odbcdbgridfile.cpp

一个不错的数据源连接程序

// OdbcDBGridFILE.cpp: implementation of the COdbcDBGridFILE class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "demo2.h"
#include "OdbcDBGridFILE.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////


COdbcDBGridFILE::COdbcDBGridFILE(CGridCtrl *pGrid , CDatabase *pDatabase, CString strSql, CString strFilePath)
{
	m_pGrid = pGrid;
	m_pDatabase = pDatabase;
	m_strFilePath = strFilePath;
	m_strSql = strSql;
	
	m_hFile = NULL;
	m_hFilemap = NULL;
	m_pvFile = NULL;
	m_cpWrite = NULL;
	m_iCurrentCount = 1;

	m_iTotalCount = 0;
	m_pRowFileInfo = NULL;
	m_iMapFileSize = 8 * 1024 * 1024;
	m_iOnceReadRows = 500;
	m_iColumns = 0;

}

COdbcDBGridFILE::~COdbcDBGridFILE()
{

}


int COdbcDBGridFILE::GetSelectTotalCount()
{
	int iResult = 0;
	CString strValue = "";
	CString strSql = "select count(*) from ( "+ m_strSql + ") chensl";
	
	if(m_pDatabase == NULL)
	{
		AfxMessageBox("odbc dbgrid 中的数据库指针为空");
		return -1;
	}

	if(m_pDatabase->IsOpen() == FALSE)
	{
		AfxMessageBox("odbc dbgrid 中的数据库处于关闭状态");
		return -1;
	}

	m_Set.m_pDatabase = m_pDatabase;
	m_Set.Open(CRecordset::forwardOnly, (LPCTSTR)strSql);
	m_Set.GetFieldValue((short)0, strValue);
	m_Set.Close();
	iResult = atoi((LPCTSTR)strValue);
	
	return iResult;

}

int COdbcDBGridFILE::InitMapFile()
{
	int i = 0;
	m_pRowFileInfo = new SRowInfo[m_iTotalCount];
	if(m_pRowFileInfo == NULL)
	{
		AfxMessageBox("分配用于存储每行记录的信息的结构失败");
		
		return -1;
	}

	for(i = 0; i < m_iTotalCount; i++)
	{
		m_pRowFileInfo[i].bWritten = FALSE;
		m_pRowFileInfo[i].pAddress = NULL;
	}
	
	m_hFile = ::CreateFile((LPCTSTR)m_strFilePath, GENERIC_READ | GENERIC_WRITE ,
		0,NULL,CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL);
	if(m_hFile == INVALID_HANDLE_VALUE)
	{
		AfxMessageBox("创建文件失败");
		return -1;
	}

	m_hFilemap = ::CreateFileMapping(m_hFile, NULL, PAGE_READWRITE, 0, m_iMapFileSize, NULL);
	if(m_hFilemap == NULL)
	{
		AfxMessageBox("创建文件映射失败");
		::CloseHandle(m_hFile);
		return -1;
	}
	::CloseHandle(m_hFile);


	m_pvFile = ::MapViewOfFile(m_hFilemap,FILE_MAP_WRITE,0,0,0);
	if(m_pvFile == NULL)
	{
		AfxMessageBox("映射文件失败");
		::CloseHandle(m_hFilemap);
		::CloseHandle(m_hFile);
		return -1;
	}
	::CloseHandle(m_hFilemap);


	m_cpWrite = (char *)m_pvFile;
	return 0;	

}

int COdbcDBGridFILE::InitGrid()
{

	if(m_pGrid == NULL)
	{
		AfxMessageBox("发生错误，指向dbgrid控件的指针为空");
		return -1;
	}


	m_iTotalCount = GetSelectTotalCount();
	m_pGrid->SetVirtualMode(TRUE);
	m_pGrid->SetRowCount(m_iTotalCount + 1);
	m_pGrid->SetFixedRowCount(1);
	m_iColumns = this->GetSelectSqlColumns();
	if(m_Set.Open(CRecordset::forwardOnly, m_strSql) == 0)
	{
		AfxMessageBox("为查询语句打开记录集时失败");
		return -1;
	}
	
	m_pGrid->SetColumnCount(m_iColumns + 1);
	m_pGrid->SetFixedColumnCount(1);

	this->InitMapFile();
	
	return 0;

}

int COdbcDBGridFILE::FetchData()
{
	int i;
	CString strValue = "", strTemp = "";
	char cpTemp[2048];
	int iInitCount = m_iCurrentCount;
	while( (!m_Set.IsEOF()) && ((m_iCurrentCount - iInitCount) < m_iOnceReadRows))
	{
		strTemp = "";
		for(i = 0; i < m_iColumns; i++)
		{
			m_Set.GetFieldValue(i, strValue);
			if(strValue.GetLength() == 0)
			{
				strTemp = strTemp + "null,";
			}
			else
			{
				strTemp = strTemp + strValue + ",";
			}

