c++实现日志类(写入logfile)

#include <iostream>
#include <fstream>
#include <sstream>
#include <ctime>
enum MyLogLevel {
    LOG_INFO,
    LOG_DBG,
    LOG_WARNING,
    LOG_ERROR,
    LOG_CRITICAL
};

class MyLogger {
public:
    static MyLogger& GetInstance(MyLogLevel level = LOG_INFO) {
        static MyLogger instance(level);
        return instance;
    }

    MyLogger(MyLogger const&) = delete;
    void operator=(MyLogger const&) = delete;

    template<typename... Args>
    void Log(MyLogLevel level, const std::string& format, Args... args) {
        if (level >= level_) {
            std::time_t now = std::time(nullptr);
            char time_str[20];
            std::strftime(time_str, sizeof(time_str), "%Y-%m-%d %H:%M:%S", std::localtime(&now));
            file_ << "[" << time_str << "] ";
            switch (level) {
                case LOG_INFO:
                    file_ << "[INFO] ";
                    break;
                case LOG_DBG:
                    file_ << "[DEBUG] ";
                    break;
                case LOG_WARNING:
                    file_ << "[WARNING] ";
                    break;
                case LOG_ERROR:
                    file_ << "[ERROR] ";
                    break;
                case LOG_CRITICAL:
                    file_ << "[CRITICAL] ";
                    break;
            }
            std::stringstream ss;
            ss << format;
            log_impl(ss, args...);
            file_ << ss.str() << std::endl;
        }
    }

    void SetLevel(MyLogLevel level) {
        level_ = level;
    }

private:
    MyLogger(MyLogLevel level) : level_(level) {
        file_.open("main.log", std::ios::out | std::ios::app);
    }

    ~MyLogger() {
        file_.close();
    }

    template<typename T, typename... Args>
    void log_impl(std::stringstream& ss, T value, Args... args) {
        ss << value;
        log_impl(ss, args...);
    }

    void log_impl(std::stringstream& ss) {}

    MyLogLevel level_;
    std::ofstream file_;
};

使用

MyLogger& logger = MyLogger::GetInstance(LOG_WARNING);
logger.Log(LOG_INFO, __FILE__, " " , __LINE__, " ", "hello world");