qDebug日志写入本地文件

Published: at 02:11 AM | 2 min read

在Qt中使用qDebug打印日志信息是非常方便的，它可以直接打印Qt提供的复杂数据结构，如:QStringList,QVariantMap等。不做处理的话它只能在编辑器中打印调试信息，下面介绍将日志信息写入文件的实现方法。

static struct LogWrap {
	LogWrap::LogWrap() { reset(); }
	LogWrap::~LogWrap() { reset(); }
	void reset() {
		isInit = false;
		level = "";
		date = "";
		if (ts) {
			delete ts;
			ts = nullptr;
		}
		if (file) {
			delete file;
			file = nullptr;
		}
	}
	bool isInit;
	QMutex locker;
	QString level;
	QString date;
	QFile *file;
	QTextStream *ts;
} s_logWrap;

#define _TIME_ qPrintable(QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss.zzz"))
QStringList s_outputFileNames = QStringList() << "view.cpp" << "store.cpp";
void myMessageOutput(QtMsgType type, const QMessageLogContext &context, const QString &msg)
{
	bool isFilter = true;
	QString file(context.file);
	for (auto iter = s_outputFileNames.begin(); iter != s_outputFileNames.end(); ++iter) {
		if (file.contains(*iter)) {
			isFilter = false;
			break;
		}
	}
	if (isFilter) {
		return;
	}

	QString formatMsg;
	switch (type) {
	case QtDebugMsg:
		formatMsg = "Debug:" + msg;
		break;
	case QtWarningMsg:
		formatMsg = "Warning:" + msg;
		break;
	case QtCriticalMsg:
		formatMsg = "Critical:" + msg;
		break;
	case QtFatalMsg:
		formatMsg = "Fatal:" + msg;
		break;
	default:
		return;
	}

	QString curDate = QDate::currentDate().toString("yyyyMMdd");
	if (curDate != s_logWrap.date) {
		s_logWrap.reset();
	}

	if (!s_logWrap.isInit) {
		s_logWrap.isInit = true;
		QDir().mkpath("log");
		s_logWrap.level = "debug";
		s_logWrap.date = QDate::currentDate().toString("yyyyMMdd");
		s_logWrap.file = new QFile(QString("log\\log%1.log").arg(s_logWrap.date));
		if (s_logWrap.file->open(QIODevice::WriteOnly | QIODevice::Append)) {
			s_logWrap.ts = new QTextStream(s_logWrap.file);
		}
	}

	if (s_logWrap.ts) {
		QString text = _TIME_ + QString("[%1:%2]%3\n").arg(context.file).arg(context.line).arg(formatMsg);
		OutputDebugString(text.toStdWString().c_str());
		QMutexLocker locker(&s_logWrap.locker);
		(*s_logWrap.ts << text).flush();
	}
}

在Application创建之前调用：

qInstallMessageHandler(myMessageOutput);