¿Como trabajar Multithreads en Delphi?

Unit uMain ;

interface

{$I CompVer.

Inc}

uses

{$IFDEF D6H}

Variants,

{$ENDIF}

Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms,

Dialogs, StdCtrls, DB, ABSMain, Grids, DBGrids ;

type

TMainForm = class(TForm)

DBGrid1 : TDBGrid ;

dsChat : TDataSource ;

dbDemos : TABSDatabase ;

tblChat : TABSTable ;

GroupBox2 : TGroupBox ;

Label1 : TLabel ;

Label2 : TLabel ;

Button1 : TButton ;

Button2 : TButton ;

procedure FormCreate(Sender : TObject) ;

procedure FormDestroy(Sender : TObject) ;

procedure Button1Click(Sender : TObject) ;

procedure Button2Click(Sender : TObject) ;

private

{ Private declarations }

public

{ Public declarations }

end ;

TChatMemberThread = class(TThread)

private

FName : string ;

FSession : TABSSession ;

FDatabase : TABSDatabase ;

FTable : TABSTable ;

procedure RefreshTable ;

protected

procedure Execute ; override ;

public

constructor Create(Name : string) ;

destructor Destroy ; override ;

end ;

const ChatMessages : array[0.

9] of string = ('Hi', 'Hello', 'I''m here', 'Banzay!

',

'Cool', 'how are you?

', 'fine', 'who is here', 'I''m here', 'BzzzZzzz.

') ;

const ChatMembersNames : array[0.

9] of string = ('Roger', 'Janet', 'Dana', 'Bill',

'Kim', 'Bruce', 'Phil', 'Roberto', 'Michael', 'Claudia') ;

const DataBaseFileName : String = '.

\ . \ Data \ Demos.

Abs' ;

var

MainForm : TMainForm ;

implementation

{$IFDEF D6H}

uses StrUtils ;

{$ELSE}

function RandomFrom(const AValues : array of string) : string ;

begin

Result : = AValues[Random(High(AValues) + 1)] ;

end ;

{$ENDIF}

{$R * .

Dfm}

{ TChatMemberThread }

constructor TChatMemberThread.

Create(Name : string) ;

begin

inherited Create(True) ;

FName : = Name ;

FreeOnTerminate : = True ;

FSession : = TABSSession.

Create(nil) ;

FSession.

AutoSessionName : = True ;

FDatabase : = TABSDatabase.

Create(nil) ;

FDatabase.

DatabaseName : = 'db_' + Name + '_' + IntToStr(Random(1000)) ;

FDatabase.

DatabaseFileName : = ExtractFilePath(Application.

ExeName) + DataBaseFileName ;

FDatabase.

SessionName : = FSession.

SessionName ;

FDatabase.

MultiUser : = True ;

FDatabase.

Open ;

FTable : = TABSTable.

Create(nil) ;

FTable.

SessionName : = FSession.

SessionName ;

FTable.

DatabaseName : = FDatabase.

DatabaseName ;

FTable.

TableName : = 'Chat' ;

FTable.

Open ;

end ;

destructor TChatMemberThread.

Destroy ;

begin

FTable.

Free ;

FDatabase.

Free ;

FSession.

Free ;

inherited ;

end ;

procedure TChatMemberThread.

Execute ;

var

I : Integer ;

begin

for I : = 0 to 20 do

begin

if Terminated then Exit ;

if MainForm.

TblChat.

Active and MainForm.

TblChat.

Exists then

begin

FTable.

AppendRecord([FName, RandomFrom(ChatMessages)]) ;

{ refreshing must be done in a synchronzied method since it will modify

the contents of the grid and the grid can only be modified from the main

VCL thread }

Synchronize(RefreshTable) ;

Sleep(Random(100)) ;

end ;

end ;

end ;

procedure TMainForm.

FormCreate(Sender : TObject) ;

begin

Randomize ;

dbDemos.

DatabaseFileName : = ExtractFilePath(Application.

ExeName) + DataBaseFileName ;

tblChat.

CreateTable ;

tblChat.

Open ;

end ;

procedure TMainForm.

FormDestroy(Sender : TObject) ;

begin

tblChat.

DeleteTable ;

end ;

procedure TMainForm.

Button1Click(Sender : TObject) ;

var

I : Integer ;

begin

for I : = 0 to 9 do

with TChatMemberThread.

Create(ChatMembersNames[I]) do

begin

Priority : = tpLower ;

Resume ;

end ;

end ;

procedure TMainForm.

Button2Click(Sender : TObject) ;

begin

tblChat.

Close ;

tblChat.

EmptyTable ;

tblChat.

Open ;

end ;

procedure TChatMemberThread.

RefreshTable ;

begin

MainForm.

TblChat.

Refresh ;

end ;

end.