[转]Delphi存取JPEG、BMP图像到数据库完整解决方案

Delphi存取JPEG、BMP图像到数据库完整解决方案
本文来自Delphi之窗，原文地址：http://www.52delphi.com

unit Unit1;interfaceusesWindows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, DB, ExtDlgs, StdCtrls, ADODB, Grids, DBGrids, ExtCtrls,jpeg,DBCtrls;typeTForm1 = class(TForm)DBGrid1: TDBGrid;ADOConnection1: TADOConnection;ADOTable1: TADOTable;selectimage: TButton;savetodb: TButton;OpenPictureDialog1: TOpenPictureDialog;DataSource1: TDataSource;DBNavigator1: TDBNavigator;savetofile: TButton;Label1: TLabel;Label2: TLabel;Button1: TButton;Bevel1: TBevel;Bevel2: TBevel;GroupBox1: TGroupBox;Image1: TImage;Label3: TLabel;Label4: TLabel;DBImage1: TDBImage;procedure selectimageClick(Sender: TObject);procedure savetodbClick(Sender: TObject);procedure ADOTable1AfterScroll(DataSet: TDataSet);procedure savetofileClick(Sender: TObject);procedure Button1Click(Sender: TObject);procedure FormCreate(Sender: TObject);procedure ADOTable1BeforeScroll(DataSet: TDataSet);private{ Private declarations }public{ Public declarations }end;varForm1: TForm1;implementationuses unit2;{$R *.dfm}procedure TForm1.selectimageClick(Sender: TObject); //选择图像beginif openpicturedialog1.Execute thenimage1.Picture.LoadFromFile(openpicturedialog1.FileName );end;////如下保存方法only to sql and access'dataprocedure TForm1.savetodbClick(Sender: TObject); //保存图像varstrm:tmemorystream;ext:string;beginif image1.picture.Graphic <> nil then //避免image1中无图像保存出错beginext:=extractfileext(openpicturedialog1.FileName );strm := tmemorystream.Create ;tryimage1.Picture.Graphic.SaveToStream(strm);adotable1.Edit ;strm.Position :=0;DBImage1.dataField :=''; //dbimage只能显示BMP，否则myimage由BMP变为jpeg时会出错tblobfield(adotable1.FieldByName('myimage')).LoadFromStream(strm);//如需直接由文件保存 TBlobField(adotable1.FieldByName('myimage')).LoadFromFile(OpenPictureDialog1.FileName);//以下记录保存到数据库的图像格式if uppercase(ext) = '.BMP' thenbeginadotable1.FieldByName('isbmp').Value := 1;dbimage1.dataField := 'myimage';endelse if (uppercase(ext) = '.JPG') OR ( uppercase(ext) = '.JPEG') THENadotable1.FieldByName('isbmp').Value := 0;adotable1.Post ;finallystrm.Free ; //如果你选用TBLOBSTREAM类,程序运行到此语句会出错，可该语句前添入adotable1.editend;end;end;///如下显示方法不适用于paradox中的graphic字段的显示。procedure TForm1.adoTable1AfterScroll(DataSet: TDataSet); //显示图像varstrm:tadoblobstream;jpegimage:tjpegimage;bitmap:tbitmap;beginstrm := tadoblobstream.Create(tblobfield(adotable1.fieldbyname('MYIMAGE')),bmread);try //try1strm.position :=0;image1.Picture.Graphic := nil;DBIMAGE1.DataField := '';//显示时，BMP、JPEG两种图像数据必需分别处理if adotable1.fieldbyname('isbmp').asstring ='1' thenbegin //begin11bitmap := tbitmap.Create ;try //try11bitmap.LoadFromStream(strm);image1.Picture.Graphic := bitmap;DBIMAGE1.DataField := 'myimage';finallybitmap.Free;end; //end try11end //end begin11else if adotable1.fieldbyname('isbmp').asstring ='0' thenbegin //begin12jpegimage := tjpegimage.Create ;try //try12jpegimage.LoadFromStream(strm);image1.Picture.Graphic := jpegimage;finallyjpegimage.Free ;end; //end try12end; //end begin12finallystrm.Free ;end; //end try1end;////显示时必须分bmp and jpeg 两种情况处理，而保存可统一。procedure TForm1.savetofileClick(Sender: TObject);vartmpstr:string;beginif image1.Picture.Graphic <> nil thenbegintmpstr := openpicturedialog1.Filter;if adotable1.fieldbyname('isbmp').asstring ='1' thenbeginopenpicturedialog1.Filter := 'Bitmaps (*.bmp)|*.bmp';if openpicturedialog1.Execute thenimage1.Picture.SaveToFile(openpicturedialog1.FileName+'.bmp');endelsebeginopenpicturedialog1.Filter := 'JPEG Image File (*.jpg)|*.jpg';if openpicturedialog1.Execute thenimage1.Picture.SaveToFile(openpicturedialog1.FileName+'.jpg');end;openpicturedialog1.Filter := tmpstr;end;end;procedure TForm1.Button1Click(Sender: TObject);beginform2.Show;end;procedure TForm1.FormCreate(Sender: TObject);beginadoconnection1.Connected := true;adoconnection1.LoginPrompt := false;adotable1.Active := true;end;procedure TForm1.ADOTable1BeforeScroll(DataSet: TDataSet);begindbimage1.dataField :=''; //这条语句不能遗漏，不信你试试end;end.