图书管理系统

前言

这次文章将带大家实现一个图书管理系统，界面如下：

在这里插入图片描述

找到对象

我们从上面就可以知道，我们需要创建两个对象，一个是管理员对象，一个是普通用户对象，由于这两个对象都是用户这一范畴，所以我们可以为他们创建一个父类，那我们可以将这三个类放在同一个包上，如下图所示：

在这里插入图片描述
然后我们进一步思考我们还需要什么类，由于这是一个图书管理系统，所以我们可以创建书这个类用来创建多本的书，我们还可以创建一个书架用来存放书籍，这两个类我们把他们放在同一个包上：

在这里插入图片描述

我们有很多个功能需要实现，例如增加图书，删除图书，查询图书等等…我们可以再创建一个包用来专门存放这些功能：

在这里插入图片描述

最后我们需要创建一个Main类用来组装上面的代码，使其成为一个管理系统。

代码实现

book包

Book类

这里的书包括书名，作者，书的类型，价格以及书是否被借出的状态，这样我们可以创建对应的成员变量，为了有封装的体现，我们可以使用private修饰这些创元变量，然后通过Getter and Setter 来实现成员变量的访问就可以了.

由于我们会访问这本书的所有信息，我们就需要打印，这时候我们就要重写toString 方法，尽管IDEA编译器会自动帮我们实现，但是对于书是否被借出的状态打印，我们需要打印字符串（“未借阅” 和 “已借阅”）这两种状态，但是这个成员变量是boolean类型的，所以我们如果不去修改toString 方法的话，我们就会得到false和true这两种打印形式，那么我们就要稍微修改一下代码，这时候我们可以使用三目表达式来进行修改

如果直接使用编译器自动生成 toString 代码：

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

结合上述的要点，我们可以得到下面的代码：

public class Book {
    private String name;
    private String author;
    private String type;
    private double price;
    private boolean is_borrowed;

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

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

    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 String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public boolean isIs_borrowed() {
        return is_borrowed;
    }

    public void setIs_borrowed(boolean is_borrowed) {
        this.is_borrowed = is_borrowed;
    }
}

BookList 类（书架）

我们可以使用组合来将书放在代码里，我们还可以先将三本书放在书架上，这时候我们可以通过构造方法来初始化书架，我们还需要知道书架上目前有多少本书，容量是多少，成员变量要相应的写上去，并且通过getter和setter方法来来实现成员变量的访问…

public class BookList {
    private Book[] books;
    private int curSize;
    private int count;

    public BookList(){
        books = new Book[10];
        books[0] = new Book("三国演义","罗贯中","名著",30.12);
        books[1] = new Book("西游记","吴承恩","名著",30.14);
        books[2] = new Book("红楼梦","曹雪芹","名著",50.42);

        curSize = 3;
        count = 10;
    }


    public int getCurSize() {
        return curSize;
    }

    public void setCurSize(int curSize) {
        this.curSize = curSize;
    }

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }

    public Book getBooks(int i) {
        return books[i];
    }

    public void setBooks(int pos,Book newBook) {
        books[pos] = newBook;
    }
}

user包

我们先来创建父类 User，需要姓名这一个成员变量，由于父类本身是要被继承的，所以我们可以将其实现为抽象类，不同的身份有不同的菜单列表，既然都是菜单我们不妨在父类写一个抽象方法，提醒子类要记得写菜单，还有用户会输入不同的数字来实现不同的功能，这里我们可以创建一个功能实现的方法，这样子我们就可以通过父类的引用来实现不同的子类所对应的功能…

public abstract class User {
    public String name;
    protected Ioperate[] opertions;

    public User(String name) {
        this.name = name;
    }

    public abstract int menu();

    public void work(int choice, BookList bookList){
        opertions[choice].operate(bookList);
    }
}

管理者

public class Manager extends User{
    public Manager(String name) {
        super(name);
        opertions = new Ioperate[] {
                new Exit(),
                new Find(),
                new Add(),
                new Delete(),
                new Show()
        };
    }

    @Override
    public int menu() {
        System.out.println("*******管理员菜单*******");
        System.out.println("       1.查询图书");
        System.out.println("       2.增加图书");
        System.out.println("       3.删除图书");
        System.out.println("       4.显示所有图书");
        System.out.println("       0.退出系统");
        System.out.println("************************");
        System.out.println("请输入你的选择：");
        Scanner scan = new Scanner(System.in);
        int choice = scan.nextInt();
        return choice;
    }
}

