在线等,散分啦!SQL数据库能不能存JPG格式图片?如何做啊??
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var
pjpg:tjpegimage;
pic:TMemoryStream;
begin
pjpg:=tjpegimage.Create;
pjpg.LoadFromFile(F:\JPG.jpg);
pic:=TMemoryStream.Create;
pjpg.SaveToStream(pic);
pic.Position:=0;
TBlobField(dataset.FieldByName('Img')).LoadFromStream(pic);
dataset.post;
pic.Free;
pjpg.free;
end;
从数据库取出
var
pjpg:tjpegimage;
pic:TMemoryStream;
begin
pjpg:=tjpegimage.Create;
pic:=TMemoryStream.Create;
TBlobField(dataset.FieldByName('Img')).savetoStream(pic);
pic.positon:=0;
pjpeg.LoadFromStream(pic);
image.graphi.bmp.assign(pjpeg);
end;end;
TBlobField(FieldByName('text')).LoadFromFile(‘c;\a.jpg’);
这样,显示时就不需要分类处理显示,但导出文件时需要再根据要求转换
提示“invalid bitmap file format”
//将图片格式均转换为jpg进行存入。
pjpg:=TJpegImage.Create;
if extractfileext(openpicture1.dialog.filename)='.bmp' then
pjpg.assign(Carimage.picture.bitmap)
else
if (extractfileext(openpicture1.dialog.filename)='.jpg') or (extractfileext(openpicture1.dialog.filename)='.jpeg') then
pjpg.assign(carimage.picture)
else
exit;
try
pic:=TMemoryStream.Create;
pjpg.SaveToStream(pic);
pic.Position:=0;
TBlobField(DM.CarQuery.fieldbyname ('照片')).LoadFromStream(pic); finally
pic.Free;
pjpg.free;bmp1.free;
end;//读取时try
pjpg:=tjpegimage.Create;
pic:=TMemoryStream.Create;
TBlobField(DM.CarQuery.fieldbyname ('照片')).savetoStream(pic);
if pic.Size=0 then
exit;
pic.position:=0;
pjpg.LoadFromStream(pic);
Carimage.picture.assign(pjpg);
finally
pjpg.Free ;
pic.Free ;
end;
ms: TStringStream;
File_Type: string;
begin
if not (Shy_qry.eof and Shy_qry.bof) then
begin
ms := TStringStream.Create('');
OpenPictureDialog1.InitialDir := sm_directory;
if (OpenPictureDialog1.Execute) and (trim(OpenPictureDialog1.filename) <> '') then
begin
File_Type := ExtractFileExt(OpenPictureDialog1.filename);
if UpperCase(File_Type) <> '.JPG' then
begin
OpenPictureDialog1.Filename := BmpToJpg(OpenPictureDialog1.filename);
end;
Image1.picture.loadfromfile(OpenPictureDialog1.filename);
Image1.Picture.Graphic.SaveToStream(ms);
if not (Shy_qry.State in [dsedit, dsinsert]) then
begin
Shy_qry.Edit;
end;
Shy_qry.Fieldbyname('photo_type').AsString := Copy(OpenPictureDialog1.filename, length(OpenPictureDialog1.filename) - 2, 3);
Ms.Position := 0;
(Shy_Qry.Fieldbyname('photo') as Tblobfield).LoadFromStream(ms);
if Shy_Qry.State in [dsedit] then
begin
Shy_qry.Post;
end;
end;
ms.Free;
end
else
begin
Application.MessageBox('请先输入数据再提取照片!', '错误', MB_ICONSTOP + MB_OK);
end;
end;
高红岩(ghyghost)
近日笔者书写一个小型的学生管理系统时,需要用到ADO控件存取SQL Server数据库图片,查看资料发现基本都是针对BMP文件进行操作(巨增数据库大小),但发现了★eagletian★高手翻译的ADO英文技术文档,里面涉及到了数据库存取JPEG文件的关键技术,在win98+sql server桌面版中测试通过,运行良好,现于源码公开如下:
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
ExtCtrls, DBCtrls, Grids, DBGrids, Db, ADODB,jpeg, StdCtrls,dbtables;
{一定要USES JPEG单元,使能存储JPG文件格式}
type
TForm1 = class(TForm)
DataSource1: TDataSource;
ADOQuery1: TADOQuery;
DBGrid1: TDBGrid;
DBNavigator1: TDBNavigator;
Image1: TImage;
savebutton: TButton;
showbutton: TButton;
OpenDialog1: TOpenDialog;
ADOQuery1id: TIntegerField;
ADOQuery1pic: TBlobField;
procedure savebuttonClick(Sender: TObject);
procedure showbuttonClick(Sender: TObject);
procedure DBNavigator1Click(Sender: TObject; Button: TNavigateBtn);
private
{ Private declarations }
public
{ Public declarations }
end;var
Form1: TForm1;implementation{$R *.DFM}function JpegStartsInBlob(PicField:TBlobField):integer;
var
ghy: TADOBlobstream;
buffer:Word;
hx: string;
begin
Result := -1;
ghy := TADOBlobstream.Create(PicField, bmRead);
try
while (Result = -1) and (ghy.Position + 1 < ghy.Size) do
begin
ghy.ReadBuffer(buffer, 1);
hx:=IntToHex(buffer, 2);
if hx = 'FF' then begin
ghy.ReadBuffer(buffer, 1);
hx:=IntToHex(buffer, 2);
if hx = 'D8' then Result := ghy.Position - 2
else if hx = 'FF' then
ghy.Position := ghy.Position-1;
end; //if
end; //while
finally
ghy.Free
end; //try
end;
procedure TForm1.savebuttonClick(Sender: TObject);
var
picstream:tadoblobstream;
begin
adoquery1.edit;
picstream:=tadoblobstream.Create(tblobfield(adoquery1.fields[1]),bmWrite);
if form1.opendialog1.execute then
begin
picstream.LoadFromFile(opendialog1.filename);
picstream.Position:=0;
adoquery1.edit;
tblobfield(adoquery1.Fields[1]).loadfromstream(picstream);
adoquery1.post;
end;
end;procedure TForm1.showbuttonClick(Sender: TObject);
var
ghy:TADOBlobstream;
pic:tjpegimage;
begin
ghy := TADOBlobstream.Create(Adoquery1pic, bmRead);
try
ghy.Seek(JpegStartsInBlob(Adoquery1pic),soFromBeginning);
Pic:=TJpegImage.Create;
try
Pic.LoadFromStream(ghy);
Image1.Picture.Graphic:=Pic;
finally
Pic.Free;
end;
finally
ghy.Free
end;
end;procedure TForm1.DBNavigator1Click(Sender: TObject; Button: TNavigateBtn);
begin
if button in [nbFirst, nbPrior, nbNext, nbLast] then showbutton.Click;
end;end.如果数据库中要存储的是BMP文件,则在procedure TForm1.showbuttonClick(Sender: TObject);过程中代码更改如下即可存储显示BMP文件格式的操作。
procedure TForm1.showbuttonClick(Sender: TObject);
var
ghy:TADOBlobstream;
pic:tbitmap;
begin
ghy := TADOBlobstream.Create(Adoquery1pic, bmRead);
try
{ ghy.Seek(JpegStartsInBlob(Adoquery1pic),soFromBeginning);}
Pic:=Tbitmap.Create;
try
Pic.LoadFromStream(ghy);
Image1.Picture.Graphic:=Pic;
finally
Pic.Free;
end;
finally
ghy.Free
end;
end;
到此用DELPHI存取JPEG文件到SQL Server数据库中的具体操作已经叙述完毕。