delphi 保存图片到数据库

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