delphi的萬能數據庫操作

好多人都抱怨delphi沒有提供一個可以把任意數據放入數據庫的控件，雖然說用代碼實現也不難，但是有控件會更方便，這次我終於還是抽出空來做了這么個控件，以后就可以直接拖放了。它支持把任意數據類型寫入數據庫，也可以從數據庫讀出到流，或是直接保存為文件。另外，我加了一些對常用圖像的處理，保存 jpg或是gif格式的圖像很方便，並且可以直接顯示到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; 
{保存到數據庫} 
function SaveToDatabase(AFileName: string): boolean; 
{追加到數據庫} 
function AppendToDatabase(AFileName: string): boolean; 
{從數據庫讀出到流} 
function LoadToStream(var AStream: TStream): boolean; 
{從數據庫讀出到文件} 
function LoadToFile(AFileName: string): boolean; 
{讀取圖片} 
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. 
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作者：清風古韻
來源：CSDN
原文：https://blog.csdn.net/ttpage/article/details/9161695
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