1.系统导读
Java最主要的特征便是面向对象,这个小练习就是让我们加强对面向对象的理解,所以系统的实现肯定是通过分多个包和类来共同实现系统功能的。
该系统的通过四部分来实现:
1.book包下为图书信息的存储
2.user包下为用户的信息及操作逻辑
3.Main文件下为整个系统的逻辑实现
4.operation包下为系统功能的具体实现
首先是登陆页面,输入姓名后选择身份,然后跳转到不同的菜单(管理员和普通用户两份菜单),然后在用户进一步选择功能以后去实现对应的功能。
2.创建系统所需类
2.1图书信息(book包)
该系统是通过顺序表来实现的,在顺序表的数组中存储的是每一本书的信息,然后通过顺序表进行增删查改功能的实现(顺序表了解可以博主之前的文章【Java数据结构之顺序表】
Book.java
书需要包含书名、作者、价格、类型、是否被借出等信息
package book; public class Book { private String name; private String author; private int price; private String type; private boolean isBorrowed; 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() {//以下getter、setter实现通过idea中的快捷键alt+insert来实现 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 isBorrowed() { return isBorrowed; } public void setBorrowed(boolean borrowed) { isBorrowed = borrowed; } @Override //重写toString()方法是为了打印书的具体信息,如果不重写不会打印出书的具体内容 public String toString() { return "Book{" + "name='" + name + '\'' + ", author='" + author + '\'' + ", price=" + price + ", type='" + type + '\'' + ((isBorrowed==true)?"已被借出":"未被借出") + '}'; } }
BookList.java
package book; public class BookList { private Book [] books=new Book[10]; //顺序表数组,暂时先将长度设小,随着接下来的学习,该部分还会继续改进 private int useSize; //记录目前书的本数 public BookList() { //在构造方法中先存储三本书的信息 books[0] = new Book("三国演义","罗贯中",17,"小说"); books[1] = new Book("西游记","吴承恩",47,"小说"); books[2] = new Book("水浒传","施耐庵",37,"小说"); this.useSize=3; } public int getUseSize() { return useSize; } public void setUseSize(int useSize) { this.useSize = useSize; } //以下两个方法为手敲(非快捷键) public Book getPos(int pos) { return this.books[pos]; }//得到角标为pos位置的书 public void setBook(int pos,Book book) { this.books[pos] = book; }//将角标为pos位置的书改为函数传参传过来的book. }
2.2用户信息(user包)
因为使用者有管理者和普通用户两个对象,但两者多有相同属性且有细致区别的方法,所以将相同代码抽取出来创建抽象类User,再建立AdminUser和NormalUser分别继承User。
User.java
package user; import book.BookList; import operation.IOperation; public abstract class User { String name;//使用者姓名 IOperation[] iOperations; //创建使用者操作数组,数组内用于存储多项功能 public User(String name) { this.name = name; } public abstract int menu(); //两个对象的菜单不同,所以创建抽象方法 public void doWork(int choice, BookList bookList) { iOperations[choice].work(bookList); }//这个方法是在用户进行选择后,根据对应操作数组的选择进行不同操作 }
AdminUser.java
package user; import operation.*; import java.util.Scanner; public class AdminUser extends User { public AdminUser(String name) { super(name); this.iOperations = new IOperation[] { new ExitOperation(), new FindOperation(), new AddOperation(), new DelOperation(), new DisplayOperation() }; //构造方法内实例化不同对象对应的不同操作菜单 } //打印不同菜单 public int menu() { System.out.println("===========管理员菜单==========="); System.out.println("hello " + this.name +" 欢迎来到这里!"); 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("=============================="); Scanner scanner = new Scanner(System.in); int choice = scanner.nextInt(); return choice; //用户进行选择,选择后将choice值返回,调用实现对应功能 } }
NormalUser.java
package user; import operation.*; import java.util.Scanner; public class NormalUser extends User { public NormalUser(String name) { super(name); this.iOperations = new IOperation[] { new ExitOperation(), new FindOperation(), new BorrowOperation(), new ReturnOperation(), }; } public int menu() { System.out.println("===========普通用户的菜单==========="); System.out.println("hello " + this.name +" 欢迎来到这里!"); 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("=============================="); Scanner scanner = new Scanner(System.in); int choice = scanner.nextInt(); return choice; } }
3.系统逻辑(Main.java)
import book.BookList; import user.AdminUser; import user.NormalUser; import user.User; import java.util.Scanner; public class Main { //无论对象是谁,都需要先展示登录界面 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) { //根据choice的不同值,实例化不同对象并将其返回 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();//发生了动态绑定 -》 多态 //根据你的choice 调用合适的操作 user.doWork(choice, bookList); } } }
