1.简介

通过前面知识：类，抽象类，封装，继承，多态，接口的学习，这篇文章将会通过对学习的知识点的整合运用，写一个小项目——图书管理系统，来帮助大家更好的掌握前面学习的知识点。

2.设计需求

1. 根据用户信息进行登录（选择身份）

2. 管理员身份

• 查找图书
• 新增图书
• 删除图书
• 显示图书
• 退出系统

3. 普通用户身份

• 查找图书
• 借阅图书
• 归还图书
• 退出系统

3.相关类的设计

根据设计需求，我们分析所需要的类.

1. 首先是图书类 -> 先创建 package book包 -> 创建 Book 类, 表示一本书，创建 BookList 类, 用来保存 N 本书.

2. 接着是操作类 ->先创建 package operation包 -> 根据功能创建操作类

    							AddOperation  -> 新增图书BrowOperation -> 借阅图书DelOperation -> 删除图书ExitOperation -> 退出系统FindOperation	-> 查找图书							ReturnOperation -> 归还图书ShowOperation -> 显示图书
   

根据操作类来设计一个接口IOPeration。

3. 然后创建用户类 -> 先创建 package user包 -> 创建 User 类, 这是一个抽象类,创建普通用户类, 是 User 的子类创建管理员用户类。

4. 最后创建测试类Main 来测试下代码的基本框架是否存在问题。

4.图书类

1.Book类

package book;/*** Created with IntelliJ IDEA.* Description:书籍信息* User: 28144* Date: 2022-11-27* Time: 18:59*/
public class Book {private String name;//名字private String author;//作者private int price;//价格private String type;//类型private boolean isBorrowed;//是否被借出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 double 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;}@Overridepublic String toString() {return "Book{" +"name='" + name + '\'' +", author='" + author + '\'' +", price=" + price +", type='" + type +(isBorrowed == true ? "  已近被借出" : "  未被借出")+ '}';}
}

2. BookList类

package book;/*** Created with IntelliJ IDEA.* Description:书架* User: 28144* Date: 2022-11-27* Time: 19:06*/
public class BookList {private Book[] books = new Book[10];private int usedSize;//来记录当前books数组当中有多少本书public BookList() {books[0] = new Book("三国演义","罗贯中",89,"小说");books[1] = new Book("西游记","吴承恩",59,"小说");books[2] = new Book("红楼梦","曹雪芹",189,"小说");this.usedSize = 3;}public Book getBook(int pos) {return this.books[pos];}public void setBook(Book book) {this.books[usedSize] = book;}public void setBook(int pos,Book book) {this.books[pos] = book;}public int getUsedSize() {return usedSize;}public void setUsedSize(int usedSize) {this.usedSize = usedSize;}
}

5.操作类

操作的接口：

package opera;import book.BookList;/*** Created with IntelliJ IDEA.* Description:* User: 28144* Date: 2022-11-27* Time: 19:16*/
public interface IOPeration {void work(BookList bookList);
}

1.新增图书

package opera;import book.Book;
import book.BookList;import java.util.Scanner;/*** Created with IntelliJ IDEA.* Description:* User: 28144* Date: 2022-11-27* Time: 19:18*/
public class AddOperation implements IOPeration{@Overridepublic void work(BookList bookList) {System.out.println("新增图书！");Scanner scanner = new Scanner(System.in);System.out.println("输入书名：");String name = scanner.nextLine();System.out.println("输入作者：");String author = scanner.nextLine();System.out.println("请输入类型：");String type = scanner.nextLine();System.out.println("输入价格：");int price = scanner.nextInt();Book book = new Book(name,author,price,type);int currentSize = bookList.getUsedSize();for (int i = 0; i < currentSize; i++) {Book tmp = bookList.getBook(i);if(tmp.getName().equals(name)) {System.out.println("这本书已经存在，不能再放入!");return;}}bookList.setBook(book);//修改usedSizebookList.setUsedSize(currentSize + 1);}
}

2.借阅图书

package opera;import book.Book;
import book.BookList;import java.util.Scanner;/*** Created with IntelliJ IDEA.* Description:* User: 28144* Date: 2022-11-27* Time: 19:25*/
public class BrowOperation implements IOPeration{@Overridepublic void work(BookList bookList) {System.out.println("借阅图书！");System.out.println("输入你要借阅的图书：");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.isBorrowed()) {book.setBorrowed(true);System.out.println("借阅成功！");return;}}System.out.println("借阅失败！");}
}

