c++怎么实现一个简单的日志系统_c++日志系统设计与实现思路

enum class LogLevel {
    DEBUG,
    INFO,
    WARNING,
    ERROR
};

class Logger {
public:
    explicit Logger(LogLevel level = LogLevel::DEBUG) : currentLevel(level) {}

    void SetLogLevel(LogLevel level) {
        currentLevel = level;
    }

    void Log(LogLevel level, const std::string& msg) {
        if (level < currentLevel) return;

        std::ostringstream oss;
        oss << GetCurrentTime() << " [" << LevelToString(level) << "] " << msg << std::endl;
        std::cout << oss.str(); // 同时输出到控制台
        WriteToFile(oss.str()); // 可选：写入文件
    }

    void Debug(const std::string& msg) { Log(LogLevel::DEBUG, msg); }
    void Info(const std::string& msg)  { Log(LogLevel::INFO,  msg); }
    void Warning(const std::string& msg) { Log(LogLevel::WARNING, msg); }
    void Error(const std::string& msg)   { Log(LogLevel::ERROR,   msg); }

private:
    LogLevel currentLevel;

    std::string GetCurrentTime() {
        auto now = std::chrono::system_clock::now();
        auto time_t = std::chrono::system_clock::to_time_t(now);
        std::stringstream ss;
        ss << std::put_time(std::localtime(&time_t), "%Y-%m-%d %H:%M:%S");
        return ss.str();
    }

    std::string LevelToString(LogLevel level) {
        switch (level) {
            case LogLevel::DEBUG:   return "DEBUG";
            case LogLevel::INFO:    return "INFO";
            case LogLevel::WARNING: return "WARN";
            case LogLevel::ERROR:   return "ERROR";
            default:                return "UNKNOWN";
        }
    }

    void WriteToFile(const std::string& line) {
        static std::ofstream file("app.log", std::ios::app);
        if (file.is_open()) {
            file << line;
            file.flush(); // 立即写入磁盘
        }
    }
};

Logger g_Logger(LogLevel::DEBUG); // 全局日志对象

g_Logger.Info("程序启动成功");
g_Logger.Warning("资源加载较慢");
g_Logger.Error("无法打开配置文件");