• JavaSE——图书管理

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    作者：敲代码の流川枫

    博客主页：流川枫的博客

    专栏：和我一起学java

    语录：Stay hungry stay foolish

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    点击免费注册和我一起刷题吧  

    文章目录

    前言

    book

    Book

    BookList

    operation

    IOperation

    AddOperation

    BorrowOperation

    DelOperation

    DisplayOperation

    ExitOperation

    FindOperation

    ReturnOperation

    user

    User

    AdminUser

    NormalUser

    Main

    前言

    以面向对象的思想找到并且抽象出图书管理所需要的对象，再分析这些类和对象应该具有哪些属性和方法，对象通过“属性”和“方法”来分别对应事物所具有的静态属性和动态属性，最后分析类和类之间具体有什么关系，通过各个对象间的交互，使用对象、类、继承、封装、接口等基本概念完成序设计 

    抽象出来的对象有：书，书架，用户等，分别建立三个包管理 

    book

    Book

    1. package book;
    2. public class Book {
    3.     //书名
    4.     private String  name;
    5.     //作者
    6.     private String author;
    7.     //价格
    8.     private int price;
    9.     //类型
    10.     private String type;
    11.     //状态
    12.     private boolean isBorrow;
    13.     public Book(String name, String author, int price, String type) {
    14.         this.name = name;
    15.         this.author = author;
    16.         this.price = price;
    17.         this.type = type;
    18.  
    19.     }
    20.     @Override
    21.     public String toString() {
    22.         return "Book{" +
    23.                 "name='" + name + '\'' +
    24.                 ", author='" + author + '\'' +
    25.                 ", price=" + price +
    26.                 ", type='" + type + '\'' +
    27.                 ((isBorrow==true)?"已借出":"未借出")+
    28.                 '}';
    29.     }
    30.     public String getName() {
    31.         return name;
    32.     }
    33.  
    34.     public void setName(String name) {
    35.         this.name = name;
    36.     }
    37.  
    38.     public String getAuthor() {
    39.         return author;
    40.     }
    41.  
    42.     public void setAuthor(String author) {
    43.         this.author = author;
    44.     }
    45.  
    46.     public int getPrice() {
    47.         return price;
    48.     }
    49.  
    50.     public void setPrice(int price) {
    51.         this.price = price;
    52.     }
    53.  
    54.     public String getType() {
    55.         return type;
    56.     }
    57.  
    58.     public void setType(String type) {
    59.         this.type = type;
    60.     }
    61.  
    62.     public boolean isBorrow() {
    63.         return isBorrow;
    64.     }
    65.  
    66.     public void setBorrow(boolean borrow) {
    67.         isBorrow = borrow;
    68.     }
    69. }

    BookList

    先存储三本书：

    1. package book;
    2.  
    3. public class BookList {
    4.     private Book[] books = new Book[10];
    5.     private int usedSize;//存储当前书的个数
    6.  
    7.     public BookList() {
    8.  
    9.         books[0] = new Book("三国演义","罗贯中",90,"小说");
    10.         books[1] = new Book("红楼梦","曹雪芹",80,"小说");
    11.         books[2] = new Book("水浒传","施耐庵",70,"小说");
    12.  
    13.         this.usedSize = 3;
    14.     }
    15.  
    16.     public int getUsedSize() {
    17.         return usedSize;
    18.     }
    19.  
    20.     public void setUsedSize(int usedSize) {
    21.         this.usedSize = usedSize;
    22.     }
    23.     public Book getPos(int pos){
    24.         return books[pos];
    25.  
    26.     }
    27.     //存储一本书到指定的位置
    28.     public void setBooks(Book book,int pos){
    29.         books[pos] = book;
    30.     }
    31. }
    32. //将对数组的操作写到一个接口中

    operation

    IOperation

    1. package operation;
    2.  
    3. import book.BookList;
    4.  
    5. public interface IOperation {
    6.     void work(BookList bookList);
    7. }

    AddOperation

    1. package operation;
    2.  
    3. import book.Book;
    4. import book.BookList;
    5.  
    6. import java.util.Scanner;
    7.  
    8. public class AddOperation implements IOperation{
    9.     //添加图书
    10.     public void work(BookList bookList){
    11.         System.out.println("添加图书");
    12.  
    13.         System.out.println("请输入书名");
    14.         Scanner scanner = new Scanner(System.in);
    15.         String name = scanner.nextLine();
    16.         System.out.println("请输入作者");
    17.         String  author = scanner.nextLine();
    18.         System.out.println("请输入价格");
    19.         int price = scanner.nextInt();
    20.         //读取回车
    21.         scanner.nextLine();
    22.         System.out.println("请输入类型");
    23.         String type = scanner.nextLine();
    24.  
    25.         Book book =  new Book(name,author,price,type);
    26.         //获取可以存放的位置
    27.         int currentSize = bookList.getUsedSize();
    28.         //放到指定位置
    29.         bookList.setBooks(book,currentSize);
    30.         //书的个数加一
    31.         bookList.setUsedSize(currentSize+1);
    32.     }
    33. }

