一、项目分布

Book类: 定义了书的一些属性（书名，作者，价格，分类，状态）并且写了属性的get、set方法
Library类: 写了登录函数（1、普通用户，2、管理员，3、退出系统），
Person类：定义的人的属性（姓名，性别，年龄）并且写了属性的get、set方法，定义了一些书。
operate接口：操作的接口，操作方法：查询/查阅，删除/借阅，增加/还书，显示书籍列表
Root类：继承了Person类，实现operate（查阅，删除，增加，显示书籍列表）接口
User类：继承了Person类，实现operate（查询，借阅，还书，显示书籍列表）接口
Main类：Main中的主函数开启整个项目。

模型图：

二、代码展示：

1. Book类

class Book{private String name; //书名private String author; //作者public double price; //价格private String category; //分类private boolean state; //状态  true-未借出  false-已借出//通过构造函数给定书的属性public Book(String name,String author,double price,String category,boolean state){this.author = author;this.name = name;this.price = price;this.category = category;this.state = state;}public Book() {  //默认10本书this(10);}public Book(int i) { Person.books = new Book[i];}//属性的获取和设置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(double price) {this.price = price;}public boolean isState() {return state;}public void setState(boolean state) {this.state = state;}public String getCategory() {return category;}public void setCategory(String category) {this.category = category;}
}

2. Library类

import java.util.Scanner;public class Library {Scanner sc = new Scanner(System.in);//登录函数：显示登录界面进行选择登录public void login() { int count = 0;Person p = null;  while (count < 2) {  System.out.println("===============jewel图书管理系统===============");System.out.println("请登录：1.普通用户  2.管理员登录  3.退出系统");int n = sc.nextInt(); //通过输入的值进行登录判断if (n == 3) {return;} switch (n) {case 1:System.out.println("请输入姓名：");String Uname = sc.next();System.out.println("请输入性别：");String Usex = sc.next();System.out.println("请输入年龄：");int Uage = sc.nextInt();p = new User(Uname,Usex,Uage); //构造普通用户对象System.out.println("登录成功！");System.out.println("当前普通用户："+"姓名：" + p.getName() + " "+"性别：" + p.getSex() + " "+"年龄"+ p.getAge());//普通用户循环操作while (true) {System.out.println("请输入你的操作： 1.查询书籍 2.借阅书籍 3.归还书籍 4.显示书籍列表 5.退出");int i = sc.nextInt();if (i == 5) {System.out.println("您已成功退出！");break;}else {p.operate();  //调用普通用户的操作方法}}break;case 2:System.out.println("请输入管理员姓名：");String Rname = sc.next();System.out.println("请输入性别：");String Rsex = sc.next();System.out.println("请输入年龄：");int Rage = sc.nextInt();p = new Root(Rname,Rsex,Rage);//构造管理员对象System.out.println("登录成功！");System.out.println("当前管理员："+"姓名：" + p.getName() + " "+"性别：" + p.getSex() + " "+"年龄" + p.getAge());while (true) {System.out.println("请输入你的操作： 1.整理书籍 2.查阅书籍 3.增加书籍 4.删除书籍 5.显示书籍列表 6.退出");int j = sc.nextInt();if (j == 6) {System.out.println("您已成功退出！");break;}else{p.operate();//调用管理员的操作方法}} break;}}}
}

3. Person类（抽象类）

abstract  class Person  {   public String name;  //姓名public String sex;  //性别public int age;   // 年龄public static Book[] books = new Book[]{  //默认定义书籍new Book("西游记","吴承恩",10,"名著",true),new Book("红楼梦","曹雪芹",20,"名著",true),new Book("三国演义","罗贯中",15,"名著",true),new Book("小茗同学","小明",5,"杂志",true),new Book()};public Person(String name,String sex,int age) {this.age = age;this.name = name;this.sex = sex;}//get，set方法。public String getName() {return name;}public void setName(String name) {this.name = name;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public abstract void operate();//抽象类中的抽象方法}

4. operate接口

public interface operate{  //操作的接口void select(Book[] books); //查询，查阅void delete(Book[] books);//删除,借阅void add(Book[] books); //增加，还书void list(Book[] books); //显示书列表
}

