C++中如何使用RAII管理资源_资源获取即初始化

#include <iostream>
#include <fstream>
#include <memory>

class FileHandler {
private:
    std::ofstream file;
    std::string filename;

public:
    // 构造函数：获取资源
    FileHandler(const std::string& filename) : filename(filename), file(filename) {
        if (!file.is_open()) {
            throw std::runtime_error("Could not open file: " + filename);
        }
        std::cout << "File " << filename << " opened." << std::endl;
    }

    // 析构函数：释放资源
    ~FileHandler() {
        if (file.is_open()) {
            file.close();
            std::cout << "File " << filename << " closed." << std::endl;
        }
    }

    // 阻止拷贝构造
    FileHandler(const FileHandler&) = delete;
    FileHandler& operator=(const FileHandler&) = delete;

    // 移动构造
    FileHandler(FileHandler&& other) noexcept : file(std::move(other.file)), filename(std::move(other.filename)) {
        std::cout << "FileHandler move constructor called." << std::endl;
    }

    FileHandler& operator=(FileHandler&& other) noexcept {
        if (this != &other) {
            file = std::move(other.file);
            filename = std::move(other.filename);
        }
        std::cout << "FileHandler move assignment called." << std::endl;
        return *this;
    }


    void write_data(const std::string& data) {
        file << data << std::endl;
    }
};

int main() {
    try {
        FileHandler my_file("example.txt");
        my_file.write_data("Hello, RAII!");
        // 文件会在 my_file 对象离开作用域时自动关闭
    } catch (const std::exception& e) {
        std::cerr << "Exception: " << e.what() << std::endl;
        return 1;
    }

    std::cout << "Program finished." << std::endl;
    return 0;
}