VC保存和显示数据库图像(JPG、JPEG)

源码下载：http://download.csdn.net/source/2840272

程序运行界面显示如下：

简述关键代码如下：

 

1、保存图片数据到数据库

以下是代码片段： //JPG图片保存到数据库     try     {         _RecordsetPtr    pRecordset;         pRecordset.CreateInstance(__uuidof(Recordset));         pRecordset->Open("SELECT * FROM jpg",_variant_t((IDispatch*)pConnection),adOpenStatic,adLockOptimistic,adCmdText);         pRecordset->AddNew();         pRecordset->Fields->Item["jpgid"]->Value = (_variant_t)m_JPGId;//jpgid         VARIANT pvList;         SetPictureToVariant(pvList,(unsigned char *)m_pJPGBuffer);         pRecordset->Fields->Item["jpgimage"]->AppendChunk(pvList); //JPG图像文件         VariantClear(&pvList);                  pRecordset->Update();         pRecordset->Close();         AfxMessageBox("JPG图像保存成功！");         m_JPGId == "";         UpdateData(false);     }     catch(...)     {         AfxMessageBox("数据库读取失败");         return;     }

 

其中SetPictureToVariant如下：

以下是代码片段： void CBMPinDBDlg::SetPictureToVariant(VARIANT &pvList, unsigned char *sPicture)     {         SAFEARRAYBOUND saBound[1];         saBound[0].cElements = m_nFileLen;         saBound[0].lLbound = 0;         SAFEARRAY *pSA = SafeArrayCreate(VT_UI1, 1, saBound);             for (long l = 0; l < (long)m_nFileLen; l ++)         {             SafeArrayPutElement( pSA, &l, (void*)&sPicture[l]);                 }         VariantClear(&pvList);         pvList.vt = VT_UI1 | VT_ARRAY;         pvList.parray = pSA;     }

 

2、从数据库读取图像文件并且显示在界面

   

以下是代码片段：  //从数据库里取JPG图像文件     try     {         _RecordsetPtr    pRecordset;         char sSql[129];         sprintf(sSql,"SELECT *FROM jpg WHERE jpgid=’%s’",m_JPGId);         pRecordset.CreateInstance(__uuidof(Recordset));         pRecordset->Open(sSql,_variant_t((IDispatch*)pConnection),adOpenStatic,adLockOptimistic,adCmdText);         if (pRecordset->adoEOF)         {             CString str;             str.Format("没有JPGid为: %s 的JPG图像!",m_JPGId );             AfxMessageBox(str);             Invalidate();             m_JPGId = "";             UpdateData(false);             m_EidtJPGId.SetFocus();             return;         }         _variant_t pvList ;                 long lDataSize = pRecordset->GetFields()->GetItem("jpgimage")->ActualSize;         m_nFileLen = (DWORD)lDataSize;         if(lDataSize > 0)         {             _variant_t            varBLOB;             varBLOB = pRecordset->GetFields()->GetItem("jpgimage")->GetChunk(lDataSize);             //把二进制格式的图片转为图片格式             try             {                 if(varBLOB.vt == (VT_ARRAY | VT_UI1))                 {                     if(m_pJPGBuffer = new char[lDataSize+1])                             {                             char *pBuf = NULL;                         SafeArrayAccessData(varBLOB.parray,(void **)&pBuf);                         memcpy(m_pJPGBuffer,pBuf,lDataSize);                                         SafeArrayUnaccessData (varBLOB.parray);                         m_nFileLen = lDataSize;                                                  //m_pJPGBuffer -> pPicture                                             HGLOBAL hMem = ::GlobalAlloc( GMEM_MOVEABLE, m_nFileLen );                         LPVOID lpBuf = ::GlobalLock( hMem );                                             memcpy(lpBuf,m_pJPGBuffer,m_nFileLen);                                                  ::GlobalUnlock( hMem );                                                  if ( CreateStreamOnHGlobal( hMem, TRUE, &pStream ) !=S_OK )                                  return ;                                                  if ( OleLoadPicture( pStream, m_nFileLen, TRUE, IID_IPicture, ( LPVOID * )&pPicture ) !=S_OK )                             return ;                                                  Invalidate();//在界面显示                                      }                 }             }             catch(...)             {                 AfxMessageBox("从数据库中读取jpg图像有错！");                 return;             }                      }              }     catch(...)     {         AfxMessageBox("数据库读取失败");         return;     }

具体的程序请参考附带的例子，例子里面有详细的注释。