    BorrowOperation

    1. package operation;
    2.  
    3. import book.Book;
    4. import book.BookList;
    5.  
    6. import java.util.Scanner;
    7.  
    8. public class BorrowOperation implements IOperation{
    9.     public void work(BookList bookList){
    10.         System.out.println("借阅图书");
    11.         System.out.println("请输入书名");
    12.         Scanner scanner = new Scanner(System.in);
    13.         String name = scanner.nextLine();
    14.         //遍历是否有要借阅的书并记录下标
    15.         int index = -1;
    16.         int currentSize = bookList.getUsedSize();
    17.         for (int i = 0; i < currentSize ; i++) {
    18.             Book book = bookList.getPos(i);
    19.             if(name.equals(book.getName())){
    20.                 if(book.isBorrow()){
    21.                     System.out.println("已借出");
    22.                 }
    23.                 else{
    24.                     book.setBorrow(true);
    25.                     System.out.println("借阅成功");
    26.                 }
    27.                 return;
    28.             }
    29.         }
    30.         System.out.println("没有要借阅的书");
    31.     }
    32. }

    DelOperation

    1. package operation;
    2.  
    3. import book.Book;
    4. import book.BookList;
    5.  
    6. import java.util.Scanner;
    7.  
    8. public class DelOperation implements IOperation{
    9.     public void work(BookList bookList){
    10.         System.out.println("删除图书");
    11.         System.out.println("请输入书名");
    12.         Scanner scanner = new Scanner(System.in);
    13.         String name = scanner.nextLine();
    14.  
    15.         //遍历是否有要删除的书并记录下标
    16.         int index = -1;
    17.         int currentSize = bookList.getUsedSize();
    18.         for (int i = 0; i < currentSize ; i++) {
    19.             Book book = bookList.getPos(i);
    20.             if(name.equals(book.getName())){
    21.                 index = i;
    22.                 break;
    23.             }
    24.         }
    25.         if(index == -1){
    26.             System.out.println("没有要删除的书");
    27.             return ;
    28.         }
    29.         for (int i = index; i < currentSize-1 ; i++) {
    30.  
    31.             Book book = bookList.getPos(i+1);
    32.             bookList.setBooks(book,i);
    33.         }
    34.         
    35.         bookList.setBooks(null,currentSize-1);
    36.  
    37.         //重置有效长度
    38.         bookList.setUsedSize(currentSize-1);
    39.         System.out.println("删除成功");
    40.     }
    41. }

    假设有四本书，那么i+1最大值就是3，即 i < currentSize-1才不会越界

    删除书之后要置空，否则可能会出现内存泄漏
    一个对象没有人引用才会回收 

    DisplayOperation

    1. package operation;
    2.  
    3. import book.Book;
    4. import book.BookList;
    5.  
    6. public class DisplayOperation implements IOperation{
    7.     public void work(BookList bookList){
    8.         System.out.println("显示图书");
    9.         int currentSize = bookList.getUsedSize();
    10.         for (int i = 0; i < currentSize ; i++) {
    11.             Book book = bookList.getPos(i);
    12.             System.out.println(book);
    13.         }
    14.     }
    15. }

    ExitOperation

    1. package operation;
    2.  
    3. import book.BookList;
    4. import com.sun.xml.internal.ws.api.model.wsdl.WSDLOutput;
    5.  
    6. public class ExitOperation implements IOperation{
    7.     public void work(BookList bookList){
    8.         System.out.println("退出系统");
    9.         System.exit(0);
    10.     }
    11. }

    FindOperation

    1. package operation;
    2.  
    3. import book.Book;
    4. import book.BookList;
    5.  
    6. import java.util.Scanner;
    7.  
    8. public class FindOperation implements IOperation{
    9.     //查找图书
    10.     public void work(BookList bookList){
    11.         System.out.println("查找图书");
    12.         System.out.println("请输入书名：");
    13.         Scanner scanner = new Scanner(System.in);
    14.         String name = scanner.nextLine();
    15.         int currentSize = bookList.getUsedSize();
    16.         for (int i = 0; i < currentSize ; i++) {
    17.             Book book = bookList.getPos(i);
    18.             if(name.equals(book.getName())){
    19.                 System.out.println(book);
    20.                 return;
    21.             }
    22.         }
    23.         System.out.println("没有这本书");
    24.     }
    25. }

