线程和主界面的交互的演示代码

求一个线程和主界面的交互的演示代码
求一个线程和主界面的交互的演示代码。线程和主界面处于两个Unit。线程中的user中不能引用主窗口。我只是想学习一下，线程和主界面交互的方法。去网上查了好几天资料，能查到的都是user中引用主窗口的方法。据说可以通过别的方法实现，求大神指点下了。跪求~~~

------解决方案--------------------
就用DELPHI自带的DEMO。DELPHI 7 中目录如下：
C:\Program Files\Borland\Delphi7\Demos\Threads\thrddemo.dpr
------解决方案--------------------
让我来教你一招吧：
用类似回调函数的方法：
第一：在线程的unit中定义：TCallFunction = procedure of object;
第二：在线程类中定义一个公共变量：FCallMain: TCallFunction;
第三：在主界面unit中定义一个函数：procedure TMain.Test(); 
第四：假设线程类的实例是ThreadA，让ThreadA.FCallMain=Test;
第五：在线程类就可以直接用 FCallMain了，
FCallMain的功能跟主界面的Test功能是一样的，如果Test函数有操作界面的操作，需要按照下面调用：
synchronize(FCallMain)；
明白了吧？？
------解决方案--------------------
synchronize实际上是把子线程的代码放到主线程里执行
另外线程和主线程交互的方法还可以用消息来实现
------解决方案--------------------
我給你個簡單的：
主單元：
unit TestThreadMainForm;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, Grids, DBGrids, DB, ADODB,TQueryThreadUnit, ComCtrls;

type
TForm1 = class(TForm)
ADODataSet1: TADODataSet;
DataSource1: TDataSource;
DBGrid1: TDBGrid;
Button1: TButton;
StatusBar1: TStatusBar;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin

//CoInitialize(nil);
try
TQueryThread.Create(ADODataset1,DataSource1,StatusBar1);
StatusBar1.SimpleText := '請等待，正在打開數據表......';
StatusBar1.SimplePanel := True;
finally
//CoUninitialize;
end;
//ADODataSet1.Open;
end;

end.
線程單元：
unit TQueryThreadUnit;

interface

uses
Classes,ADODB,DB,ActiveX,ComCtrls;

type
TQueryThread = class(TThread)
private
FDataSet :TADODataSet;
FDataSource :TDataSource;
FStatusBar :TStatusBar;
procedure HookUpUI;
{ Private declarations }
protected
procedure Execute; override;
public
constructor Create(ADataSet:TADODataSet;ADataSource:TDataSource;AStatusBar:TStatusBar);virtual;
end;

implementation

{ Important: Methods and properties of objects in visual components can only be
used in a method called using Synchronize, for example,

Synchronize(UpdateCaption);

and UpdateCaption could look like,

procedure TQueryThread.UpdateCaption;
begin
Form1.Caption := 'Updated in a thread';
end; }

{ TQueryThread }
constructor TQueryThread.Create(ADataSet:TADODataSet;ADataSource:TDataSource;AStatusBar:TStatusBar);
begin
inherited Create(True);
FDataSet := ADataSet;
FDataSource := ADataSource;
FStatusBar := AStatusBar;
FreeOnTerminate := True;
Resume;
end;

procedure TQueryThread.Execute;
begin
{ Place thread code here }
CoInitialize(nil);
try
if not FDataSet.Active then FDataSet.Open;
Synchronize(HookUpUI);
finally
CoUninitialize;
end;
end;

procedure TQueryThread.HookUpUI;
begin
FDataSource.DataSet := FDataSet;
FStatusBar.SimpleText := '已經打開數據表！';
end;
end.