功能:
需要将多种格式的文件保存到SQL server数据库中,例如:.dxf/bmp/jpg/doc等等。
在需要时,将保存的文件从数据库中读取回来,并按照原来格式写回到本地硬盘上,供程序使用。参照http://community.csdn.net/Expert/FAQ/FAQ_Index.asp?id=18143的例子改写。
在SQL Server 2K中将文件数据的字段设置为image类型。问题:
已经将文件写入数据库中,但是读取文件后,文件大小与原文件一致,但是里面数据却不正常。
需要将多种格式的文件保存到SQL server数据库中,例如:.dxf/bmp/jpg/doc等等。
在需要时,将保存的文件从数据库中读取回来,并按照原来格式写回到本地硬盘上,供程序使用。参照http://community.csdn.net/Expert/FAQ/FAQ_Index.asp?id=18143的例子改写。
在SQL Server 2K中将文件数据的字段设置为image类型。问题:
已经将文件写入数据库中,但是读取文件后,文件大小与原文件一致,但是里面数据却不正常。
CString fileName="ASPHALT.bmp";
_bstr_t strCnn("Driver={SQL Server};Server=127.0.0.1;Database=subway;Uid=subway_admin;Pwd=admin;"); CFile imagefile;
if(0 == imagefile.Open(fileName,CFile::modeRead))
return;
_RecordsetPtr pRs = NULL;
_ConnectionPtr pConnection = NULL;
_variant_t varChunk;
HRESULT hr;
BYTE* pbuf;
long nLength = imagefile.GetLength();
pbuf = new BYTE[nLength+2];
if(pbuf == NULL)
return; //allocate memory error; imagefile.Read(pbuf,nLength); //read the file into memory
BYTE *pBufEx;
pBufEx = pbuf;
//build a SAFFERRAY
SAFEARRAY* psa;
SAFEARRAYBOUND rgsabound[1];
rgsabound[0].lLbound = 0;
rgsabound[0].cElements = nLength;
psa = SafeArrayCreate(VT_UI1, 1, rgsabound); for (long i = 0; i < nLength; i++)
SafeArrayPutElement (psa, &i, pBufEx++);
VARIANT varBLOB;
varBLOB.vt = VT_ARRAY | VT_UI1;
varBLOB.parray = psa;
try
{
AfxOleInit(); //Open a connection
pConnection.CreateInstance(__uuidof(Connection));
hr = pConnection->Open(strCnn,"","",NULL); //Connect a DataBase
pRs.CreateInstance(__uuidof(Recordset));
pRs->Open("dxf_file",_variant_t((IDispatch *) pConnection,true),adOpenKeyset,adLockOptimistic,adCmdTable); //Open a Table pRs->AddNew();
pRs->PutCollect("filename",_variant_t("测试文件名称"));
pRs->Fields->GetItem("filedata")->AppendChunk(varBLOB);
pRs->Update();
pRs->Close();
pConnection->Close();
}
catch(_com_error &e)
{
// Notify the user of errors if any.
_bstr_t bstrSource(e.Source());
_bstr_t bstrDescription(e.Description());
CString sError;
sError.Format("Source : %s \n Description : %s\n",(LPCSTR)bstrSource,(LPCSTR)bstrDescription);
AfxMessageBox(sError);
}
_RecordsetPtr pRs = NULL;
_ConnectionPtr pConnection = NULL;
_variant_t varChunk;
HRESULT hr;
VARIANT varBLOB;
_bstr_t strCnn("Driver={SQL Server};Server=127.0.0.1;Database=subway;Uid=subway_admin;Pwd=admin;");
try
{
//Open a connection
AfxOleInit(); pConnection.CreateInstance(__uuidof(Connection));
hr = pConnection->Open(strCnn,"","",NULL);
pRs.CreateInstance(__uuidof(Recordset));
pRs->Open("dxf_file",_variant_t((IDispatch *) pConnection,true),adOpenKeyset,adLockOptimistic,adCmdTable);
//read data
long lDataLength = pRs->Fields->GetItem("filedata")->ActualSize;
varBLOB = pRs->GetFields()->GetItem("filedata")->GetChunk(lDataLength);
if(varBLOB.vt == (VT_ARRAY | VT_UI1))
{
BYTE *pBuf = NULL;
pBuf = (BYTE*)GlobalAlloc(GMEM_FIXED,lDataLength);
SafeArrayAccessData(varBLOB.parray,(void **)pBuf);
//Build a File in Windows Temp Directory
//char tmpPath[_MAX_PATH+1];
//GetTempPath(_MAX_PATH,tmpPath);
CString strFileName = "F:\\ASPHALT_1.bmp";
//strFileName = tmpPath+strFileName;
CFile outFile(strFileName,CFile::modeCreate|CFile::modeWrite);
LPSTR buffer = (LPSTR)GlobalLock((HGLOBAL)pBuf);
//outFile.WriteHuge(buffer,lDataLength);
outFile.Write(buffer,lDataLength);
GlobalUnlock((HGLOBAL)pBuf);
outFile.Close();
SafeArrayUnaccessData (varBLOB.parray);
}
pRs->Close();
pConnection->Close();
}
catch(_com_error &e)
{
// Notify the user of errors if any.
_bstr_t bstrSource(e.Source());
_bstr_t bstrDescription(e.Description());
CString sError;
sError.Format("Source : %s \n Description : %s\n",(LPCSTR)bstrSource,(LPCSTR)bstrDescription);
AfxMessageBox(sError);
}