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Java-java教程
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1.输入姓名
2.选择身份
3.根据身份打印不同功能菜单
1.2 基本框架
B、具体思路
book（包）
operation（功能包）
user（使用者包）
C、代码实现book（包）
Book（书类）
package book;/** * User: gu'jiu * Date: 2022-05-18 * Time: 14:45 * Description:书 */public class Book { private String name;//书名 private String author;//作者 private double price;//价格 private String type;//类型 private boolean state;//书的状态（已借出or未借出） //对书进行初始化，书的状态不用进行初始化（默认未借出） public Book(String name, String author, double price, String type) { this.name = name; this.author = author; this.price = price; this.type = type; this.state = state; } 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 String getType() { return type; } public void setType(String type) { this.type = type; } public boolean isState() { return state; } public void setState(boolean state) { this.state = state; } @Override public String toString() { return "[" +"name='" + name + '\'' +", author='" + author + '\'' +", price=" + price +", type='" + type + '\'' +", " + (state == true ? "已借出" : "未借出") +']'; }}BookList（书架类）
package book;/** * User: gu'jiu * Date: 2022-05-18 * Time: 14:52 * Description:书架 */public class BookList { private Book[] books = new Book[10]; private int usedSize; public BookList() { books[0] = new Book("三国演义","罗贯中",19.9,"小说"); books[1] = new Book("西游记","吴承恩",29.9,"小说"); books[2] = new Book("红楼梦","曹雪芹",26.9,"小说"); usedSize = 3; } public Book getBooks(int pos) {//输入下标获取该下标的这本书 return books[pos]; } public void setBooks(int pos, Book book) {//输入下标和一本书，在该下标放入一本书 this.books[pos] = book; } public int getUsedSize() { return usedSize; } public void setUsedSize(int usedSize) { this.usedSize = usedSize; }}operation（功能包）
IOperation（功能接口）
package operation;import book.BookList;/** * User: gu'jiu * Date: 2022-05-18 * Time: 15:07 * Description:接口 */public interface IOperation { void work(BookList bookList);}FindOperation（查找图书）
package operation;import book.Book;import book.BookList;import java.util.Scanner;/** * User: gu'jiu * Date: 2022-05-18 * Time: 15:09 * Description:查找书籍信息 */public class FindOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println(); System.out.println("查找图书"); System.out.println("------------------------"); Scanner scanner = new Scanner(System.in); System.out.print("请输入书的名称:"); String name = scanner.nextLine(); //获取书架中图书数量 int size = bookList.getUsedSize(); //根据名字查找 for (int i = 0; i < size; i++) { Book book = bookList.getBooks(i); if (book.getName().equals(name)) {System.out.println(book);return; } } System.out.println("未找到该书。"); }}AddOperation（添加图书）
package operation;import book.Book;import book.BookList;import java.util.Scanner;/** * User: gu'jiu * Date: 2022-05-18 * Time: 15:04 * Description:新增书籍 */public class AddOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println(); System.out.println("添加图书"); System.out.println("------------------------"); Scanner scanner = new Scanner(System.in); System.out.print("请输入书名:"); String name = scanner.nextLine(); System.out.print("请输入作者:"); String author = scanner.nextLine(); System.out.print("请输入书的类型:"); String type = scanner.nextLine(); System.out.print("请输入价格:"); double price = scanner.nextDouble(); Book book = new Book(name, author, price, type); bookList.setBooks(bookList.getUsedSize(), book);//将书放入书架 bookList.setUsedSize(bookList.getUsedSize()+1);//书籍数量+1 }}DelOperation（删除图书）
package operation;import book.Book;import book.BookList;import java.util.Scanner;/** * User: gu'jiu * Date: 2022-05-18 * Time: 15:05 * Description:删除书籍 */public class DelOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println(); System.out.println("删除图书"); System.out.println("------------------------"); Scanner scanner = new Scanner(System.in); System.out.print("请输入要删除的书名:"); String name = scanner.nextLine(); //获取书架中现在有几本书 int size = bookList.getUsedSize(); int i = 0; //根据书名找到这个本书的下标 for (i = 0; i < size; i++) { Book book = bookList.getBooks(i); if (book.getName().equals(name)) {break; } } if (i == size) { System.out.println("删除失败，未找到该书。"); return; } //通过前移将书删除 for (i = 0; i < size - 1; i++) { bookList.setBooks(i,bookList.getBooks(i + 1)); } bookList.setUsedSize(bookList.getUsedSize()-1);//书架中图书数量-1 System.out.println("删除成功。"); }}BorrowOperation（借阅图书）
package operation;import book.Book;import book.BookList;import java.util.Scanner;/** * User: gu'jiu * Date: 2022-05-18 * Time: 15:05 * Description:借阅书籍 */public class BorrowOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println(); System.out.println("借阅图书"); System.out.println("------------------------"); Scanner scanner = new Scanner(System.in); System.out.print("请输入要借书的名称:"); String name = scanner.nextLine(); //获取书架中现在有几本书 int size = bookList.getUsedSize(); for (int i = 0; i < size; i++) { Book book = bookList.getBooks(i); //判断在书架中是否有这本书 if (book.getName().equals(name)) {//判断书是否被借走if (!book.isState()) { System.out.println("借阅成功！"); book.setState(true);//将书的状态改为已借出 return;} else { System.out.println("借阅失败，该书已被别人借走。"); return;} } } System.out.println("借阅失败，未找到该书。"); }}ReturnOperation（归还图书）
