Delphi download multithreading - multithreading

Question

My initial question was misleading, I'll try to improve it:
I was able to write a small delphi programme, which is able to do a threaded download by using indy's idHTTP. It consists of 2 files:
the form:
interface
type
TForm1 = class(TForm)
Button1: TButton;
Label1: TLabel;
Button2: TButton;
IdSSLIOHandlerSocketOpenSSL1: TIdSSLIOHandlerSocketOpenSSL;
IdAntiFreeze1: TIdAntiFreeze;
IdHTTP: TIdHTTP;
ProgressBar1: TProgressBar;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
private
{ Private-Deklarationen }
public
{ Public-Deklarationen }
procedure UpdateLabel(BytesDone: Integer);
procedure UpdateProgressBar(AWorkCount: Int64);
procedure InitProgressBar(AWorkCountMax: Int64);
procedure ResetProgressBar;
end;
var
Form1: TForm1;
uStopDownloading: Boolean;
implementation
{$R *.dfm}
uses Unit2;
procedure TForm1.Button1Click(Sender: TObject);
var
HTTPThread: TIdHTTPThread;
begin
HTTPThread := TIdHTTPThread.Create(True);
HTTPThread.Url := 'https://www.bot-factory.de/tmp/lorem7.txt';
HTTPThread.EncodedStr := '';
HTTPThread.Filename := 'C:\test.txt';
HTTPThread.FreeOnTerminate := True;
HTTPThread.Resume;
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
idhttp.Disconnect;
end;
procedure TForm1.UpdateLabel(BytesDone: Integer);
begin
Label1.caption := format('%.0n',[extended(BytesDone+0.0)]) +' bytes loaded.';
end;
procedure TForm1.UpdateProgressBar(AWorkCount: Int64);
begin
ProgressBar1.Position := AWorkCount;
end;
procedure TForm1.InitProgressBar(AWorkCountMax: Int64);
begin
Screen.Cursor := crHourGlass;
ProgressBar1.Max := AWorkCountMax;
ProgressBar1.Position := 0;
end;
procedure TForm1.ResetProgressBar;
begin
Screen.Cursor := crDefault;
showmessage('Job is done');
end;
END.
And the Thread-Unit:
interface
uses
Classes, IdBaseComponent, IdComponent, IdTCPConnection, IdTCPClient, IdHTTP, sysutils;
type
TIdHTTPThread = class(TThread)
private
FURL: AnsiString;
FencodedStr: string;
FFilename: AnsiString;
FBytesDone,FProgress,FWorkCountMax: Int64;
IdHTTP: TIdHTTP;
procedure OnWork(ASender: TObject; AWorkMode: TWorkMode; AWorkCount: Int64);
procedure OnWorkBegin(ASender: TObject; AWorkMode: TWorkMode; AWorkCountMax: Int64);
procedure OnWorkEnd(ASender: TObject; AWorkMode: TWorkMode);
procedure Updatelabel;
procedure UpdateProgressBar;
procedure InitProgressBar;
procedure ResetProgressBar;
procedure Disconnect;
public
Constructor Create(CreateSuspended: Boolean);
Destructor Destroy; override;
property Url: AnsiString read FURL write FUrl;
property encodedstr: String read FencodedStr write FencodedStr;
property Filename: AnsiString read FFilename write FFilename;
protected
procedure Execute; override;
end;
implementation
uses
Unit1; // Formular Unit
constructor TIdHTTPThread.Create(CreateSuspended: Boolean);
begin
inherited Create(Suspended);
IdHTTP := TIdHTTP.Create;
IdHTTP.OnWork := OnWork;
IdHTTP.OnWorkBegin := OnWorkBegin;
IdHTTP.OnWorkEnd := OnWorkEnd;
//IdHTTP.Disconnect := Disconnect;
end;
destructor TIdHTTPThread.Destroy;
begin
IdHTTP.Free;
inherited;
end;
procedure TIdHTTPThread.Execute;
var
DestStream: TFileStream;
begin
DestStream := TFileStream.Create(Filename, fmCreate);
try
IdHTTP.Get(Url, DestStream);
finally
DestStream.Free;
end;
end;
procedure TIdHTTPThread.OnWork(ASender: TObject; AWorkMode: TWorkMode; AWorkCount: Int64);
begin
FBytesDone := AWorkCount;
FProgress := AWorkCount;
Synchronize(Updatelabel);
Synchronize(UpdateProgressBar);
end;
procedure TIdHTTPThread.OnWorkBegin(ASender: TObject; AWorkMode: TWorkMode; AWorkCountMax: Int64);
begin
FWorkCountMax := AWorkCountMax;
Synchronize(InitProgressBar);
end;
procedure TIdHTTPThread.Disconnect;
begin
idhttp.Disconnect;
end;
procedure TIdHTTPThread.OnWorkEnd(ASender: TObject; AWorkMode: TWorkMode);
begin
Synchronize(ResetProgressBar);
end;
procedure TIdHTTPThread.Updatelabel;
begin
Form1.UpdateLabel(FBytesDone);
end;
procedure TIdHTTPThread.UpdateProgressBar;
begin
Form1.UpdateProgressBar(FProgress);
end;
procedure TIdHTTPThread.InitProgressBar;
begin
Form1.initProgressBar(FWorkCountMax);
end;
procedure TIdHTTPThread.resetProgressBar;
begin
Form1.resetProgressBar;
end;
END.
I have in fact 2 questions:
How can I interrupt the download of a (large) file ? I know that
idhttp.disconnect should do the trick, but I do not know how to use it properly in my thread.
And furthermore: how can I use POST instead of GET?
I need to run this POST in a thread:
{++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
//submit_post
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++}
Procedure submit_post(url_string,EncodedStr,filename:string);
var
aStream: TMemoryStream;
Params: TStringStream;
begin
astream := TMemoryStream.create;
Params := TStringStream.create('');
Form1.IdHTTP.Request.Clear;
Form1.IdHTTP.HandleRedirects := TRUE;
try
with Form1.IdHTTP do
begin
Params.WriteString(EncodedStr);
Request.ContentType := 'application/x-www-form-urlencoded';
Request.Charset := 'utf-8';
try
Response.KeepAlive := False;
Post(url_string, params, astream);
except
on E: Exception do
begin
exit;
end;
end;
end;
astream.WriteBuffer(#0' ', 1);
astream.Position := 0;
astream.SaveToFile(filename);
finally
astream.Free;
Params.Free;
end;
end;