普通用户

public class DomesticConsumer extends User {

    public DomesticConsumer(String name) {
        super(name);
        opertions = new Ioperate[] {
                new Exit(),
                new Find(),
                new Borrow(),
                new Return()
        };
    }

    @Override
    public int menu() {
        System.out.println("*******普通用户菜单*******");
        System.out.println("       1.查询图书");
        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.println("请输入你的选择：");
        Scanner scan = new Scanner(System.in);
        int choice = scan.nextInt();
        return choice;
    }
}

Ioperation包

接口

我们可以通过一个接口来实现功能的有机联系，这样我们就可以通过这个接口类型来实现不同的方法，我们知道这些方法几乎都会操作书架，所以我们将书架作为参数进行传递就可以了。

public interface Ioperate {
    void operate(BookList bookList);
}

Add

我们直接采用尾插，我们需要判断一下书架是否还能继续放书，需要将目前的图书数目和书架容量进行比较就可以了，接下来就是创建新书，将新书放到书架即可，这时候我们要注意书架放书的代码是否正确，我们使用IDEA编译器只能实现Book[]类型的getter和setter，但是书的类型是Book，所以我们需要自己写一个放书的代码:

    public void setBooks(int pos,Book newBook) {
        books[pos] = newBook;
    }

为什么不直接写books[curSize] = newBook呢？

因为我们后面删除图书的代码里也是需要对书架上的书进行移动，会用到setter方法，所以为了代码的通用性高，我们就多加了一个pos参数

public class Add implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        int count = bookList.getCount();
        int curSize = bookList.getCurSize();
        if(count == curSize){
            System.out.println("书架已满，无法再放入别的图书.......");
            return;
        }

        System.out.println("请输入你要增加的书名:");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();
        System.out.println("请输入作者名字");
        String author = scan.nextLine();
        System.out.println("请输入图书类型：");
        String type = scan.nextLine();
        System.out.println("请输入图书价格：");
        double price = scan.nextDouble();

        Book newBook = new Book(name,author,type,price);
        bookList.setBooks(curSize,newBook);
        bookList.setCurSize(curSize + 1);
    }
}

在进行删除图书，查询图书，这里我采用的是通过书名进行遍历访问的方式。
这时候我们就要小心，因为我们是对书架进行操控的，所以我们要先拿到书这个对象，那我们就要看怎么拿出对应的书，由于编译器只能实现Book[]类型的getter，所以我们还是要自己写一个拿书的代码。
由于书名是String类型，所以可以使用equals方法经行字符串的比对。所以我们拿到书后还要访问书的书名再进行比对即可。

public Book getBooks(int i) {
        return books[i];
    }

			Book book = bookList.getBooks(i);
            if(book.getName().equals(name)){
                //......
                }

Delete

删除书也很容易，我们需要把待删除的书后面的书进行前移

public class Delete implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        int curSize = bookList.getCurSize();
        if(curSize == 0){
            System.out.println("书架已空，无法继续删除......");
        }

        System.out.println("请输入你要删除图书的书名：");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();

        for (int i = 0; i < curSize; i++) {
            Book book = bookList.getBooks(i);
            if(book.getName().equals(name)){
                System.out.println("删除成功......");
                for (int j = i; j < curSize - 1; j++) {
                    bookList.setBooks(j,bookList.getBooks(j+1));
                }
                bookList.setCurSize(curSize - 1);
                return;
            }
        }

        System.out.println("未查询到该书.....");
    }
}

Borrow

public class Borrow implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        System.out.println("请输入你要借阅图书书名：");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();

        int curSize = bookList.getCurSize();
        for (int i = 0; i < curSize; i++) {
            Book book = bookList.getBooks(i);
            if(book.getName().equals(name)){
                if(book.isIs_borrowed() == false){
                    System.out.println("该书已被你成功借阅......");
                    book.setIs_borrowed(true);
                }else{
                    System.out.println("该书已被借阅，无法被再次借阅.....");
                }
                return;
            }
        }

        System.out.println("未查询到此书......");
    }
}

Find

public class Find implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        System.out.println("输入你要查询的书名：");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();

        int count = bookList.getCurSize();
        for (int i = 0; i < count; i++) {
            Book book = bookList.getBooks(i);
            if(book.getName().equals(name)){
                System.out.println(book);
                return;
            }
        }

