Qt浅谈之二十一log调试日志
Posted jhcelue
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一、简单介绍
近期因调试code时，想了解程序的流程，但苦于没有一个简易的日志记录，不停使用qDebug打印输出，而终于提交代码时得去多次删除信息打印，有时还会出现新改动的代码分不清是哪些部分。而使用#ifdef _DEBUG又比較烦这套，因此写了些简单的日志，方便排除问题，临时不能用于多线程中，以后须要再补充。
二、具体解释
1、追踪函数
#ifdef _DEBUG_PRINT
#define DEBUGPRINT DEBUGInfo printinfo(__FILE__, __LINE__, __FUNCTION__);
#else
#define DEBUGPRINT
#endif
class DEBUGInfo
{
public:
DEBUGInfo(QString file, int line, QString func);
~DEBUGInfo();
private:
QString fileName;
int fileLine;
QString funcName;
};DEBUGInfo::DEBUGInfo(QString file, int line, QString func)
:fileName(file)
,fileLine(line)
,funcName(func)
{
QString result = "";
QString beginTime = QDateTime::currentDateTime().toString("[yyyy-dd-MM hh:mm:ss.zzz] ");
result += beginTime + "Enter:{" + fileName + ":" + QString::number(fileLine) + "---" + funcName + "}";
qDebug() << result.toStdString().c_str();
}
DEBUGInfo::~DEBUGInfo()
{
QString result = "";
QString beginTime = QDateTime::currentDateTime().toString("[yyyy-dd-MM hh:mm:ss.zzz] ");
result += beginTime + "Leave:{" + fileName + ":" + QString::number(fileLine) + "---" + funcName + "}";
qDebug() << result.toStdString().c_str();
}
使用：在须要查看的函数中增加DEBUGPRINT就可以。输出文件名称，所在的行和函数名字。
void HelloWorld()
{
DEBUGPRINT
}
2、信息打印和写日志文件
enum LOGLEVEL{
LOG_DEBUG = 0, /**< Debug >**/
LOG_INFO, /**< Info >**/
LOG_WARN, /**< Warn >**/
LOG_ERROR /**< Error >**/
};
class LogWriter{
public:
static LogWriter* getLogCenter();
void PrintLog(LOGLEVEL level, const char* msg, ...);
void SaveFileLog(LOGLEVEL level, const char* msg, ...);
void setLogPath(QString logPath); //defalut: current path
void setLogLevel(LOGLEVEL logLevel); //defalut: LOG_DEBUG
private:
static LogWriter * _logCenter;
explicit LogWriter();
~LogWriter();
private:
QString _logPath;
LOGLEVEL _logLevel;
private:
QString getLevelStr(LOGLEVEL level);
};LogWriter *LogWriter::getLogCenter()
{
if (_logCenter == NULL)
_logCenter = new LogWriter;
return _logCenter;
}
LogWriter::LogWriter()
{
_logLevel = LOG_DEBUG;
_logPath = QDir::currentPath();
}
LogWriter::~LogWriter()
{
if (_logCenter) {
delete _logCenter;
_logCenter = NULL;
}
}
void LogWriter::PrintLog(LOGLEVEL level, const char *msg, ...)
{
if (level < _logLevel) return; //low level
char logBuffer[8192] = {0};
va_list vl_fmt; //buffer
va_start(vl_fmt, msg);
vsprintf(logBuffer, msg, vl_fmt);
va_end(vl_fmt);
QString fileTime = "";
QString logTime = "";
QString logLevel = getLevelStr(level);
fileTime = QDateTime::currentDateTime().toString("yyyyddMM");
logTime = QDateTime::currentDateTime().toString("yyyy-dd-MM hh:mm:ss.zzz");
qDebug("[%s] [%s] {%s}", logTime.toStdString().c_str(), logLevel.toStdString().c_str(), logBuffer);
}
void LogWriter::SaveFileLog(LOGLEVEL level, const char *msg, ...)
