参照《重构-改善既有代码的设计》书中关于不良设计（违反SOLID）、不良代码（代码坏味道bad smells）的判别标准进行重构void Library::filemanage() { fstream f; string s; f.open("books.txt", ios::out); addBook(); for (int i = 0; i < books.size(); i++) { f << books[i]->getName() << " " << books[i]->getAuther() << " " << books[i]->getNum() << " " << books[i]->getinstock() << endl; } f.close(); cout << "输入成功" << endl; } void Library::open() { fstream f; f.open("books.txt", ios::in); string name; string auther; string number; int instock; while (f >> name >> auther >> number >> instock) { cout << name << " " << auther << " " << number << " " << instock << endl; int i; for (i = 0; i < books.size(); i++) { if (books[i]->getNum() == number) { books[i]->setname(name); books[i]->setauther(auther); books[i]->setnum(number); books[i]->set(instock); } } } f.close(); cout << "输出成功" << endl; system("pause"); system("cls"); }

以下一个可能的重构方案：

1. 单一职责原则：将文件读写和书籍管理分离成两个类，`FileManager` 和 `BookManager`。

class FileManager {
public:
    virtual ~FileManager() {}
    virtual void write(const std::string& filename, const std::vector<std::string>& lines) = 0;
    virtual std::vector<std::string> read(const std::string& filename) = 0;
};

class BookManager {
public:
    virtual ~BookManager() {}
    virtual bool addBook(const std::string& name, const std::string& author, const std::string& num, int instock) = 0;
    virtual std::vector<Book*> getBooks() = 0;
};

2. 依赖倒置原则：将 `Library` 类中的文件读写操作抽象成 `FileManager` 接口，并将其作为 `Library` 的构造函数参数传入。

class Library {
public:
    Library(FileManager* fileManager, BookManager* bookManager);
    bool addBook(const std::string& name, const std::string& author, const std::string& num, int instock);
    void printBooks();
private:
    FileManager* fileManager_;
    BookManager* bookManager_;
};

3. 开闭原则：使用工厂模式来创建 `Book` 对象，以便将来添加或删除书籍信息的属性时不需要修改 `Book` 类。

class BookFactory {
public:
    static Book* create(const std::string& name, const std::string& author, const std::string& num, int instock);
};

4. 代码坏味道：将文件读写操作抽象成独立的函数，并将其封装在 `FileManager` 类中。

class TextFileManager : public FileManager {
public:
    void write(const std::string& filename, const std::vector<std::string>& lines) override;
    std::vector<std::string> read(const std::string& filename) override;
};

void TextFileManager::write(const std::string& filename, const std::vector<std::string>& lines) {
    std::ofstream f(filename);
    for (const auto& line : lines) {
        f << line << std::endl;
    }
}

std::vector<std::string> TextFileManager::read(const std::string& filename) {
    std::ifstream f(filename);
    std::vector<std::string> lines;
    std::string line;
    while (std::getline(f, line)) {
        lines.push_back(line);
    }
    return lines;
}

重构后的 `Library` 类中的 `addBook()` 和 `printBooks()` 函数的实现如下：

bool Library::addBook(const std::string& name, const std::string& author, const std::string& num, int instock) {
    bool success = bookManager_->addBook(name, author, num, instock);
    if (success) {
        std::vector<std::string> lines;
        for (const auto& book : bookManager_->getBooks()) {
            lines.push_back(book->getName() + " " + book->getAuthor() + " " + book->getNum() + " " + std::to_string(book->getInstock()));
        }
        fileManager_->write("books.txt", lines);
    }
    return success;
}

void Library::printBooks() {
    std::vector<std::string> lines = fileManager_->read("books.txt");
    for (const auto& line : lines) {
        std::istringstream iss(line);
        std::string name, author, num;
        int instock;
        iss >> name >> author >> num >> instock;
        std::cout << name << " " << author << " " << num << " " << instock << std::endl;
    }
}