QT日誌輸出到文件(UTF-8格式)

void outputMessage(QtMsgType type, const QMessageLogContext &context, const QString &msg)
{
    QString filename;
    static QMutex mutex;
    int index;

    mutex.lock();
    QString text;

    switch(type)
    {

    case QtDebugMsg:
        text = QString("<<Debug>>");
        break;
    case QtInfoMsg:
        text = QString("<<Info>>");
        break;
    case QtWarningMsg:
        text = QString("<<Warning>>");
        break;

    case QtCriticalMsg:
        text = QString("<<Critical>>");
        break;

    case QtFatalMsg:
        text = QString("<<Fatal>>");
        break;
    }

    index =QString(context.file).length() - QString(context.file).lastIndexOf('\\') - 1;
    filename = QString(context.file).right(index);
    QString context_info = QString("[(%1)%2]").arg(filename).arg(context.line);
    QString current_date_time = QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss");
    QString current_date = QString("%1").arg(current_date_time);
    QString message = QString("%1 %2 %3 %4").arg(current_date).arg(text).arg(context_info).arg(msg);

    QFile file("log.txt");
    file.open(QIODevice::WriteOnly | QIODevice::Append);
    QTextStream text_stream(&file);
    text_stream.setCodec("utf-8");
    text_stream << message;

    file.flush();
    file.close();

    mutex.unlock();
}