QT重定向qDeubg到文件

1.重写outputMessage函数

void outputMessage(QtMsgType type, const QMessageLogContext& context, const QString& msg)
{
    Q_UNUSED(type)
    Q_UNUSED(context)
    static QMutex mutex(QMutex::Recursive);
    mutex.lock ();

    QString currentDateTime = QDateTime::currentDateTime().toString("yyyy-MM-dd HH:mm:ss:");
    QString message = QString("%1 %2").arg (currentDateTime).arg (msg);
    QFile file("log.txt");
    file.open (QIODevice::WriteOnly | QIODevice::Append | QIODevice::Text);

    QTextStream stream(&file);
    stream << message << endl;
    file.flush();
    file.close();
    mutex.unlock();
}

2.注册消息句柄
qInstallMessageHandler(outputMessage);