    ReturnOperation

    1. package operation;
    2.  
    3. import book.Book;
    4. import book.BookList;
    5.  
    6. import java.util.Scanner;
    7.  
    8. public class ReturnOperation implements IOperation{
    9.     public void work(BookList bookList){
    10.  
    11.         System.out.println("归还图书");
    12.         System.out.println("请输入书名");
    13.         Scanner scanner = new Scanner(System.in);
    14.         String name = scanner.nextLine();
    15.  
    16.         int index = -1;
    17.         int currentSize = bookList.getUsedSize();
    18.         for (int i = 0; i < currentSize ; i++) {
    19.             Book book = bookList.getPos(i);
    20.             if(name.equals(book.getName())){
    21.                 book.setBorrow(false);
    22.                 System.out.println("归还成功");
    23.                 return;
    24.             }
    25.         }
    26.         System.out.println("没有要归还的书");
    27.     }
    28.  
    29.  
    30. }

    user

    User

    1. package user;
    2.  
    3. import book.BookList;
    4. import operation.IOperation;
    5.  
    6. public abstract class User {
    7.     protected String name;
    8.     //只是定义数组， 没有初始化，内存没有分配
    9.     protected IOperation[] iOperations;
    10.     public User(String name) {
    11.         this.name = name;
    12.     }
    13.     public abstract int menu();
    14.     public void doOperation (int choice, BookList bookList){
    15.         iOperations[choice].work(bookList);
    16.  
    17.     }
    18. }

     需要写一个操作接口数组的方法doOperation()

    AdminUser

    1. package user;
    2.  
    3. import operation.*;
    4.  
    5. import java.util.Scanner;
    6.  
    7. //管理员
    8. public class AdminUser extends User{
    9.     public AdminUser(String name) {
    10.         super(name);
    11.         this.iOperations = new IOperation[]{
    12.                 new ExitOperation(),
    13.                 new FindOperation(),
    14.                 new AddOperation(),
    15.                 new DelOperation(),
    16.                 new DisplayOperation()
    17.  
    18.         };
    19.  
    20.     }
    21.  
    22.     public int menu(){
    23.         System.out.println("*************");
    24.         System.out.println("hello"+name+"欢迎来到图书管理");
    25.         System.out.println("1. 查找图书");
    26.         System.out.println("2. 新增图书");
    27.         System.out.println("3. 删除图书");
    28.         System.out.println("4. 显示图书");
    29.         System.out.println("0. 退出系统");
    30.         System.out.println("*************");
    31.         System.out.println("请输入你的操作：");
    32.  
    33.         Scanner scanner = new Scanner(System.in);
    34.         int choice = scanner.nextInt();
    35.         return choice;
    36.  
    37.     }
    38. }

    NormalUser

    1. package user;
    2.  
    3. import operation.*;
    4.  
    5. import java.util.Scanner;
    6.  
    7. //普通用户
    8. public class NormalUser extends User {
    9.     public NormalUser(String name) {
    10.         super(name);
    11.         this.iOperations = new IOperation[]{
    12.                 new ExitOperation(),
    13.  
    14.                 new FindOperation(),
    15.                 new BorrowOperation(),
    16.                 new ReturnOperation()
    17.  
    18.         };
    19.     }
    20.  
    21.     public int menu() {
    22.         System.out.println("*************");
    23.         System.out.println("hello" + name + "欢迎来到图书管理");
    24.         System.out.println("1. 查找图书");
    25.         System.out.println("2. 借阅图书");
    26.         System.out.println("3. 归还图书");
    27.         System.out.println("0. 退出系统");
    28.         System.out.println("*************");
    29.         System.out.println("请输入你的操作：");
    30.         Scanner scanner = new Scanner(System.in);
    31.         int choice = scanner.nextInt();
    32.         return choice;
    33.     }
    34.  
    35. }

    Main

    1. import book.BookList;
    2. import user.AdminUser;
    3. import user.NormalUser;
    4. import user.User;
    5.  
    6. import java.util.Scanner;
    7.  
    8. public class Main {
    9.     //利用向上转型确定是哪个对象
    10.     public static  User login(){
    11.         System.out.println("请输入你的姓名");
    12.         Scanner scanner =  new Scanner(System.in);
    13.         String userName = scanner.nextLine();
    14.         System.out.println("请输入你的身份：1. 管理员  2. 用户");
    15.         int choice = scanner.nextInt();
    16.         if(choice==1){
    17.            return new AdminUser(userName);
    18.         }
    19.         else{
    20.             return new NormalUser(userName);
    21.         }
    22.     }
    23.  
    24.     public static void main(String[] args) {
    25.         //先放三本书
    26.         BookList bookList = new BookList();
    27.         //登录
    28.         User user =  login();
    29.         while(true){
    30.             int choice = user.menu();
    31.             user.doOperation(choice,bookList);
    32.         }
    33.     }
    34. }

    当引用的对象不同时，会打印不同的菜单

     

    “ 本期的分享就到这里了， 记得给博主一个三连哈，你的支持是我创作的最大动力！

    ced485cbb11e458d81a746890b32cf3f.gif

     

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  • 原文地址：https://blog.csdn.net/chenchenchencl/article/details/126316673