C++ 实现图书馆资料管理系统

1、问题描述：

图书馆中的资料很多，如果能分类对其资料流通进行管理，将会带来很多方便，因此需要有一个媒体库管理系统。图书馆共有三大类物品资料：图书、视频光盘、图画。这三类物品共同具有的属性有：编号、标题、作者、评级（未评级，一般成人，儿童）等。其中图书类增加出版社、ISBN号、页数等信息；视频光盘类增加出品者的名字、出品年份和视频时长等信息；图画类增加出品国籍、作品的长和宽（以厘米计，整数）等信息。读者：基本信息，可借阅本数管理员：负责借阅

2、功能要求：

(1)添加物品：主要完成图书馆三类物品信息的添加，要求编号唯一。当添加了重复的编号时，则提示数据添加重复并取消添加：查询物品可按照三种方式来查询物品，分别为：按标题查询：输入标题，输出所查询的信息，若不存在该记录，则提示“该标题+存在！”；按编号查询：输入编号，输出所查询的信息，若不存在该记录，则提示“该编号不存在！”；按类别查询：输入类别，输出所查询的信息，若不存在记录，则提示“该类别没有物品！”；

(2)显示物品库：输出当前物品库中所有物品信息，每条记录占据一行。

(3)编辑物品：可根据查询结果对相应的记录进行修改，修改时注意编号的唯一性。

(4)删除物品：主要完成图书馆物品信息的删除。如果当前物品库为空，则提示“物品库为空！”，并返回操作：否则，输入要删除的编号，根据编号删除该物品的记录，如果该编号不在物品库中，则提示“该编号不存在”。

