visual C++实现为win32动态库运用debugview输出日志1:使用单例模式实现CLog类

本文介绍了一个基于Win32的C++日志类实现，该类采用单例模式，确保了全局唯一实例。日志类通过WaitForSingleObject和ReleaseMutex进行线程同步，避免了多线程环境下写入日志的竞争条件。

win32动态库比MFC动态库使用更广泛：

/************************************************************************
*　功能描述：日志类.
*　其它说明：使用单例模式实现
************************************************************************/
#ifndef _LOG_
#define _LOG_

#include "../MptBase.h"

class MPTEXPORT CLog
{
public:
	static CLog *m_plog;
	//static CMutex *m_mutex;
	static HANDLE m_mutex;
private:

#if 0
	FILE * m_fp;
	void WriteLog(const CString &str, ...);
#endif

private:
	CLog(void);

public:
	static CLog *GetInstance();
	void WriteLog(const LPCTSTR str, ...);
	
	~CLog(void);	
};

#endif

#include "stdafx.h"
#include "Log.h"
#include "debugviewhelper.h"
#include <tchar.h>


#if 0
static CString GetCurrentPath()
{
	TCHAR path[MAX_PATH] = {0};
	GetModuleFileName(GetModuleHandle(NULL), path, MAX_PATH);
	CString str = path;
	int nlen = str.ReverseFind('\\');
	str = str.Left(nlen);
	if (str.Right(0) != _T("\\"))
		str = str + _T("\\");
	return str;
}
#endif

CLog::CLog(void)
{
#if 0
	CString str = GetCurrentPath();
	str += _T("log.txt");	
	m_fp = _tfsopen((LPCTSTR)str, _T("w+, ccs=UTF-8"), _SH_DENYNO);
#endif
}

CLog *CLog::m_plog = NULL;
HANDLE CLog::m_mutex = CreateMutexA(NULL, FALSE, "mutex");//new CMutex();

CLog::~CLog(void)
{
	if (m_mutex != NULL)
	{
		//delete m_mutex;
		CloseHandle(m_mutex);
		m_mutex = NULL;
	}

	if (m_plog != NULL)
	{
		delete m_plog;
		m_plog = NULL;
	}
}

CLog * CLog::GetInstance()
{
	if (m_plog != NULL)
	{
		return m_plog;
	}
	else
	{
		 //m_mutex->Lock();
		WaitForSingleObject(m_mutex, INFINITE);
		 if (m_plog == NULL)
		 {
			 m_plog = new CLog();		 
		 }
		 //m_mutex->Unlock();
		 ReleaseMutex(m_mutex);
		 return m_plog;
	}
}

void CLog::WriteLog(const LPCTSTR str, ...)
{
	if((_tcslen(str) == 0))
		return;

	TCHAR buffer[1024];
	memset(buffer, 0, sizeof(buffer));

	TCHAR logtext[64+1024] = {0};
	swprintf(logtext, _T("%d "), GetCurrentThreadId());
	size_t textOffset = wcslen(logtext);

	va_list maker;	
	va_start(maker, str);
	_vsntprintf_s(buffer, sizeof(buffer)/sizeof(TCHAR) - 1, str, maker);
	va_end(maker);

	//DI << buffer;
	wcscat(logtext, buffer);
	DI << logtext;
}

#if 0
void CLog::WriteLog(const CString &str, ...)
{

	if(!m_fp || (_tcslen(str)== 0))
		return;

	TCHAR buffer[1024];
	va_list maker;

	va_start(maker, str);
	_vsntprintf_s(buffer, sizeof(str)/sizeof(TCHAR) - 1, 1024, str, maker);
	va_end(maker);

	CTime tm = CTime::GetCurrentTime();

	_ftprintf_s(m_fp, _T("%4d-%02d-%02d %02d:%02d:%02d %s\r\n"), 
		tm.GetYear(),
		tm.GetMonth(),
		tm.GetDay(),
		tm.GetHour(),
		tm.GetMinute(),
		tm.GetSecond(), 
		buffer);
	fflush(m_fp);
}
#endif