3.删除图书

package opera;import book.Book;
import book.BookList;import java.util.Scanner;/*** Created with IntelliJ IDEA.* Description:* User: 28144* Date: 2022-11-27* Time: 19:21*/
public class DelOperation implements IOPeration{@Overridepublic void work(BookList bookList) {System.out.println("删除图书！");System.out.println("请输入你要删除图书的名字：");Scanner scanner = new Scanner(System.in);String name = scanner.nextLine();int currentSize = bookList.getUsedSize();int index = -1;for (int i = 0; i < currentSize; i++) {Book tmp = bookList.getBook(i);if(tmp.getName().equals(name)) {index = i;break;}}//挪动数据for (int j = index; j < currentSize - 1; j++) {Book book = bookList.getBook(j + 1);bookList.setBook(j,book);}//修改SizebookList.setUsedSize(currentSize - 1);//因为删除的是对象，所以把最后一个置为nullbookList.setBook(currentSize - 1,null);System.out.println("删除成功！");}
}

4.查找图书

package opera;import book.Book;
import book.BookList;import java.util.Scanner;/*** Created with IntelliJ IDEA.* Description:* User: 28144* Date: 2022-11-27* Time: 19:20*/
public class FindOperation implements IOPeration{@Overridepublic 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名字：");Scanner sc = new Scanner(System.in);String name = sc.nextLine();int currentSize = bookList.getUsedSize();for (int i = 0; i < currentSize; i++) {Book book = bookList.getBook(i);if(book.getName().equals(name)) {System.out.println("找到了这本书");System.out.println(book);return;}}System.out.println("没有这本书！");}
}

5.归还图书

package opera;import book.Book;
import book.BookList;import java.util.Scanner;/*** Created with IntelliJ IDEA.* Description:* User: 28144* Date: 2022-11-27* Time: 19:25*/
public class ReturnOperation implements IOPeration{@Overridepublic void work(BookList bookList) {System.out.println("归还图书！");System.out.println("输入你要归还的图书：");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.isBorrowed()) {book.setBorrowed(false);System.out.println("归还成功！");return;}}System.out.println("归还失败！");}
}

6.显示图书

package opera;import book.Book;
import book.BookList;/*** Created with IntelliJ IDEA.* Description:* User: 28144* Date: 2022-11-27* Time: 19:22*/
public class ShowOperation implements IOPeration{@Overridepublic void work(BookList bookList) {System.out.println("打印所有图书！");int currentSize = bookList.getUsedSize();for (int i = 0; i < currentSize; i++) {Book book = bookList.getBook(i);System.out.println(book);}}
}

7.退出系统

package opera;import book.BookList;/*** Created with IntelliJ IDEA.* Description:* User: 28144* Date: 2022-11-27* Time: 19:24*/
public class ExitOperation implements IOPeration{@Overridepublic void work(BookList bookList) {System.out.println("退出系统！");System.exit(0);}
}

6.用户类

1.User类

创建 User类, 这是一个抽象类

package user;import book.BookList;
import opera.IOPeration;/*** Created with IntelliJ IDEA.* Description:* User: 28144* Date: 2022-11-27* Time: 19:12*/
public abstract class User {protected String name;protected IOPeration[] ioPerations;public User(String name) {this.name = name;}public abstract int menu();public void dowork(int choice, BookList bookList) {this.ioPerations[choice].work(bookList);}
}

2.普通用户类

创建普通用户类, 是 User 的子类.

package user;import opera.*;import java.util.Scanner;/*** Created with IntelliJ IDEA.* Description:* User: 28144* Date: 2022-11-27* Time: 19:14*/
public class NormalUser extends User{public NormalUser(String name) {super(name);this.ioPerations = new IOPeration[] {new ExitOperation(),new FindOperation(),new BrowOperation(),new ReturnOperation(),};}public int menu() {System.out.println("********************************");System.out.println("hello " + name + " 欢迎来到图书小练习");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;}
}

3.管理员类

创建管理员用户类.

package user;import opera.*;import java.util.Scanner;/*** Created with IntelliJ IDEA.* Description:* User: 28144* Date: 2022-11-27* Time: 19:13*/
public class AdminUser extends User {public AdminUser(String name) {super(name);this.ioPerations = new IOPeration[] {new ExitOperation(),new FindOperation(),new AddOperation(),new DelOperation(),new ShowOperation(),};}public int menu() {System.out.println("********************************");System.out.println("hello " + name + " 欢迎来到图书小练习");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;}
}

7.测试类

import book.Book;
import book.BookList;
import user.AdminUser;
import user.NormalUser;
import user.User;import java.util.Scanner;/*** Created with IntelliJ IDEA.* Description:* User: 28144* Date: 2022-11-27* Time: 19:32*/
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 0->普通用户");int choice = scanner.nextInt();if(choice == 1) {return new AdminUser(name);}else {return new NormalUser(name);}}public static void main(String[] args) {BookList bookList = new BookList();User user = login();while (true) {int choice = user.menu();//根据choice和user来确定调用那个对象的那个操作。user.dowork(choice, bookList);}}
}