package operation;import book.Book;import book.BookList;import java.util.Scanner;/** * User: gu'jiu * Date: 2022-05-18 * Time: 15:10 * Description:归还书籍 */public class ReturnOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println(); System.out.println("归还图书"); System.out.println("------------------------"); Scanner scanner = new Scanner(System.in); System.out.print("请输入要还书的名称:"); String name = scanner.nextLine(); //获取书架中现在有几本书 int size = bookList.getUsedSize(); for (int i = 0; i < size; i++) { Book book = bookList.getBooks(i); //判断在书架中是否有这本书 if (book.getName().equals(name)) {//判断书是否已被借走if (book.isState()) { System.out.println("归还成功！"); book.setState(false);//将书的状态改为未借出 return;} else { System.out.println("归还失败，该书已还未被借走。"); return;} } } System.out.println("归还失败，未找到该书。"); }}DisplayOperation（打印图书信息）
package operation;import book.Book;import book.BookList;/** * User: gu'jiu * Date: 2022-05-18 * Time: 15:06 * Description:打印全部书籍信息 */public class DisplayOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println(); System.out.println("显示全部图书"); System.out.println("------------------------"); int size = bookList.getUsedSize(); for (int i = 0; i < size; i++) { Book book = bookList.getBooks(i); System.out.println(book); } }}ExitOperation（退出系统）
import book.BookList;/** * User: gu'jiu * Date: 2022-05-18 * Time: 15:08 * Description:退出系统 */public class ExitOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println(); System.out.println("退出系统。"); System.out.println("------------------------"); System.exit(0); }}user（使用者包）
User（使用者抽象类）
package user;import book.BookList;import operation.IOperation;/** * User: gu'jiu * Date: 2022-05-18 * Time: 15:11 * Description:使用者 */abstract public class User { protected String userName;//使用者姓名 protected IOperation[] iOperations;//功能数组 public User(String userName) { this.userName = userName; } public abstract int menu(); //输入选择，调用不同的功能 public void doOperation(int choice, BookList bookList) { this.iOperations[choice].work(bookList);//动态绑定 }}AdminUser（管理员）
package user;import operation.*;import java.util.Scanner;/** * User: gu'jiu * Date: 2022-05-18 * Time: 15:13 * Description:管理员 */public class AdminUser extends User{ public AdminUser(String userName) { super(userName); //管理员功能 this.iOperations = new IOperation[] {new ExitOperation(),new FindOperation(),new AddOperation(),new DelOperation(),new DisplayOperation() }; } @Override public int menu() { System.out.println(); System.out.println("hello " + this.userName + " 欢迎来到图书馆"); while(true) { System.out.println("------------------------"); 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.显示全部图书"); System.out.println("0.退出系统"); System.out.println("------------------------"); System.out.print("请输入你的操作:"); Scanner scanner = new Scanner(System.in); int choice = scanner.nextInt(); //保证输入数字有效 if (choice > 4 || choice < 0) {System.out.println("输入有误请重新输入。"); } else {return choice; } } }}NormalUser（普通用户）
package user;import operation.*;import java.util.Scanner;/** * User: gu'jiu * Date: 2022-05-18 * Time: 15:13 * Description:学生 */public class NormalUser extends User{ public NormalUser (String userName) { super(userName); //用户功能 this.iOperations = new IOperation[] {new ExitOperation(),new FindOperation(),new BorrowOperation(),new ReturnOperation(), }; } @Override public int menu() { System.out.println(); System.out.println("hello "+this.userName+" 欢迎来到图书馆"); while(true) { System.out.println("------------------------"); 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.print("请输入你的操作:"); Scanner scanner = new Scanner(System.in); int choice = scanner.nextInt(); //保证输入数字有效 if (choice > 3 || choice < 0) {System.out.println("输入有误请重新输入。"); } else {return choice; } } }}Test类
import book.BookList;import user.AdminUser;import user.NormalUser;import user.User;import java.util.Scanner;/** * User: gu'jiu * Date: 2022-05-18 * Time: 15:20 * Description:图书管理系统 */public class Test { public static User login() { System.out.println("欢迎使用图书管理系统"); Scanner scanner = new Scanner(System.in); System.out.print("请输入您的姓名:"); String name = scanner.nextLine(); while(true){ System.out.println("-----------------------------"); System.out.println("请选择您的身份:1>管理员 2>普通用户"); System.out.print("请输入："); int choice = scanner.nextInt(); //保证输入数字有效 if (choice == 1) {return new AdminUser(name); } else if (choice == 2) {return new NormalUser(name); } else {System.out.println("输入有误，请重新输入。"); } } } public static void main(String[] args) { BookList bookList = new BookList(); User user = login();//向上转型 while(true){ int choice = user.menu(); user.doOperation(choice, bookList); } }}D、部分代码（doOperation）解释
主函数中的user.doOperation(choice, bookList);中的doOperation方法比较难理解，我们来解释一下
1.user.引用的可能是两个对象
2.在实例化这对象的时候，在构造方法中，我们已经将iOperations[]准备好了。
3.根据输入下标（例如：2）访问相应对象，再调用work方法。
《java视频教学》