如何使用IdTCPClient从服务器等待字符串？ [英] How can I wait for a string from a server with IdTCPClient?

问题描述

我有一个IdTelnet（indy 10.1）的问题。我无法以Unicode模式从服务器读取数据。现在我想用IdTCPClient编写telnet终端。

I have a problem with IdTelnet (indy 10.1). I can't read the data from a server in Unicode mode. and now I want to write the telnet terminal with IdTCPClient.

服务器有时发送一行，有时候会发送越来越多的行。但是发送之间没有固定的时间。

The server sometimes send one line and sometimes more and more lines. But there is not a fixed time between sending.

现在我的问题是，当我必须从InBuffer读取数据。

Now my problem is that when I must read data from InBuffer.

或者当我必须使用ReadLn函数从服务器读取数据时，必须运行多少次ReadLn？

Or when I must use the ReadLn function to read the data from the server, how many times must I run the ReadLn?

推荐答案

TIdTelnet 是一个多线程组件。它有一个内部线程，从套接字连续读取，每当数据缓冲区可用时触发 TIdTelnet.OnDataAvailable 事件。

TIdTelnet is a multithreaded component. It has an internal thread that continuously reads from the socket, firing the TIdTelnet.OnDataAvailable event whenever a buffer of data is available.

TIdTelnet 是一个 TIdTCPClient 后裔。查看IdTelnet.pas源文件，看看它是如何实现的。您可以在自己的代码中执行类似的操作，在您自己的线程中调用 TIdIOHandler.ReadLn（），例如：

TIdTelnet is a TIdTCPClient descendant. Look in the IdTelnet.pas source file to see how it is implemented. You can do something similar in your own code, calling TIdIOHandler.ReadLn() in your own thread, eg:

type
  TMyThread = class(TThread)
  private
    FConn: TIdTCPConnection;
  protected
    procedure Execute; override;
  public
    constructor Create(AConn: TIdTCPConnection); reintroduce;
  end;

constructor TMyThread.Create(AConn: TIdTCPConnection);
begin
  inherited Create(False);
  FConn := AConn;
end;

procedure TMyThread.Execute;
var
  S: String;
begin
  while not Terminated do
  begin
    S := FConn.IOHandler.ReadLn(...);
    ...
  end;
end;

var
  Thread: TMyThread = nil;

procedure TForm1.ConnectButtonClick(Sender: TObject);
begin
  IdTCPClient1.Connect;
  try
    Thread := TMyThread.Create(IdTCPClient1);
  except
    IdTCPClient1.Disconnect;
    raise;
  end;
end;

procedure TForm1.DisconnectButtonClick(Sender: TObject);
begin
  if Assigned(Thread) then Thread.Terminate;
  try
    IdTCPClient1.Disconnect;
  finally
    if Assigned(Thread) then
    begin
      Thread.WaitFor;
      FreeAndNil(Thread);
    end;
  end;
end;

如果不想使用线程，可以使用计时器。为了确保您的定时器线程（如主线程）不被不必要地被阻止，只要 TIdIOHandler.CheckForDataOnSource（） > TIdIOHandler.InputBuffer 是空的，然后在数据可用之前调用 TIdIOHandler.ReadLn（），例如：

If you don't want to use a thread, then you can use a timer instead. To make sure your timer thread (such as the main thread) is not blocked unnecessarily, use the TIdIOHandler.CheckForDataOnSource() method with a small timeout whenever the TIdIOHandler.InputBuffer is empty, before then calling TIdIOHandler.ReadLn() only when data is available, eg:

procedure TForm1.ConnectButtonClick(Sender: TObject);
begin
  IdTCPClient1.Connect;
  ReadTimer.Enabled := True;
end;

procedure TForm1.DisconnectButtonClick(Sender: TObject);
begin
  ReadTimer.Enabled := False;
  IdTCPClient1.Disconnect;
end;

procedure TForm1.ReadTimerElapsed(Sender: TObject);
var
  S: String;
begin
  if IdTCPClient1.IOHandler.InputBufferIsEmpty then
  begin
    IdTCPClient1.IOHandler.CheckForDataOnSource(10);
    if IdTCPClient1.IOHandler.InputBufferIsEmpty then Exit;
  end;
  S := IdTCPClient1.IOHandler.ReadLn(...);
  ...
end;

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