delphi的万能数据库操作

好多人都抱怨delphi没有提供一个可以把任意数据放入数据库的控件，虽然说用代码实现也不难，但是有控件会更方便，这次我终于还是抽出空来做了 这么个控件，以后就可以直接拖放了。它支持把任意数据类型写入数据库，也可以从数据库读出到流，或是直接保存为文件。另外，我加了一些对常用图像的处理， 保存jpg或是gif格式的图像很方便，并且可以直接显示到image上。

unit RaDBOLE;

interface

uses

SysUtils, Classes, DB, DBTables, JPEG, ExtCtrls, GIFCtrl;

type

TImageType = (itBMP, itJPG, itGIF, itOther);

TOnSaveData = procedure(Sender: TObject) of object;

TOnLoadData = procedure(Sender: TObject) of object;

TOnShowImage = procedure(Sender: TObject; ImageType: TImageType) of object;

type

TRaDBOLE = class(TComponent)

private

fDataSet: TDataSource;

fDataField: string;

fImage: TImage;

fGifImage: TRxGIFAnimator;

fOnSaveData: TOnSaveData;

fOnLoadData: TOnLoadData;

fOnShowImage: TOnShowImage;

protected

public

constructor Create(AOwner: TComponent); override;

{保存到数据库}

function SaveToDatabase(AFileName: string): boolean;

{追加到数据库}

function AppendToDatabase(AFileName: string): boolean;

{从数据库读出到流}

function LoadToStream(var AStream: TStream): boolean;

{从数据库读出到文件}

function LoadToFile(AFileName: string): boolean;

{读取图片}

procedure GetImage;

published

property DataSet: TDataSource read fDataSet write fDataSet;

property DataField: string read fDataField write fDataField;

property Image: TImage read fImage write fImage;

property GifImage: TRxGIFAnimator read fGifImage write fGifImage;

property OnSaveData: TOnSaveData read fOnSaveData write fOnSaveData;

property OnLoadData: TOnLoadData read fOnLoadData write fOnLoadData;

property OnShowImage: TOnShowImage read fOnShowImage write fOnShowImage;

end;

procedure Register;

implementation

procedure Register;

begin

RegisterComponents('Rarnu Components', [TRaDBOLE]);

end;

{ TRaDBOLE }

function TRaDBOLE.AppendToDatabase(AFileName: string): boolean;

var

mm: tmemorystream;

begin

result := True;

mm := tmemorystream.Create;

mm.LoadFromFile(AFileName);

mm.Position := 0;

try

fDataSet.DataSet.Append;

tblobfield(fDataSet.DataSet.FieldByName(fDataField)).LoadFromStream(mm);

fDataSet.DataSet.Post;

except

result := False;

end;

mm.Free;

if Assigned(OnSaveData) then

OnSaveData(Self);

end;

constructor TRaDBOLE.Create(AOwner: TComponent);

begin

inherited Create(AOwner);

fDataSet := nil;

fDataField := '';

fImage := nil;

end;

procedure TRaDBOLE.GetImage;

var

ww: tmemorystream;

JPEG: TJPEGImage;

IT: TImageType;

begin

if fImage = nil then Exit;

ww := tmemorystream.Create;

tblobfield(fDataSet.DataSet.FieldByName(fDataField)).SaveToStream(ww);

try

fImage.Picture.Assign(fDataSet.DataSet.FieldByName(fDataField));

IT := itBMP;

except

try

JPEG := TJPEGImage.Create;

JPEG.Assign(fDataSet.DataSet.FieldByName(fDataField));

fImage.Picture.Assign(JPEG);

IT := itJPG;

except

try

if fGifImage = nil then Exit;

fGifImage.Image.Assign(fDataSet.DataSet.FieldByName(fDataField));

IT := itGIF;

except

IT := itOther;

end;

end;

end;

//fImage.Picture.Graphic.LoadFromStream(ww);

ww.Free;

if Assigned(OnShowImage) then

OnShowImage(Self, IT);

end;

function TRaDBOLE.LoadToFile(AFileName: string): boolean;

var

tt: tmemorystream;

begin

result := True;

tt := tmemorystream.Create;

try

tblobfield(fDataSet.DataSet.FieldByName(fDataField)).SaveToStream(tt);

tt.Position := 0;

tt.SaveToFile(AFileName);

except

result := False;

end;

tt.Free;

if Assigned(OnLoadData) then

OnLoadData(Self);

end;

function TRaDBOLE.LoadToStream(var AStream: TStream): boolean;

var

tt: tmemorystream;

begin

result := True;

tt := tmemorystream.Create;

try

tblobfield(fDataSet.DataSet.FieldByName(fDataField)).SaveToStream(tt);

tt.Position := 0;

AStream := tt;

except

result := False;

end;

tt.Free;

if Assigned(OnLoadData) then

OnLoadData(Self);

end;

function TRaDBOLE.SaveToDatabase(AFileName: string): boolean;

var

mm: tmemorystream;

begin

result := True;

mm := tmemorystream.Create;

mm.LoadFromFile(AFileName);

mm.Position := 0;

try

fDataSet.Edit;

tblobfield(fDataSet.DataSet.FieldByName(fDataField)).LoadFromStream(mm);

fDataSet.DataSet.Post;

except

result := False;

end;

mm.Free;

if Assigned(OnSaveData) then

OnSaveData(Self);

end;

end.