Indy TIdTCPClient 接收文本

Question

我尝试在 idtcpclient 中接收文本，但它不起作用。 这是我在计时器中使用的代码：

procedure TForm1.Timer2Timer(Sender: TObject);
var
  receivedtext:string;
begin
  if idtcpclient1.Connected = true then
  begin
    with idtcpclient1 do
    begin
      if not IOHandler.InputBufferIsEmpty then
      begin
        try
          receivedtext := IOHandler.ReadLn;
        finally
          if receivedtext = '' = false then
          begin
            showmessage(receivedtext);
            idtcpclient1.IOHandler.InputBuffer.Clear;
            receivedtext := '';
          end;
        end;
      end;
    end;
  end
  else
  begin
    timer2.Enabled := false;
  end;
end;

定时器的间隔为 8 毫秒。 计时器在连接时自动启用。 但是当我发送一些东西时，我没有收到消息框或错误。 我确信我写了数据，因为当我使用tclientsocket我确实收到了它。

我做错了什么？

Answer 1

使用更像这样的东西：

procedure TForm1.Timer2Timer(Sender: TObject);
var
  receivedtext: string;
begin
  with IdTCPClient1 do
  begin
    try
      if IOHandler.InputBufferIsEmpty then
      begin
        IOHandler.CheckForDataOnSource(0);
        IOHandler.CheckForDisconnect;
        if IOHandler.InputBufferIsEmpty then Exit;
      end;
      receivedtext := IOHandler.ReadLn;
    except
      Timer2.Enabled := False;
      Exit;
    end;
    if receivedtext <> '' then
      ShowMessage(receivedtext);
  end;
end;

话虽如此，这种代码最好使用工作线程而不是计时器来实现。

1 - 创建一个从TThread派生的新类（文件 > 新建 > 其他 > 线程对象）

type
  TDataEvent = procedure(const Data: string) of object;

  TReadingThread = class(TThread)
  private
    FClient: TIdTCPClient;
    FData: string;
    FOnData: TDataEvent;
    procedure DataReceived;
  protected
    procedure Execute; override;
  public
    constructor Create(AClient: TIdTCPClient); reintroduce;
    property OnData: TDataEvent read FOnData write FOnData;
  end;

constructor TReadingThread.Create(AClient: TIdTCPClient);
begin
  inherited Create(True);
  FClient := AClient;
end;

procedure TReadingThread.Execute;
begin
  while not Terminated do
  begin
    FData := FClient.IOHandler.ReadLn;
    if (FData <> '') and Assigned(FOnData) then
      Synchronize(DataReceived);
  end;
end;

procedure TReadingThread.DataReceived;
begin
  if Assigned(FOnData) then
    FOnData(FData);
end;

2 - 修改您的连接代码：

IdTCPClient1.Connect;
try
  Thread := TReadingThread.Create(IdTCPClient1);
  Thread.OnData := DataReceived;
  Thread.Resume;
except
  IdTCPClient1.Disconnect;
  raise;
end;

...

if Assigned(Thread) then Thread.Terminate;
try
  IdTCPClient1.Disconnect;
finally
  if Assigned(Thread) then
  begin
    Thread.WaitFor;
    FreeAndNil(Thread);
  end;
end;

...

procedure TForm1.DataReceived(const Data: string);
begin
  ShowMessage(Data);
end;