{
if (level < _logLevel) return; //low level
char logBuffer[8192] = {0};
va_list vl_fmt; //buff
va_start(vl_fmt, msg);
vsprintf(logBuffer, msg, vl_fmt);
va_end(vl_fmt);
QString logTime = "";
QString fileTime = "";
fileTime = QDateTime::currentDateTime().toString("yyyyddMM");
logTime = QDateTime::currentDateTime().toString("[yyyy-dd-MM hh:mm:ss.zzz]");
QString logLevel = getLevelStr(level);
QString logFile = _logPath;
if (logFile.right(1) != "/") {
logFile += "/";
}
QDir mDir(logFile);
if (!mDir.exists()) {
mDir.mkpath(logFile);
}
logFile += "isoft_";
logFile += fileTime;
logFile += ".log";
QFile file(logFile);
file.open(QIODevice::ReadWrite | QIODevice::Append | QIODevice::Text);
QTextStream out(&file);
out << logTime << " [" << logLevel << "] " << "{" << logBuffer << "}" << endl;
file.close();
}
QString LogWriter::getLevelStr(LOGLEVEL level)
{
switch(level) {
case LOG_DEBUG: return "LOG_DEBUG"; break;
case LOG_INFO: return "LOG_INFO"; break;
case LOG_WARN: return "LOG_WARN"; break;
case LOG_ERROR: return "LOG_ERROR"; break;
}
}
void LogWriter::setLogPath(QString logPath)
{
_logPath = logPath;
}
void LogWriter::setLogLevel(LOGLEVEL logLevel)
{
_logLevel = logLevel;
}能够设置日志的级别和日志文件的路径。
在函数中使用：
LogWriter::getLogCenter()->PrintLog(LOG_DEBUG, "hello world"); LogWriter::getLogCenter()->PrintLog(LOG_INFO, "%s:%s,%d", "hello", "world", 1234); LogWriter::getLogCenter()->SaveFileLog(LOG_WARN, "hello world"); LogWriter::getLogCenter()->SaveFileLog(LOG_ERROR, "%s:%s,%d", "hello", "world", 1234);
也会在当前路径下生成文件。
3、Qt自带样例
Qt官方样例： #include <qapplication.h>
#include <stdio.h>
#include <stdlib.h>
void myMessageOutput(QtMsgType type, const char *msg)
{
switch (type) {
case QtDebugMsg:
fprintf(stderr, "Debug: %s\n", msg);
break;
case QtWarningMsg:
fprintf(stderr, "Warning: %s\n", msg);
break;
case QtCriticalMsg:
fprintf(stderr, "Critical: %s\n", msg);
break;
case QtFatalMsg:
fprintf(stderr, "Fatal: %s\n", msg);
abort();
}
}
int main(int argc, char **argv)
{
qInstallMsgHandler(myMessageOutput);
QApplication app(argc, argv);
...
return app.exec();
}自己定义改动：void outputMessage(QtMsgType type, const char *msg)
{
static QMutex mutex;
mutex.lock();
QString text;
switch(type)
{
case QtDebugMsg:
text = QString("Debug:");
break;
case QtWarningMsg:
text = QString("Warning:");
break;
case QtCriticalMsg:
text = QString("Critical:");
break;
case QtFatalMsg:
text = QString("Fatal:");
abort();
}
QString message = QString("[%1] %2 %3").arg(QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss ddd")).arg(text).arg(msg);
QFile file("log.txt");
file.open(QIODevice::WriteOnly | QIODevice::Append);
QTextStream text_stream(&file);
text_stream << message << endl;
file.flush();
file.close();
mutex.unlock();
}qInstallMsgHandler(outputMessage);
qWarning("This is a warning message");
qCritical("This is a critical message");
//qInstallMsgHandler(0) //To restore the message handler, call执行结果：
三、总结
（1）本文仅仅是一个简单的日志记录。还能够设计成异步的多线程式的，甚至能够增加到线程池，对性能要求较高的系统还得考虑文件的大小控制、存储空间的控制、文件的级别控制、文件的日期控制和自己主动清除等操作。（2）本人思路有限，若有更好的设计建议。也可发邮件沟通，在此先感谢。邮箱地址[email protected]。
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