		}
		sprintf(cpTemp, "%d=%s\r\n", m_iCurrentCount, (LPCTSTR)strTemp);

		m_pRowFileInfo[m_iCurrentCount - 1].bWritten = TRUE;
		m_pRowFileInfo[m_iCurrentCount - 1].pAddress = m_cpWrite;
		if(((int)(m_cpWrite - (char *)m_pvFile)) >= m_iMapFileSize - 500)
		{
		//	waitDlg.ShowWait("由于数据量很大,正在重新分配内存,请稍等....");
			return -1;
		}
		strcpy(m_cpWrite, cpTemp);
		m_cpWrite += strlen(cpTemp);
		m_iCurrentCount++;

		TRACE("the current rows is %d\r\n", m_iCurrentCount );
		m_Set.MoveNext();
	}

	*m_cpWrite = '\0';
	return 0;

}

int COdbcDBGridFILE::SetGridText(GV_DISPINFO *pDispInfo)
{
	CString strTemp = "", strText = "";
	if(pDispInfo->item.row == 0)//显示第一行的列名
	{
		if(pDispInfo->item.col > 0)
		{
			this->GetFieldInfo(pDispInfo->item.col - 1, strText);
			pDispInfo->item.strText = strText;
		}
	
	}
	else if(pDispInfo->item.col == 0)//显示行号
	{
		pDispInfo->item.strText.Format(_T("%d"),pDispInfo->item.row);
	}
	else 
	{
		if(GetAGridData(pDispInfo->item.row, pDispInfo->item.col, strText) == 0)
		{
			pDispInfo->item.strText = strText;
		}
		else
		{
			pDispInfo->item.strText = "";
			return -1;
			
		}
	}

	return 0;

}

int COdbcDBGridFILE::GetAGridData(int iRow, int iCol, CString &strOut)
{
	CString strTemp, strField;
	int iCount = 1, i = 0;
	char cpToken[] = ",";
	char *cpTemp1 = NULL, *cpTemp2 = NULL;
	char cpRow[1024];


	strTemp.Format("%d=", iRow);

	while(m_pRowFileInfo[iRow - 1].bWritten == FALSE)
	{
	//	waitDlg.ShowWait("正在获取数据,请稍等....");
	
		if(FetchData() != 0)
		{
			DealMapFileSizeLess();
			return -1;
		}
	}
//	waitDlg.ShowWindow(SW_HIDE);
	cpTemp2 = strstr(m_pRowFileInfo[iRow - 1].pAddress, "\r\n");
	if(cpTemp2)
	{
		cpTemp1 = m_pRowFileInfo[iRow - 1].pAddress + strTemp.GetLength();
		strncpy(cpRow, cpTemp1, (int)(cpTemp2 - cpTemp1));
		strcpy(cpRow + (int)(cpTemp2 - cpTemp1), "\0");
	
		char *cpResult = strtok(cpRow, cpToken);
		while(cpResult != NULL)
		{
			if(iCount == iCol)
			{
				strOut.Format("%s", cpResult);
				if(strOut == "null")
				{
					strOut = "";
				}
				break;
			}
			cpResult = strtok( NULL, cpToken );
			iCount++;
		}

	}

	return 0;

}

int COdbcDBGridFILE::Release()
{
	if(m_cpWrite != NULL)
	{
		m_cpWrite = NULL;
	}
	if(m_pRowFileInfo != NULL)
	{
		delete []m_pRowFileInfo; m_pRowFileInfo = NULL;
	}
	m_Set.Close();

	if(m_pvFile)
	{
		::UnmapViewOfFile(m_pvFile);
	}

	m_iCurrentCount = 1;
	return 0;


}

int COdbcDBGridFILE::DealMapFileSizeLess()
{
	m_iMapFileSize += 10 * 1024 * 1024;
	m_pGrid->DeleteAllItems();
	this->Release();
	this->InitGrid();
//	waitDlg.ShowWindow(SW_HIDE);
	return 0;

}

int COdbcDBGridFILE::GetSelectSqlColumns()
{
	int i = 0;
	CString strValue = "";

	if(m_pDatabase == NULL)
	{
		AfxMessageBox("odbc dbgrid 中的数据库指针为空");
		return -1;
	}

	if(m_pDatabase->IsOpen() == FALSE)
	{
		AfxMessageBox("odbc dbgrid 中的数据库处于关闭状态");
		return -1;
	}

	m_Set.m_pDatabase = m_pDatabase;
	m_Set.Open(CRecordset::forwardOnly, (LPCTSTR)m_strSql);
	try
	{
		for(i = 0; i < 500; i++)
		{
			m_Set.GetFieldValue((short)i, strValue);
		}
	}
	catch(CDBException *e)
	{
		m_Set.Close();
		if(e->m_nRetCode == AFX_SQL_ERROR_FIELD_NOT_FOUND)
		{
			e->Delete();
			return i;
		}
		else
		{
			e->ReportError();
			e->Delete();
			return -1;
		}
	}


	return -1;

}

int COdbcDBGridFILE::GetFieldInfo(int iFieldIndex, CString &strFieldName)
{
	CODBCFieldInfo info;
	m_Set.GetODBCFieldInfo((short)iFieldIndex, info);
	strFieldName = info.m_strName;

	return 0;

}