各位大虾指点一下如何操作数据库中的图片

Question

小弟初次涉及到数据库中的图片操作，用的是MS_SQL Server,在其中建立了Image类型的字段存储图片，界面上用的Express 的TdxDBGraphicEdit ，绑定数据后发现只能打开存储BMP格式的图片文件，其他的它们应该都支持的，那要如何操作呢？请执教！谢谢！

Answer 1

给你一段代码不过是c++的，应该和pascal差不多自己研究以下了
void __fastcall TForm2::BitBtn2Click(TObject *Sender)
{
   OpenPictureDialog1->FileName="";
     if (OpenPictureDialog1->Execute())
        {
           String f=OpenPictureDialog1->FileName;
           if (FileExists(f))
              {
                 String ext=ExtractFileExt(f).LowerCase();
                 if (ext==".bmp" || ext==".jpg"|| ext==".jpeg")
                     {
                        String jpg=ChangeFileExt(ExtractFileName(f),".jpg");
                        TJPEGImage *j=new TJPEGImage;
                        if (ext==".bmp")
                           {
                              Graphics::TBitmap *b=new Graphics::TBitmap;
                              b->LoadFromFile(f);
                              j->Assign(b);
                              j->CompressionQuality=90;
                              j->Compress();
                              delete b;
                           }
                        else
                           {
                              TFileStream *fs=new TFileStream(f,fmOpenRead);
                              j->LoadFromStream(fs);
                              delete fs;
                           }
                        DataModule3->USRIFTable->Edit();
                    //  DataModule1->ADODataSet1->Edit();
                    //  DBEdit2->Text=jpg;                        TField *zd = DataModule3->USRIFTable->FieldByName("PHOTO");
                    //  TField *zd=DataModule1->ADODataSet1->FieldByName("照片图像");
                        zd->Clear();  // 先清字段
                        TStream *bs=DataModule3->USRIFTable->CreateBlobStream(zd,bmWrite);
                        bs->Position=0;
                        j->SaveToStream(bs);
                        delete j;
                        delete bs;
                        DispJpg();
                     }
              }
        }

Answer 2

procedure Tfrm_customer.btn_imageClick(Sender: TObject);
var
strm:Tmemorystream;
begin
strm:=tmemorystream.Create;
if not openpicturedialog1.Execute then exit;
image1.Picture.Bitmap.LoadFromFile(openpicturedialog1.filename);
image1.Picture.Bitmap.SaveToStream(strm);//将图像数据写入内存流
adotable1.Edit;
(adotable1.FieldByName('cus_image') as TBlobField).loadfromstream(strm);//从内存流中装载图像数据
//adotable1.FieldValues['cus_imagef']:=extractfilename(openpicturedialog1.filename);
strm.Free;
end;在上段代码中,可以装载BMP图像数据,若要装载JPG图像数据,则相应代码为:
procedure Tfrm_customer.btn_imageClick(Sender: TObject);
var
strm:Tmemorystream;
begin
strm:=tmemorystream.Create;
if not openpicturedialog1.Execute then exit;
TJPEGImage(image1.Picture.Graphic).LoadFromFile(openpicturedialog1.filename); //类型强制转换
TJPEGImage(image1.Picture.Graphic).SaveToStream(strm);//将图像数据写入内存流
adotable1.Edit;
(adotable1.FieldByName('cus_image') as TBlobField).loadfromstream(strm);//从内存流中装载图像数据
strm.Free;
end;

Answer 3

用TFileStream吧，可以搞定任何文件。//ADOTable
var
  TmpFileStream : TFileStream;
begin 
  ...
  open;
  locate...
  edit;
  if FileExists(trim(edtFileName.Text)) then begin
  TmpFileStream := TFileStream.Create(trim(edtFileName.Text), fmOpenRead);
  try
    TBlobField(FieldByName('ImageField')).LoadFromStream(TmpFileStream);              
    Post;
  finally
    TmpFileStream.Free;
  end;
end;

Answer 4

procedure TForm1.Button1Click(Sender: TObject);
begin
   if OpenPictureDialog1.Execute then
   Image1.Picture.LoadFromFile(OpenPictureDialog1.FileName);
end;procedure TForm1.Button2Click(Sender: TObject);
begin
   ADOTable1.Append;
   TBlobField(ADOTable1.FieldByName('FImage')).LoadFromFile(OpenPictureDialog1.FileName);
   ADOTable1.Post;
end;