        System.out.println("未查询到此书......");
    }
}

Return

public class Return implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        System.out.println("请输入你要归还书名：");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();

        int count = bookList.getCurSize();
        for (int i = 0; i < count; i++) {
            Book book = bookList.getBooks(i);
            if(book.getName().equals(name)){
                if(book.isIs_borrowed() == true){
                    System.out.println("归还成功......");
                    book.setIs_borrowed(false);
                }else{
                    System.out.println("该图书已被归还到书架上，无需重复归还......");
                }
                return;
            }
        }

        System.out.println("未查询到该图书.....");
    }
}

Show

public class Show implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        int count = bookList.getCurSize();
        for (int i = 0; i < count; i++) {
            System.out.println(bookList.getBooks(i));
        }
    }
}

Exit

退出程序的代码就是System.exit(数字)，数字零表示正常退出的意思。

public class Exit implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        System.out.println("退出系统......");
        System.exit(0);
    }
}

    public static User login(){
        Scanner scan = new Scanner(System.in);
        System.out.println("请输入你的姓名：");
        String name = scan.nextLine();

        System.out.println("1.管理员   2.普通用户");
        System.out.println("请输入你的身份：");
        int identity = scan.nextInt();

        if(identity == 1){
            return new Manager(name);
        }else{
            return new DomesticConsumer(name);
        }
    }

主逻辑实现

我们先登录，然后创建书架，接着打印菜单，用户输入指令，计算机进行对应的操作：

    public static void main(String[] args) {
        //创建书架
        BookList bookList = new BookList();

        //login
        User user = login();

        while(true){

            //功能菜单选择
            int choice = user.menu();

            //功能实现
            user.work(choice,bookList);
        }
    }

最终代码

Main类

import book.BookList;
import user.DomesticConsumer;
import user.Manager;
import user.User;

import java.util.Scanner;

public class Main {
    public static User login(){
        Scanner scan = new Scanner(System.in);
        System.out.println("请输入你的姓名：");
        String name = scan.nextLine();

        System.out.println("1.管理员   2.普通用户");
        System.out.println("请输入你的身份：");
        int identity = scan.nextInt();

        if(identity == 1){
            return new Manager(name);
        }else{
            return new DomesticConsumer(name);
        }
    }

    public static void main(String[] args) {
        //创建书架
        BookList bookList = new BookList();

        //login
        User user = login();

        while(true){

            //功能菜单选择
            int choice = user.menu();

            //功能实现
            user.work(choice,bookList);
        }
    }
}

user包

User

package user;

import Ioperation.Ioperate;
import book.BookList;

public abstract class User {
    public String name;
    protected Ioperate[] opertions;

    public User(String name) {
        this.name = name;
    }

    public abstract int menu();

    public void work(int choice, BookList bookList){
        opertions[choice].operate(bookList);
    }
}

Manager

package user;

import Ioperation.*;

import java.util.Scanner;

public class Manager extends User{
    public Manager(String name) {
        super(name);
        opertions = new Ioperate[] {
                new Exit(),
                new Find(),
                new Add(),
                new Delete(),
                new Show()
        };
    }

    @Override
    public int menu() {
        System.out.println("*******管理员菜单*******");
        System.out.println("       1.查询图书");
        System.out.println("       2.增加图书");
        System.out.println("       3.删除图书");
        System.out.println("       4.显示所有图书");
        System.out.println("       0.退出系统");
        System.out.println("************************");
        System.out.println("请输入你的选择：");
        Scanner scan = new Scanner(System.in);
        int choice = scan.nextInt();
        return choice;
    }
}

DomesticConsumer

package user;

import Ioperation.*;

import java.util.Scanner;

public class DomesticConsumer extends User {

    public DomesticConsumer(String name) {
        super(name);
        opertions = new Ioperate[] {
                new Exit(),
                new Find(),
                new Borrow(),
                new Return()
        };
    }

    @Override
    public int menu() {
        System.out.println("*******普通用户菜单*******");
        System.out.println("       1.查询图书");
        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.println("请输入你的选择：");
        Scanner scan = new Scanner(System.in);
        int choice = scan.nextInt();
        return choice;
    }
}

book 包

Book

package book;

public class Book {
    private String name;
    private String author;
    private String type;
    private double price;
    private boolean is_borrowed;

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

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

    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 String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public boolean isIs_borrowed() {
        return is_borrowed;
    }

    public void setIs_borrowed(boolean is_borrowed) {
        this.is_borrowed = is_borrowed;
    }
}

