loghndlr.cpp

设计模式之singleton模式例程

// LogHndlr.cpp - Implementation of CLogHndlr class

// CLogHndlr is derived from CMsgHndlr and it is responsible for logging the message on to 
// the log file, when HandleMessage method is called

// Written by : T. Kulathu Sarma

// This file is part of Singleton application to demonstrate the concept of Singleton classes.
// This file is provided "as is" with no expressed or implied warranty.

#include "stdafx.h"
#include "LogHndlr.h"
#include <io.h>
#include "MsgHndlrReg.h"

// Register CLogHndlr agent in the message handler registry
static CMsgHndlrRegistry< CLogHndlr > gLogHndlr( RUNTIME_CLASS( CLogHndlr ), "LOGHNDLR" );

IMPLEMENT_DYNCREATE( CLogHndlr, CMsgHndlr )

// CLogHndlr - Implementation

CLogHndlr::CLogHndlr()
{
	// Step 1 - Initialize class members
	m_csLogFile = "TEST.LOG";
}

CLogHndlr::~CLogHndlr()
{
}

INT CLogHndlr::SetLogFile( LPCSTR lpszLogFile )
{
	// Step 1 - If log file is present, remove it
	if( _access( lpszLogFile, 00 ) != -1 )
	{
		DeleteFile( lpszLogFile );
	}
	// Step 2 - Set m_csLogFile to the parameter passed
	m_csLogFile = lpszLogFile;
	return SUCCESS;
}

INT CLogHndlr::GetLogFile( CString & rcsLogFile )
{
	// Step 1 - Set m_csLogFile to the parameter passed
	rcsLogFile = m_csLogFile;
	return SUCCESS;
}

// HandleMessage logs the message to the given log file
// It displays the message to the user after logging it to the file
// Application data is ignored in this method
INT CLogHndlr::HandleMessage( LPCSTR lpszMessage, INT nType, DWORD /* dwAppData */ )
{
	INT nIcon = 0;

	// Step 1 - Check, if log file name is provided
	if( m_csLogFile.IsEmpty() == TRUE )
	{
		return FAILURE;
	}

	// Step 2 - Open the log file in append mode
	FILE * pFPtr = fopen( m_csLogFile, "a+" );
	if( pFPtr == NULL )
	{
		return FAILURE;
	}

	// Step 3 - Write the message to the log file
	if( nType == INFO_TYPE )
	{
		fprintf( pFPtr, "Information : " );
		nIcon = MB_ICONINFORMATION;
	}
	else if( nType == WARNING_TYPE )
	{
		fprintf( pFPtr, "Warning : " );
		nIcon = MB_ICONEXCLAMATION;
	}
	else if( nType == ERROR_TYPE )
	{
		fprintf( pFPtr, "Error : " );
		nIcon = MB_ICONSTOP;
	}
	fprintf( pFPtr, "%s\n", lpszMessage );

	// Step 4 - Close the file
	fclose( pFPtr );

	// Step 5 - Display the message using AfxMessageBox with appropriate icons
	AfxMessageBox( CString( "Log Message Handler : " ) + lpszMessage, MB_OK | nIcon );

	return SUCCESS;
}