for (int i = 0; i < bs.length; i++) {if (bookName.equals(bs[i].getBookName())) {bs[i] = book;}}//    @Override
//    public void setBookByName(String bookName, Book[] bs) {
//
//    }/* @Overridepublic void login() {System.out.println("欢迎使用图书管理系统，请先登录");Scanner sc=new Scanner(System.in);System.out.println("请输入用户名：");String name=sc.nextLine();if (name.equals(this.getUserName())){System.out.println("请输入密码：");String password=sc.nextLine();if(password.equals(this.getPassword())){System.out.println("登录成功");System.out.println("请输入操作：1:添加图书");insertBook();}else{System.out.println("用户名或密码有误");}}else{System.out.println("请输入密码：");String password1=sc.nextLine();System.out.println("用户名或密码错误");}}@Overridepublic void selectBook() {System.out.println("请输入操作指令");int num=sc.nextInt();switch (num) {case 1:case 2:case 3:case 4:case 5:}}*/}
}

4：创建图书类存放图书的属性 

package com.by.entity;public class Book {private String bookName;private String bookAuthor;private double bookPrice;private int bookInventory;//库存public Book(){}public Book(String bookName,String bookAuthor,double bookPrice,int bookInventory){this.bookName=bookName;this.bookAuthor=bookAuthor;this.bookPrice=bookPrice;this.bookInventory=bookInventory;}public String getBookName(){return bookName;}public void setBookName(String bookName){this.bookName=bookName;}public String getBookAuthor() {return bookAuthor;}public void setBookAuthor(String bookAuthor) {this.bookAuthor = bookAuthor;}public double getBookPrice() {return bookPrice;}public void setBookPrice(double bookPrice) {this.bookPrice = bookPrice;}public int getBookInventory() {return bookInventory;}public void setBookInventory(int bookInventory) {this.bookInventory = bookInventory;}
}

5：创建测试类测试

package com.by.test;import com.by.entity.AdminUser;
import com.by.entity.NormalUser;
import com.by.entity.User;
import com.by.entity.Book;import java.sql.SQLOutput;
import java.util.Scanner;public class MainTest {public static void main(String[] args) {User[] users = {new AdminUser("张三", "123"), new NormalUser("李四", "321"),new NormalUser("王五", "456"), new NormalUser("haha", "123")};Book[] bs = {new Book("西游记", "吴承恩", 49.9, 999),new Book("三国演义", "罗贯中", 48.9, 888),new Book("水浒传", "施耐庵", 47.9, 777),new Book("红楼梦", "曹雪芹", 46.9, 666)};User user = login(users);fonction(user, bs);}public static User login(User[] users) {boolean result = false;System.out.println("欢迎使用图书管理系统，请先登录");Scanner sc = new Scanner(System.in);System.out.println("请输入用户名：");String name = sc.nextLine();System.out.println("请输入密码：");String password = sc.nextLine();for (int i = 0; i < users.length; i++) {if (name.equals(users[i].getUserName()) && password.equals(users[i].getPassword())) {System.out.println("登录成功");result = true;return users[i];}}System.out.println("用户名或密码错误，登录失败！");return null;}public static void fonction(User user, Book[] bs) {boolean a=true;while(a) {System.out.println("请选择你要进行的操作：1，查看所有图书信息  2。查看指定图书信息  " +" 3，添加图书信息   4，修改图书信息    5，删除图书信息    6，退出");Scanner scanner = new Scanner(System.in);int sum = scanner.nextInt();switch (sum) {case 1:user.selectBook(bs);break;case 2:System.out.println("请输入图书名：");String name = scanner.next();user.selectBookByBookname(name, bs);break;case 3:if (isAdmin(user)) {AdminUser adminUser = (AdminUser) user;System.out.println("请输入书名：");String bookName = scanner.next();System.out.println("作者");String author = scanner.next();System.out.println("请输入价格");double price = scanner.nextDouble();System.out.println("请输入库存");int kucun = scanner.nextInt();Book book = new Book(bookName, author, price, kucun);Book[] bs1 = adminUser.insertBook(book, bs);user.selectBook(bs1);} else {System.out.println("对不起，您太拉了，权限不够");}break;case 4:if (isAdmin(user)) {System.out.println("请输入你要修改的图书");String byname = scanner.next();AdminUser adminUser = (AdminUser) user;System.out.println("请输入改成的图书名");String gaiName=scanner.next();System.out.println("请输入作者");String author=scanner.next();System.out.println("请输入价格");double price=scanner.nextDouble();System.out.println("请输入库存");int kucun=scanner.nextInt();Book book=new Book(gaiName,author,price,kucun);adminUser.setBookByName(byname, book,bs);user.selectBook(bs);} else {System.out.println("对不起，您太拉了，权限不够");}break;case 5:if (isAdmin(user)) {System.out.println("请输入要删除的图书");String deleteName = scanner.next();AdminUser adminUser = (AdminUser) user;Book[] bs2=adminUser.deleteBooksByName(deleteName, bs);user.selectBook(bs2);break;}case 6:System.out.println("欢饮下次使用！");a=false;break;default:System.out.println("输入有误，请重新输入");break;}}}public static boolean isAdmin(User user) {if (user instanceof AdminUser) {return true;} else {return false;}}}