实现的基本功能：

登录时，需要输入姓名，然后选择作为管理者还是普通用户。选择成功后选择想要实现的功能。管理者的目录下方有有五个功能，而普通用户有4个功能，如下图

首先我们要建立Book这个类，里面包含书本的详细信息

public class Book {private String name;private String author;private int price;private String type;private boolean isLend;public Book(String name, String author, int price, String type) {this.name = name;this.author = author;this.price = price;this.type = type;}//并不需要将是否借出作为参数，因为每一本书在增添的时候都默认没有借出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 isLend() {return isLend;}public void setLend(boolean lend) {isLend = lend;}public String toString() {return "book{" +"书名 " + name + "  " +"作者 " + author + "  " +"价格 " + price +"类型 " + type + "  " +"是否借出 " + (isLend?"已借出":"未借出") +'}';}}

要设置一个书架，里面建立一个数组来放书：

 private Book[] books=new Book[10];private int usedSize;public BookList() {books[0]=new Book("三国演义","罗贯中",10,"小说");books[1]=new Book("西游记","吴承恩",12,"小说");books[2]=new Book("红楼梦","曹雪芹",11,"小说");this.usedSize =3;}public int getUsedSize() {return usedSize;}public void setUsedSize(int usedSize) {this.usedSize = usedSize;}public Book[] getBooks() {return books;}public void setBooks(Book[] books) {this.books = books;}public Book getBook(int pos){return books[pos];}public void setBook(Book book,int pos){books[pos]=book;}public boolean isFull(){if(this.usedSize==books.length){return true;}else {return false;}}
}

设置主函数：

public class Main {public static User login(){System.out.println("请输入你的名字");Scanner scanner=new Scanner(System.in);String name=scanner.nextLine();System.out.println("请输入你的身份：1，管理员  2，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();user.doOperation(choice, bookList);}}

面对的有两类人，一类为普通用户，另一类为管理者，建立两个类，他们均继承User这个类，因为这个User这个类不用实现对象，所以为一个抽象类

public abstract class User  {private String name;IOperation [] iOperations=new IOperation[]{};public User(String name) {this.name = name;}public  abstract int menu();public void doOperation(int choice, BookList bookList){this.iOperations[choice].work(bookList);}}

public class AdminUser extends User{public AdminUser(String name) {super(name);this.iOperations=new IOperation[]{new ExitSystem(),new FindBook(),new AddBook(),new DelBook(),new ShowBook()};}public int menu(){System.out.println("********管理员菜单**********");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("请输入你操作");Scanner scanner=new Scanner(System.in);int choice=scanner.nextInt();return choice;}
}

public class NormalUser extends User {public NormalUser(String name) {super(name);this.iOperations=new IOperation[]{new ExitSystem(),new FindBook(),new LendBook(),new ReturnBook()};}public int  menu(){System.out.println("********普通用户菜单*********");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");Scanner scanner=new Scanner(System.in);int choice=scanner.nextInt();return choice;}}

实现各个功能：

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

新增图书

public class AddBook  implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("新增图书");if (bookList.isFull()==true){System.out.println("满了不能放");return;}System.out.println("请输入新增图书的书名：");Scanner scanner=new Scanner(System.in);String bookName=scanner.nextLine();System.out.println("请输入新增书的作者");String author=scanner.nextLine();System.out.println("请输入新增书的价格");int price=scanner.nextInt();scanner.nextLine();System.out.println("请输入新增书的类型");String type=scanner.nextLine();Book book=new Book(bookName,author,price,type);int current=bookList.getUsedSize();bookList.setBook(book,current);bookList.setUsedSize(current+1);System.out.println("新增图书成功");}
}

删除图书

public class DelBook  implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("删除图书");System.out.println("请输入要删除的书名：");Scanner scanner=new Scanner(System.in);String bookName=scanner.nextLine();int currentSize= bookList.getUsedSize();int pos=-1;int i = 0;for (; i <currentSize ; i++) {Book book=bookList.getBook(i);if(book.getName().equals(bookName)){System.out.println("找到这本书，开始删除");pos=i;break;}}if(i>=currentSize){System.out.println("没有找到这本书");return;}for (int j = pos; j <currentSize-1 ; j++) {Book book=bookList.getBook(j+1);bookList.setBook(book,j);}bookList.setUsedSize(currentSize-1);bookList.setBook(null,currentSize-1);System.out.println("删除成功");}
}

退出系统

public class ExitSystem implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("退出系统");for (int i = 0; i < bookList.getUsedSize(); i++) {bookList.setBook(null,i);}System.exit(0);}
}

查找图书

public class FindBook  implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("查找图书");System.out.println("请输入要查找的书名：");Scanner scanner=new Scanner(System.in);String bookName=scanner.nextLine();int currentSize= bookList.getUsedSize();for (int i = 0; i <currentSize ; i++) {Book book=bookList.getBook(i);if(book.getName().equals(bookName)){System.out.println("找到了这本书");System.out.println(book);return;}}System.out.println("没有找到这本书");}
}

借书

public class LendBook  implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("借书");System.out.println("请输入要借阅的书名：");Scanner scanner=new Scanner(System.in);String bookName=scanner.nextLine();int currentSize= bookList.getUsedSize();for (int i = 0; i <currentSize ; i++) {Book book=bookList.getBook(i);if(book.getName().equals(bookName)){book.setLend(true);System.out.println("借阅成功");return;}}System.out.println("借阅失败");}
}
归还图书
public class ReturnBook  implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("ReturnBook");System.out.println("请输入要归还的书名：");Scanner scanner=new Scanner(System.in);String bookName=scanner.nextLine();int currentSize= bookList.getUsedSize();for (int i = 0; i <currentSize ; i++) {Book book=bookList.getBook(i);if(book.getName().equals(bookName)){book.setLend(false);System.out.println("归还成功");return;}}System.out.println("归还失败");}
}

显示图书

public class ShowBook  implements IOperation{@Overridepublic void work(BookList bookList) {System.out.println("显示图书");int currentSize= bookList.getUsedSize();for (int i = 0; i <currentSize ; i++) {Book book=bookList.getBook(i);System.out.println(book);}}
}