BookList

package book;

public class BookList {
    private Book[] books;
    private int curSize;
    private int count;

    public BookList(){
        books = new Book[10];
        books[0] = new Book("三国演义","罗贯中","名著",30.12);
        books[1] = new Book("西游记","吴承恩","名著",30.14);
        books[2] = new Book("红楼梦","曹雪芹","名著",50.42);

        curSize = 3;
        count = 10;
    }


    public int getCurSize() {
        return curSize;
    }

    public void setCurSize(int curSize) {
        this.curSize = curSize;
    }

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }

    public Book getBooks(int i) {
        return books[i];
    }

    public void setBooks(int pos,Book newBook) {
        books[pos] = newBook;
    }
}

Ioperation包

Ioperate

package Ioperation;

import book.BookList;

public interface Ioperate {
    void operate(BookList bookList);
}

Add

package Ioperation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class Add implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        int count = bookList.getCount();
        int curSize = bookList.getCurSize();
        if(count == curSize){
            System.out.println("书架已满，无法再放入别的图书.......");
            return;
        }

        System.out.println("请输入你要增加的书名:");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();
        System.out.println("请输入作者名字");
        String author = scan.nextLine();
        System.out.println("请输入图书类型：");
        String type = scan.nextLine();
        System.out.println("请输入图书价格：");
        double price = scan.nextDouble();

        Book newBook = new Book(name,author,type,price);
        bookList.setBooks(curSize,newBook);
        bookList.setCurSize(curSize + 1);
    }
}

Borrow

package Ioperation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class Borrow implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        System.out.println("请输入你要借阅图书书名：");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();

        int curSize = bookList.getCurSize();
        for (int i = 0; i < curSize; i++) {
            Book book = bookList.getBooks(i);
            if(book.getName().equals(name)){
                if(book.isIs_borrowed() == false){
                    System.out.println("该书已被你成功借阅......");
                    book.setIs_borrowed(true);
                }else{
                    System.out.println("该书已被借阅，无法被再次借阅.....");
                }
                return;
            }
        }

        System.out.println("未查询到此书......");
    }
}

Delete

package Ioperation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class Delete implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        int curSize = bookList.getCurSize();
        if(curSize == 0){
            System.out.println("书架已空，无法继续删除......");
        }

        System.out.println("请输入你要删除图书的书名：");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();

        for (int i = 0; i < curSize; i++) {
            Book book = bookList.getBooks(i);
            if(book.getName().equals(name)){
                System.out.println("删除成功......");
                for (int j = i; j < curSize - 1; j++) {
                    bookList.setBooks(j,bookList.getBooks(j+1));
                }
                bookList.setCurSize(curSize - 1);
                return;
            }
        }

        System.out.println("未查询到该书.....");
    }
}

Exit

package Ioperation;

import book.BookList;

public class Exit implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        System.out.println("退出系统......");
        System.exit(0);
    }
}

Find

package Ioperation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class Find implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        System.out.println("输入你要查询的书名：");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();

        int count = bookList.getCurSize();
        for (int i = 0; i < count; i++) {
            Book book = bookList.getBooks(i);
            if(book.getName().equals(name)){
                System.out.println(book);
                return;
            }
        }

        System.out.println("未查询到此书......");
    }
}

Return

package Ioperation;

import book.Book;
import book.BookList;

import java.util.Scanner;

public class Return implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        System.out.println("请输入你要归还书名：");
        Scanner scan = new Scanner(System.in);
        String name = scan.nextLine();

        int count = bookList.getCurSize();
        for (int i = 0; i < count; i++) {
            Book book = bookList.getBooks(i);
            if(book.getName().equals(name)){
                if(book.isIs_borrowed() == true){
                    System.out.println("归还成功......");
                    book.setIs_borrowed(false);
                }else{
                    System.out.println("该图书已被归还到书架上，无需重复归还......");
                }
                return;
            }
        }

        System.out.println("未查询到该图书.....");
    }
}

Show

package Ioperation;

import book.BookList;

public class Show implements Ioperate{
    @Override
    public void operate(BookList bookList) {
        int count = bookList.getCurSize();
        for (int i = 0; i < count; i++) {
            System.out.println(bookList.getBooks(i));
        }
    }
}

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原文地址：https://blog.csdn.net/liwuqianhzc/article/details/139864703

图书管理系统

前言

找到对象

代码实现

book包

Book类

BookList 类 （书架）

user包

管理者

普通用户

Ioperation包

接口

Add

Delete

Borrow

Find

Return

Show

Exit

登录

主逻辑实现

最终代码

Main类

user包

User

Manager

DomesticConsumer

book 包

Book

BookList

Ioperation包

Ioperate

Add

Borrow

Delete

Exit

Find

Return

Show

BookList 类（书架）