前言

这个图书管理系统中包含了Java目前所学到的继承多态等等知识，是对Java面向对象部分的总结，不足之处还望多多包涵。

一、图书管理系统的总体框架是什么？

在这里插入图片描述

1.管理员的操作

2.普通用户的操作

二、具体的实现过程

1.创建关于书的一个包

①book类的具体实现

package book;

public class Book {
    private String name;//书名
    private String author;//作者
    private int price;//价格
    private String type;//类型
    private boolean isBorrowed;//是否被借出,默认是未借出的

    public Book(String name, String author, int price, String type) {
        this.name = name;
        this.author = author;
        this.price = price;
        this.type = type;
    }


    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;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Book{" +
                "name='" + name + '\'' +
                ", author='" + author + '\'' +
                ", price=" + price +
                ", type='" + type + '\'' +
                ((isBorrowed == true)?" 已借出":" 未借出")+
                '}';
    }
}

②booklist类的具体实现

package book;
//书架类
public class BookList {
    private Book[] books = new Book[10];//这个书架的大小
    private int usedSize;//数组中放了几本书
    public BookList() {
        books[0] = new Book("三国演义","罗贯中",90,"小说");
        books[1] = new Book("西游记","吴承恩",78,"小说");
        books[2] = new Book("红楼梦","曹雪芹",89,"小说");
        this.usedSize = 3;
    }

    /**
     * 获取当前数组中元素的个数
     * @return
     */
    public int getUsedSize() {
        return usedSize;
    }

    /**
     * 修改当前数组中元素的个数
     * @param usedSize
     */
    public void setUsedSize(int usedSize) {
        this.usedSize = usedSize;
    }

    /**
     * 获取下标为pos的书
     * @param pos
     * @return
     */
    public Book getPos(int pos) {
        return books[pos];
    }

    /**
     * 在下标pos位置添加一本书
     * @param pos
     * @param book
     */
    public void setBooks(int pos,Book book) {
        books[pos] = book;
    }


}

2.创建operation的一个包

在此实现我们具体的每个功能，创建相应的javaclass文件

①实现IOperation接口

package operation;

import book.BookList;

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

②增加图书（AddOperation）

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class AddOperation implements IOperation {
    public void work(BookList bookList){
        System.out.println("新增图书！");
        System.out.println("请输入图书的名字：");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();
        System.out.println("请输入图书的作者：");
        String author = scan.nextLine();
        System.out.println("请输入图书的类型：");
        String type = scan.nextLine();
        System.out.println("请输入图书的价格：");
        int price = scan.nextInt();
        Book book = new Book(name,author,price,type);
        int currentSize = bookList.getUsedSize();
        bookList.setBooks(currentSize,book);
        //以当前书的个数为下标增加这本书
        bookList.setUsedSize(currentSize+1);
        //然后将书的总数+1
        System.out.println("新增成功！");
    }
}

③借阅图书（BorrowOperation）

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class BorrowOperation implements IOperation{
    public void work(BookList bookList){
        System.out.println("借阅图书！");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();;
        System.out.println("请输入你要借阅的图书：");
        int currentSize = bookList.getUsedSize();
        for (int i = 0; i < currentSize; i++) {
            Book book = bookList.getPos(i);
            if(book.getName().equals(name)) {
                System.out.println("找到了这本书，内容如下：");
                System.out.println(book);
                if(book.isBorrowed()) {
                    System.out.println("抱歉，该书已被借出！");
                    return;
                    //如果已被借出，则结束本次借阅
                } else {
                    book.setBorrowed(true);
                    System.out.println("借阅成功！");
                    return;
                }
            }
        }
        System.out.println("没有你要借阅的图书！");
    }
}

④删除图书（DelOperation）

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class DelOperation implements IOperation{
    public void work(BookList bookList){
        System.out.println("删除图书！");
        System.out.println("请输入你要删除的图书：");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();
        int currentSize = bookList.getUsedSize();
        int index = 0;
        int i = 0;
        for ( ; i < currentSize; i++) {
            Book book = bookList.getPos(i);
            if(book.getName().equals(name)) {
                System.out.println("找到了这本书，内容如下：");
                System.out.println(book);
                index = i;
                break;
            }
        }
        if(index == currentSize) {
            System.out.println("要删除的这本书不存在！");
            return;
            //说明已经遍历完书架没找到这本书
        } else {
            for (int j = index; j < currentSize-1; j++) {
                Book book = bookList.getPos(j+1);//先获取出来再赋值
                bookList.setBooks(j,book);
            }
            bookList.setBooks(currentSize-1,null);
            bookList.setUsedSize(currentSize-1);
            System.out.println("删除成功！");
        }
    }
}

⑤退出系统（ExitOperation）

package operation;

import book.BookList;

public class ExitOperation implements IOperation {

    public void work(BookList bookList) {

        System.out.println("退出系统！");

        int currentSize = bookList.getUsedSize();

        for (int i = 0; i < currentSize; i++) {
            bookList.setBooks(i,null);
        }
        //将书架中的所有书都置为空
        System.exit(0);
    }
}

