如何自定义Boost.Log的“TimeStamp”格式

我想得到年-月-日时：分：秒.分数（2位数字），如果我使用“%Y-%m-%d %H:%M:%S.%f”，我几乎得到了什么我想要秒的小数部分（最后一部分）例外，它在我的 Windows XP 上显示 6 位数字，我不知道如何只获取 2 位数字，知道吗？

我正在用这个

namespace boost
{
    BOOST_LOG_OPEN_NAMESPACE

    namespace attributes
    {
        template <typename date_time_type>
        void format_time_ms( std::ostringstream& formatter, const date_time_type& date_time)
        {
            auto time = date_time.time_of_day();
            using namespace std;
            formatter
                << setfill( '0') << setw( 2) << time.hours()   << ':'
                << setfill( '0') << setw( 2) << time.minutes() << ':'
                << setfill( '0') << setw( 2) << time.seconds() << ','
                << setfill( '0') << setw( 3) << time.fractional_seconds() / 1000;
        }

        template <typename date_time_type>
        std::string format_time_ms( const date_time_type& date_time)
        {
            std::ostringstream formatter;
            format_time_ms( formatter, date_time);
            auto time = date_time.time_of_day();
            return formatter.str();
        }

        template <typename date_time_type>
        std::string format_date_time_ms( const date_time_type& date_time, const char date_time_sep = ' ')
        {
            using namespace std;
            ostringstream formatter;
            auto date = date_time.date();
            formatter
                << date.year() << '-'
                << setfill( '0') << setw( 2) << int( date.month()) << '-'
                << setfill( '0') << setw( 2) << date.day() << date_time_sep;
            format_time_ms( formatter, date_time);
            return formatter.str();
        }

        template <typename date_time_type, const char date_time_sep = ' '>
        struct date_time_ms_formatter
        {           
            std::string operator () ( const date_time_type& date_time) { return format_date_time_ms( date_time, date_time_sep); }
        };

        struct time_ms_formatter
        {
            template <typename date_time_type>
            std::string operator () ( const date_time_type& date_time) { return format_time_ms( date_time); }
        };

        template <typename time_type>
        struct local_clock_source
        {
            time_type operator () () const
            {
                return date_time::microsec_clock<time_type>::local_time();
            }
        };

        template <typename time_type>
        struct universal_clock_source
        {
            time_type operator () () const
            {
                return date_time::microsec_clock<time_type>::universal_time();
            }
        };

        template <typename time_type, typename clock_source_type, typename formater_type>
        class custom_clock: public attribute
        {
        public:
            class impl: public attribute::impl
            {
            public:
                attribute_value get_value()
                {
                    auto str = formater_type()( clock_source_type()());
                    return make_attribute_value( str);
                }
            };

            custom_clock(): attribute( new impl()) {}

            explicit custom_clock( const cast_source& source): attribute( source.as<impl>()) {}
        };


        typedef custom_clock<boost::posix_time::ptime, local_clock_source<boost::posix_time::ptime>, date_time_ms_formatter<boost::posix_time::ptime, '\t'> >       local_date_time_ms_clock;
        typedef custom_clock<boost::posix_time::ptime, universal_clock_source<boost::posix_time::ptime>, date_time_ms_formatter<boost::posix_time::ptime, '\t'> >   universal_date_time_ms_clock;

        typedef custom_clock<boost::posix_time::ptime, local_clock_source<boost::posix_time::ptime>, time_ms_formatter>     local_time_ms_clock;
        typedef custom_clock<boost::posix_time::ptime, universal_clock_source<boost::posix_time::ptime>, time_ms_formatter> universal_time_ms_clock;
    }

    BOOST_LOG_CLOSE_NAMESPACE // namespace log
}

初始化为

BOOST_LOG_ATTRIBUTE_KEYWORD( dateTimeStamp,     "DateTime",     boost::posix_time::ptime)
BOOST_LOG_ATTRIBUTE_KEYWORD( timeStamp,         "Time",         boost::posix_time::ptime)

core->add_global_attribute( dateTimeStamp.get_name(),   attrs::local_date_time_ms_clock());
core->add_global_attribute( timeStamp.get_name(),       attrs::local_time_ms_clock());

并用作

expr::stream << expr::attr<std::string>( dateTimeStamp.get_name())
expr::stream << expr::attr<std::string>( timeStamp.get_name())