(5)借阅，管理员负责将物品借阅给读者，数据保存到文件中。

(6)统计信息输出当前物品库中总物品数，以及按物品类别，统计出山前物品中各类别的物品数并显。

(7)物品存盘：将当前程序中的物品信息存入文件中。

(8)读出物品从文件中将物品信息读入程序。开发完代码后需要进行测试，如果报错请修改，知道各项功能都可以正常运行。

#include <iostream>
#include <vector>
#include <string>
#include <fstream>
#include <unordered_map>
#include <windows.h>
using namespace std;enum Rating { UNRATED, ADULT, CHILD };string ratingToString(Rating rating) {switch (rating) {case UNRATED: return "未评级";case ADULT: return "成人";case CHILD: return "儿童";default: return "";}
}class Media {
public:int id;string title;string author;Rating rating;Media(int id, string title, string author, Rating rating): id(id), title(title), author(author), rating(rating) {}virtual void display() const {cout << "ID: " << id << ", 标题: " << title << ", 作者: " << author << ", 评级: " << ratingToString(rating) << endl;}virtual ~Media() {}
};class Book : public Media {
public:string publisher;string isbn;int pages;Book(int id, string title, string author, Rating rating, string publisher, string isbn, int pages): Media(id, title, author, rating), publisher(publisher), isbn(isbn), pages(pages) {}void display() const override {Media::display();cout << "出版社: " << publisher << ", ISBN: " << isbn << ", 页数: " << pages << endl;}
};class Video : public Media {
public:string producer;int year;int duration;Video(int id, string title, string author, Rating rating, string producer, int year, int duration): Media(id, title, author, rating), producer(producer), year(year), duration(duration) {}void display() const override {Media::display();cout << "出品者: " << producer << ", 年份: " << year << ", 时长: " << duration << " mins" << endl;}
};class Picture : public Media {
public:string nationality;int length;int width;Picture(int id, string title, string author, Rating rating, string nationality, int length, int width): Media(id, title, author, rating), nationality(nationality), length(length), width(width) {}void display() const override {Media::display();cout << "国籍: " << nationality << ", 尺寸: " << length << "x" << width << " cm" << endl;}
};class Library {unordered_map<int, Media*> mediaCollection;public:~Library() {for (auto& pair : mediaCollection) {delete pair.second;}}void addMedia(Media* media) {if (mediaCollection.find(media->id) != mediaCollection.end()) {cout << "检测到重复的 ID, 未添加资料." << endl;delete media;return;}mediaCollection[media->id] = media;cout << "资料添加成功." << endl;}void queryByTitle(const string& title) {bool found = false;for (const auto& pair : mediaCollection) {if (pair.second->title == title) {pair.second->display();found = true;}}if (!found) cout << " 标题 \"" << title << "\" 不存在!" << endl;}void queryById(int id) {if (mediaCollection.find(id) != mediaCollection.end()) {mediaCollection[id]->display();} else {cout << " ID \"" << id << "\" 不存在!" << endl;}}void queryByType(const string& type) {bool found = false;for (const auto& pair : mediaCollection) {if ((type == "Book" && dynamic_cast<Book*>(pair.second)) ||(type == "Video" && dynamic_cast<Video*>(pair.second)) ||(type == "Picture" && dynamic_cast<Picture*>(pair.second))) {pair.second->display();found = true;}}if (!found) cout << "分类没有 \"" << type << "\" 找到!" << endl;}void displayAll() {if (mediaCollection.empty()) {cout << "数据库中没有相关资料." << endl;return;}for (const auto& pair : mediaCollection) {pair.second->display();}}void editMedia(int id, Media* newMedia) {if (mediaCollection.find(id) == mediaCollection.end()) {cout << " ID \"" << id << "\" 不存在!" << endl;delete newMedia;return;}delete mediaCollection[id];mediaCollection[id] = newMedia;cout << "资料编辑成功." << endl;}void deleteMedia(int id) {if (mediaCollection.find(id) == mediaCollection.end()) {cout << " ID \"" << id << "\" 不存在!" << endl;return;}delete mediaCollection[id];mediaCollection.erase(id);cout << "资料删除成功." << endl;}void saveToFile(const string& filename) {ofstream file(filename, ios::binary);if (!file) {cout << "无法打开文件进行写入." << endl;return;}for (const auto& pair : mediaCollection) {Media* media = pair.second;file.write((char*)&media->id, sizeof(media->id));size_t length = media->title.size();file.write((char*)&length, sizeof(length));file.write(media->title.c_str(), length);length = media->author.size();file.write((char*)&length, sizeof(length));file.write(media->author.c_str(), length);file.write((char*)&media->rating, sizeof(media->rating));if (Book* book = dynamic_cast<Book*>(media)) {char type = 'B';file.write(&type, sizeof(type));length = book->publisher.size();file.write((char*)&length, sizeof(length));file.write(book->publisher.c_str(), length);length = book->isbn.size();file.write((char*)&length, sizeof(length));file.write(book->isbn.c_str(), length);file.write((char*)&book->pages, sizeof(book->pages));} else if (Video* video = dynamic_cast<Video*>(media)) {char type = 'V';file.write(&type, sizeof(type));length = video->producer.size();file.write((char*)&length, sizeof(length));file.write(video->producer.c_str(), length);file.write((char*)&video->year, sizeof(video->year));file.write((char*)&video->duration, sizeof(video->duration));} else if (Picture* picture = dynamic_cast<Picture*>(media)) {char type = 'P';file.write(&type, sizeof(type));length = picture->nationality.size();file.write((char*)&length, sizeof(length));file.write(picture->nationality.c_str(), length);file.write((char*)&picture->length, sizeof(picture->length));file.write((char*)&picture->width, sizeof(picture->width));}}cout << "数据保存到文件." << endl;}void loadFromFile(const string& filename) {ifstream file(filename, ios::binary);if (!file) {cout << "无法打开文件进行读取." << endl;return;}while (file.peek() != EOF) {int id;file.read((char*)&id, sizeof(id));size_t length;file.read((char*)&length, sizeof(length));string title(length, ' ');file.read(&title[0], length);file.read((char*)&length, sizeof(length));string author(length, ' ');file.read(&author[0], length);Rating rating;file.read((char*)&rating, sizeof(rating));char type;file.read(&type, sizeof(type));if (type == 'B') {file.read((char*)&length, sizeof(length));string publisher(length, ' ');file.read(&publisher[0], length);file.read((char*)&length, sizeof(length));string isbn(length, ' ');file.read(&isbn[0], length);int pages;file.read((char*)&pages, sizeof(pages));mediaCollection[id] = new Book(id, title, author, rating, publisher, isbn, pages);} else if (type == 'V') {file.read((char*)&length, sizeof(length));string producer(length, ' ');file.read(&producer[0], length);int year, duration;file.read((char*)&year, sizeof(year));file.read((char*)&duration, sizeof(duration));mediaCollection[id] = new Video(id, title, author, rating, producer, year, duration);} else if (type == 'P') {file.read((char*)&length, sizeof(length));string nationality(length, ' ');file.read(&nationality[0], length);int length, width;file.read((char*)&length, sizeof(length));file.read((char*)&width, sizeof(width));mediaCollection[id] = new Picture(id, title, author, rating, nationality, length, width);}}cout << "从文件加载的数据." << endl;}void countItems() {cout << "Total items: " << mediaCollection.size() << endl;int books = 0, videos = 0, pictures = 0;for (const auto& pair : mediaCollection) {if (dynamic_cast<Book*>(pair.second)) books++;else if (dynamic_cast<Video*>(pair.second)) videos++;else if (dynamic_cast<Picture*>(pair.second)) pictures++;}cout << "Books: " << books << ", Videos: " << videos << ", Pictures: " << pictures << endl;}
};int main() {SetConsoleOutputCP(65001);Library library;while (true) {cout << "欢迎使用图书馆资料管理系统: \n1. 添加资料\n2. 按标题查询资料\n3. 按ID查询资料\n4. 按类别查询资料\n5. 显示所有资料\n6. 编辑资料\n7. 删除资料\n8. 资料存盘\n9. 读取资料\n10. 统计资料\n11. 退出\n";int choice;cin >> choice;if (choice == 1) {cout << "选择类别: 1. 图书 2. 视频 3. 图画\n";int type;cin >> type;int id;string title, author;int rating;cout << "输入ID: ";cin >> id;cout << "输入标题: ";cin.ignore();getline(cin, title);cout << "输入作者: ";getline(cin, author);cout << "输入评级 (0 未评级, 1 成人, 2 儿童): ";cin >> rating;if (type == 1) {string publisher, isbn;int pages;cout << "输入出版社: ";cin.ignore();getline(cin, publisher);cout << "输入ISBN: ";getline(cin, isbn);cout << "输入页数: ";cin >> pages;library.addMedia(new Book(id, title, author, static_cast<Rating>(rating), publisher, isbn, pages));} else if (type == 2) {string producer;int year, duration;cout << "输入出品者: ";cin.ignore();getline(cin, producer);cout << "输入出品年份: ";cin >> year;cout << "输入时长(分钟): ";cin >> duration;library.addMedia(new Video(id, title, author, static_cast<Rating>(rating), producer, year, duration));} else if (type == 3) {string nationality;int length, width;cout << "输入出品国籍: ";cin.ignore();getline(cin, nationality);cout << "输入长度(厘米): ";cin >> length;cout << "输入宽度（厘米): ";cin >> width;library.addMedia(new Picture(id, title, author, static_cast<Rating>(rating), nationality, length, width));}} else if (choice == 2) {string title;cout << "输入标题: ";cin.ignore();getline(cin, title);library.queryByTitle(title);} else if (choice == 3) {int id;cout << "输入ID: ";cin >> id;library.queryById(id);} else if (choice == 4) {string type;cout << "输入类别 (图书, 视频, 图画): ";cin.ignore();getline(cin, type);library.queryByType(type);} else if (choice == 5) {library.displayAll();} else if (choice == 6) {int id;cout << "输入要编辑资料的ID: ";cin >> id;cout << "选择新分类: 1. 图书 2. 视频 3. 图画\n";int type;cin >> type;string title, author;int rating;cout << "输入新标题: ";cin.ignore();getline(cin, title);cout << "输入新作者: ";getline(cin, author);cout << "输入新评级 (0 未评级, 1 成人, 2 儿童): ";cin >> rating;if (type == 1) {string publisher, isbn;int pages;cout << "输入新的出版社: ";cin.ignore();getline(cin, publisher);cout << "输入新的ISBN: ";getline(cin, isbn);cout << "输入新的页数: ";cin >> pages;library.editMedia(id, new Book(id, title, author, static_cast<Rating>(rating), publisher, isbn, pages));} else if (type == 2) {string producer;int year, duration;cout << "输入新的作者: ";cin.ignore();getline(cin, producer);cout << "输入新的年份: ";cin >> year;cout << "输入新的持续时间（分钟）: ";cin >> duration;library.editMedia(id, new Video(id, title, author, static_cast<Rating>(rating), producer, year, duration));} else if (type == 3) {string nationality;int length, width;cout << "输入新国籍: ";cin.ignore();getline(cin, nationality);cout << "输入新长度（厘米）: ";cin >> length;cout << "输入新宽度（厘米）: ";cin >> width;library.editMedia(id, new Picture(id, title, author, static_cast<Rating>(rating), nationality, length, width));}} else if (choice == 7) {int id;cout << "输入要删除的资料ID: ";cin >> id;library.deleteMedia(id);} else if (choice == 8) {string filename;cout << "输入文件名: ";cin.ignore();getline(cin, filename);library.saveToFile(filename);} else if (choice == 9) {string filename;cout << "输入文件名: ";cin.ignore();getline(cin, filename);library.loadFromFile(filename);} else if (choice == 10) {library.countItems();} else if (choice == 11) {break;} else {cout << "无效的选择,请再试一次." << endl;}}return 0;
}