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. 
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作者：清风古韵
来源：CSDN
原文：https://blog.csdn.net/ttpage/article/details/9161695
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