保存图片到数据库,从数据库里提取图片 - beeone

1、如何实现在Microsoft Access数据库中的图像存储： 
这里是利用TStream的子类TMemoryStream向Microsoft Access数据库中存储图像的。 
下面的这段代码是在按了“保存”按钮之后所触发的事件处理程序： 
procedure TForm1.Button1Click(Sender: TObject); 
Var 
MyJPEG : TJPEGImage; 
MS: TMemoryStream; 
Begin 
MyJPEG := TJPEGImage.Create; 
Try 
With MyJPEG do 
Begin 
Assign(Image.Picture.Graphic); 
MS:=TMemoryStream.create; 
SaveToStream(MS); 
MS.Position := 0; 
Table1.Edit; 
TBlobField(Table1.FieldbyName(\'Image\')).LoadFromStream(MS); 
Table1.Post; 
Messagebox(Getactivewindow(), \'图像保存完毕！\', \'保存\', MB_OK); 
End; 
Finally 
MyJPEG.Free; 
End; 
End; 
在这段代码里TStream的子类TMemoryStream利用内存流起到了将BMP格式转化为JPEG格式 
的中间桥梁的作用。 

2、如何将图像从Microsoft Access数据库中取出并显示出来： 
下面的这段代码是在按了“查看图像”按钮之后所触发的事件处理程序： 
procedure TForm1.Button1Click(Sender: TObject); 
Var 
MyJPEG : TJPEGImage; 
MS : TMemoryStream; 
Begin 
Try 
MS := TMemoryStream.Create; 
TBlobField(Query1.FieldByName(\'Image\')).SaveToStream(MS); 
MS.Position := 0; 
MyJPEG := TJPEGImage.Create; 
MyJPEG.LoadFromStream(MS); 
DBImage1.Picture.Bitmap.Assign(MyJPEG); 
//或是Sender.Picture.Assign(MyJPEG); 
Finally 
MS.Free; 
MyJPEG.Free; 
End; 
End; 

==========================================================================

图片保存到数据库的例子：   
    
  //保存     
  procedure   TForm1.ImageIntoDBBitBtnClick(Sender:   TObject);     
  begin     
      try     
          with   Query1   do     
              begin     
                  close;     
                  sql.clear;     
                  sql.add(\'insert   into   img   (imga)   values(:imag)\');     
              end;     
          try     
              if   FileName<>\'\'   then     
                  ParamByName(\'Img\').LoadfromFile(FileName,ftGraphic)     
              else     
                  ParamByName(\'Img\')   .asBlob:=\'\';     
              Query1.ExecSQL;     
          except     
              ShowMessage(\'图片保存出错！\');     
              exit;     
          end;     
      except     
      end;     
  end;     
      
  //读取     
  procedure   TForm1.ImageFromDBBitBtnClick(Sender:   TObject);     
  var     
      m_jpegstream:tmemorystream;     
  begin     
      with   Query1   do     
      begin     
          close;     
          sql.clear;     
          sql.Add(\'select   imga   from   img\');     
          try     
              Open;     
          except     
              exit;     
          end;     
      end;     
      if   (Query1.FieldByName(\'imga\')   as   tblobfield).asstring=\'\'   then     
      begin     
          exit;     
      end     
      else     
      begin     
          try     
          try     
              m_jpegStream:=TMemoryStream.Create;     
              (Query1.fieldbyname(\'imga\')   as   TBlobField).SaveToStream(m_JpegStream);     
              m_JpegStream.Position:=0;     
              try     
                  image2.Picture.Graphic:=nil;     
                  image2.Picture.Graphic:=TJpegImage.Create;     
                  image2.Picture.Graphic.LoadFromStream(m_JpegStream);     //读Jpeg     
              except     
                  Image2.Picture.Bitmap.LoadFromStream(m_JpegStream);       //读Bmp     
              end;     
          except     
          end;     
          finally     
              m_JpegStream.Free;     
              Query1.Close;     
              Query1.UnPrepare;     
          end;     
      end;     
  end;     
      
  //BMP转换为JPG     
  procedure   TStuXXSLForm.LoadImageBitBtnClick(Sender:   TObject);     
  var     
      MyJpeg:TJpegImage;     
  begin     
      inherited;     
      if   OpenPictureDialog1.Execute   then     
      begin     
          FileName:=OpenPictureDialog1.FileName;     
          Image1.Picture.LoadFromFile(FileName);     
          if   ExtractFileExt(FileName)=\'.Bmp\'   then     
          begin     
              MyJpeg:=   TJpegImage.Create;     
              MyJpeg.Assign(Image1.Picture.Bitmap);     
              FileName:=\'Photo.Jpg\';     
              MyJpeg.SaveToFile(FileName);     
              MyJpeg.Free;     
          end;     
      end;     
  end;

用到TBlobField的时候要在接口包含DB，用到TJPEGImage时要在接口包含Jpeg