5. Root类

import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;class Root extends Person implements operate {  //继承了人的类，需要重写它的抽象方法operate，实现了operate接口，需要重写接口内的方法private String Rname; private String Rsex;private int Rage;public Root(String name, String sex, int age) {super(name, sex, age);//调用人基类的构造函数}Scanner sc = new Scanner(System.in);@Overridepublic void operate() {   //管理员的操作System.out.print("请输入确认操作:");int i = sc.nextInt();switch (i) {case 1://整理   sort(books);break;case 2://查select(books);break;case 3://加add(books);break;case 4://删delete(books);break;case 5://列表list(books);break;default:System.out.println("输入有误！");break;}}//compareable整理，重写compare to，如果数组中有空的，则会出现空指针异常，把不空的拷到另一个新的数组，然后实现public void sort(Book[] books) {System.out.println("图书馆中的书按价格整理如下:");Arrays.sort(books, new Comparator<Book>() {@Overridepublic int compare(Book o1, Book o2) {return (int)(o1.getPrice()-o2.getPrice());}});for (int i = 0; i < books.length; i++) {  //遍历数组打印书的列表System.out.println(books[i].getName() + "   " + books[i].getAuthor() + "   " + books[i].getPrice() + "   " + books[i].getCategory() + "   " + books[i].isState());}System.out.println("整理结束！");}@Overridepublic void select(Book[] books) {System.out.println("请输入书名进行查询：");String name = sc.next();if(name != null) {for (int i = 0; i < books.length; i++) {if (books[i].getName().equals(name)) {System.out.println("有此书籍！");System.out.println("书籍信息为：（书名-作者-价格-分类-状态）");System.out.println(books[i].getName() + "   "+books[i].getAuthor() + "   "+books[i].getPrice() + "   "+books[i].getCategory() + "   "+books[i].isState());break;}System.out.println("暂时没有此书！");break;}}}@Overridepublic void delete(Book[] books) {System.out.println("请输入要删除的书名:");String str = sc.next();if(str != null) {for(int i = 0;i<books.length;i++) {if(books[i].getName().equals(str)) {books[i] = null;System.out.println("删除成功！");break;}}}}@Overridepublic void add(Book[] books) {System.out.println("请输入书名：");String name = sc.next();System.out.println("请输入作者：");String author = sc.next();System.out.println("请输入价格：");double price = sc.nextDouble();System.out.println("请输入分类：");String category = sc.next();for (int i = 0; i < books.length; i++) {if (books[i].getName() == null) {books[i].setName(name);books[i].setAuthor(author);books[i].setPrice(price);books[i].setCategory(category);books[i].setState(true);System.out.println("添加成功");break;}}}@Overridepublic void list (Book[]books){System.out.println("图书列表如下：（书名-作者-价格-分类-状态）");  //打印Book数组for (int i = 0; i < books.length; i++) {if (books[i] != null) {System.out.println(books[i].getName() + "   " + books[i].getAuthor() + "   " + books[i].getPrice() + "   " + books[i].getCategory() + "   " + books[i].isState());}}}
}

6. User类

import java.util.Scanner;User extends Person implements operate {   //user类继承了人的类，  实现operate接口private String Uname;private String Usex;private int Uage;public User(String name, String sex, int age) {super(name, sex, age); //调用人基类的构造函数（派生类不继承基类的构造函数）}Scanner sc = new Scanner(System.in);@Overridepublic void operate() {  //普通用户的操作System.out.print("请输入确认操作:");int i = sc.nextInt();switch (i) {case 1://查select(books);break;case 2: //借delete(books);break;case 3: //还add(books);break;case 4://书列表list(books);break;default:System.out.println("输入有误！");break;}}@Overridepublic void select(Book[] books) {System.out.println("请输入书名进行查询：");String name = sc.next();if(name != null) {for (int i = 0; i < books.length; i++) {if (books[i].getName().equals(name)) {System.out.println("有此书籍！");System.out.println("书籍信息为：（书名-作者-价格-分类-状态）");System.out.println(books[i].getName() + "   "+books[i].getAuthor() + "   "+books[i].getPrice() + "   "+books[i].getCategory() + "   "+books[i].isState());break;}System.out.println("暂时没有此书！");break;}}}@Overridepublic void delete(Book[] books) {System.out.println("请输入要借阅的书名:");String name = sc.next();if (name != null) {for (int i = 0; i < books.length-1; i++) {if (books[i].getName().equals(name)) {  //借走书时设置状态为falsebooks[i].setState(false);System.out.println("借阅成功！");break;} else {               //没书System.out.println("没有此书！");break;}}}}@Overridepublic void add(Book[] books) {System.out.println("请输入要还的书名：");String name = sc.next();if (name != null) {for (int j = 0; j < books.length-1; j++)if (books[j].getName().equals(name)) {books[j].setState(true);System.out.println("还书成功！");break;}}}@Overridepublic void list(Book[] books) {System.out.println("图书列表如下：（书名-作者-价格-分类-状态）");  //打印Book数组for (int i = 0; i < books.length; i++) {if (books[i] != null) {System.out.println(books[i].getName() + "   " + books[i].getAuthor() + "   " + books[i].getPrice() + "   " + books[i].getCategory() + "   " + books[i].isState());}}}
}

7. Main类

public class Main {public static void main(String[] args) {Library library = new Library(); //构造Library对象library.login(); //调用对象的登录方法。}
}

三、实现结果

1. 登录界面
   普通用户登录
   
   2.普通用户：查询、借阅、归还 、显示列表
   
   
   3.管理员登录，按图书价格整理书籍
   
2. 管理员添加书籍
   
3. 管理员删除书籍
   

如有错误欢迎讨论指正