⑥查找图书（FindOperation）

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class FindOperation implements IOperation{
    public void work(BookList bookList){
        System.out.println("查找图书！");
        System.out.println("请输入你要查找的图书：");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();
        int currentSize = bookList.getUsedSize();
        for (int i = 0; i < currentSize; i++) {
            Book book = bookList.getPos(i);
            if(book.getName().equals(name)) {
                System.out.println("找到了这本书，内容如下：");
                System.out.println(book);
                return;
            }
        }
        System.out.println("没有这本书！");
    }
}

⑦归还图书（ReturnOperation）

package operation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class ReturnOperation implements IOperation {
    public void work(BookList bookList){
        System.out.println("归还图书！");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();;
        System.out.println("请输入你要归还的图书：");
        int currentSize = bookList.getUsedSize();
        for (int i = 0; i < currentSize; i++) {
            Book book = bookList.getPos(i);
            if(book.getName().equals(name)) {
                System.out.println("找到了这本书，内容如下：");
                System.out.println(book);
                book.setBorrowed(false);
                //归还后，这本书的状态便设置为未借出！
                System.out.println("归还成功！");
                return;
            }
        }
        System.out.println("没有你要归还的图书！");
        //可能书架中并没有你要归还的这本书，比如这本书你是从其他处借阅的
    }

}

⑧显示图书信息（ShowOperation）

package operation;

import book.Book;
import book.BookList;

public class ShowOperation implements IOperation{
    public void work(BookList bookList){
        System.out.println("显示图书信息！");
        int currentSize = bookList.getUsedSize();
        for (int i = 0; i < currentSize; i++) {
            Book book = bookList.getPos(i);
            System.out.println(book);
        }
    }
}

3.创建关于用户的一个包

①User（父类）

package user;

import book.BookList;
import operation.IOperation;

public abstract class User {
    protected  String name;//protect目的是防止被其他包继承
    //.......用户的更多属性
    public IOperation[] iOperations;//不初始化，接口数组
    //我们将不用身份用户所能进行的操作全部放入这个接口数组中
    public User(String name) {
        this.name = name;//构造函数
    }
    public abstract int menu();//菜单，不用用户引用的菜单menu不同，即为多态：同一个方法，
    //因为调用这个方法的引用，引用对象不同，所执行的行为也是不同的。
    public void doOperation(int choice,BookList bookList) {
        iOperations[choice].work(bookList);
    }
    //接口数组中具体要进行的某一项操作
}

② AdminUser （子类）

package user;

import operation.*;

import java.util.Scanner;

public class AdminUser extends User {
    public AdminUser(String name) {
        super(name);//构造子类时，优先构造父类
        this.iOperations = new IOperation[] {
                new ExitOperation(),
                new FindOperation(),
                new AddOperation(),
                new DelOperation(),
                new ShowOperation()
        };//将管理员能进行的操作都放入这个接口数组中
    }
    public int menu() {
        System.out.println("hello "+this.name+" 欢迎来到图书小练习!");
        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("请输入你要进行的操作：");//以上是管理员的菜单menu
        Scanner a = new Scanner(System.in);
        int choice = a.nextInt();
        return choice;//返回我们要进行的操作给主函数
    }
}

③NormalUser（子类）

package user;

import operation.*;

import java.util.Scanner;

public class NormalUser extends  User{
    public NormalUser(String name) {
        super(name);//当构造子类时，先构造父类的构造方法
        this.iOperations = new IOperation[] {
                new ExitOperation(),
                new FindOperation(),
                new BorrowOperation(),
                new ReturnOperation()
        };
    }
    public int menu() {
        System.out.println("hello "+this.name+" 欢迎来到图书小练习!");
        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("请输入你要进行的操作：");//普通用户菜单menu
        Scanner a = new Scanner(System.in);
        int choice = a.nextInt();
        return choice;//返回我们要进行的操作给主函数
    }
}

4.主函数（Main方法）

import book.BookList;
import user.AdminUser;
import user.NormalUser;
import user.User;

import java.util.Scanner;

public class Main {
    public static User login(){
        System.out.println("请输入姓名： ");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();
        System.out.println("请输入你的身份: 1->> 管理员,0->> 普通用户");
        int choice = scan.nextInt();//选择身份
        if(choice == 1) {
            return new AdminUser(name);//创建一个管理员对象
        } else {
            return new NormalUser(name);//创建一个普通用户对象
        }
    }
    public static void main(String[] args) {
        BookList bookList = new BookList();
        User user = login();//user 到底是谁？管理员or普通用户
        while(true){
            int choice = user.menu();
            //怎么知道调用的是哪个菜单? ——>>user创建的用户所应的菜单
            //接收菜单中要进行的操作
            user.doOperation(choice,bookList);
            //对书架实行对应的操作
        }
    }
}