4.功能实现(operation包)
因为系统有多项功能,所以在这个包下,将每一个功能都独立创建为一个类来具体清晰实现,为了这些类中的代码复用,又抽象出来一个接口(多个类共有的功能)
Ioperation.java package operation; import book.BookList; import java.util.Scanner; public interface IOperation { Scanner scanner = new Scanner(System.in); void work(BookList bookList); }
AddOperation.java
新增图书需要new图书并将信息初始化,然后将其放在顺序表最后位置
package operation; import book.Book; import book.BookList; public class AddOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println("新增图书!"); System.out.println("请输入书名:"); String name = scanner.next(); System.out.println("请输入作者:"); String author= scanner.next(); System.out.println("请输入类型:"); String type=scanner.next(); System.out.println("请输入价格:"); int price=scanner.nextInt(); Book book=new Book(name, author,price,type); //实例化新增图书 int size= bookList.getUseSize(); //导包后调用bookList.getUseSize();函数确定新增图书存放位置 bookList.setBook(size,book); //新增图书 bookList.setUseSize(size+1); //有效书目加一 System.out.println("新增图书成功!"); } }
BorrowOperation.java
输入借阅图书书名后遍历数组查找,找到后将图书借阅情况更改
package operation; import book.Book; import book.BookList; public class BorrowOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println("借阅图书!"); System.out.println("请输入要借阅图书的名字"); String name=scanner.nextLine(); int size=bookList.getUseSize(); for (int i = 0; i < size; i++) { Book book=bookList.getPos(i); if (name.equals(book.getName())) { book.setBorrowed(true); System.out.println("借阅成功"); System.out.println(book); return; } } System.out.println("没有你要借阅的书"); } }
DelOperation.java package operation; import book.Book; import book.BookList; public class DelOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println("删除图书!"); System.out.println("请输入要删除的图书"); String name=scanner.next(); int size= bookList.getUseSize(); //设置循环先进行书目查找 for (int i = 0; i < size; i++) { Book book=bookList.getPos(i); //找到后数组前移覆盖此书 if (name.equals(book.getName())) { for (int j = i; j < size-1; j++) { Book bookNext=bookList.getPos(j+1); bookList.setBook(j,bookNext); } bookList.setBook(size,null); bookList.setUseSize(size-1); //删除书目后有效书目-1; System.out.println("删除完成"); return; } } System.out.println("该书不存在"); } }
DisplayOperation.java
把已有书目信息全部打印
package operation; import book.Book; import book.BookList; import java.util.Arrays; public class DisplayOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println("浏览图书!"); int size= bookList.getUseSize(); for (int i = 0; i < size; i++) { Book book=bookList.getPos(i); System.out.println(book); } } }
ExitOperation.java
退出系统
package operation; import book.BookList; public class ExitOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println("退出系统!"); System.exit(0); } }
FindOperation.java
package operation; import book.Book; import book.BookList; public class FindOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println("查找图书!"); System.out.println("请输入要查找的图书:"); String name=scanner.next(); int size= bookList.getUseSize(); for (int i = 0; i < size; i++) { Book book = bookList.getPos(i); if (name.equals(book.getName())) { System.out.println("找到了这本书,书的信息如下:"); System.out.println(book); return; } } System.out.println("没找到"); } }
ReturnOperation.java
package operation; import book.Book; import book.BookList; public class ReturnOperation implements IOperation{ @Override public void work(BookList bookList) { System.out.println("归还图书!"); System.out.println("请输入要归还图书的名字"); String name=scanner.nextLine(); int size=bookList.getUseSize(); for (int i = 0; i < size; i++) { Book book=bookList.getPos(i); if (name.equals(book.getName())) { book.setBorrowed(true); System.out.println("归还成功"); System.out.println(book); return; } } System.out.println("没有你要归还的书"); } }