Delphi：Indy TIdTCPClient讀數據

Question

我正在使用Delphi 2007和Indy 10; 如果我錯過了一些顯而易見的東西，我會有點像德爾福的菜鳥道歉

背景：我有一個簡單的服務器應用程序，只需在連接到其端口時發送單詞“PING”。 如果收到“PONG”字樣，它也會回復。 這工作正常，我已經使用netcat / wireshark手動測試了這個。

我正在嘗試編寫我的客戶端以連接到端口，並在收到它時自動響應PING一詞。 我創建了一個帶有手動連接按鈕的簡單表單。

客戶端連接，但它不響應PING這個詞。 我認為問題在於：

TLog.AddMsg(FConn.IOHandler.ReadLn);

我的調試日志僅報告“DEBUG：TReadingThread.Execute - FConn.Connected”。

我的客戶代碼：

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, IdCustomTransparentProxy, IdSocks, IdBaseComponent,
  IdComponent, IdIOHandler, IdIOHandlerSocket, IdIOHandlerStack,
  IdTCPConnection, IdTCPClient, IdSync;

type

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

  TLog = class(TIdSync)
  protected
    FMsg: String;
  procedure DoSynchronize; override;
  public
    constructor Create(const AMsg: String);
    class procedure AddMsg(const AMsg: String);
  end;


  TForm1 = class(TForm)
    Memo1: TMemo;
    Button1: TButton;
    IdIOHandlerStack1: TIdIOHandlerStack;
    client: TIdTCPClient;
    IdSocksInfo1: TIdSocksInfo;
    procedure Button1Click(Sender: TObject);
    procedure clientConnected(Sender: TObject);
    procedure clientDisconnected(Sender: TObject);
    procedure FormCreate(Sender: TObject);

  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  rt: TReadingThread = nil;

implementation

{$R *.dfm}

constructor TReadingThread.Create(AConn: TIdTCPConnection);
begin
  Form1.Memo1.Lines.Add('DEBUG: TReadingThread.Create'); // Debug

  FConn := AConn;
  inherited Create(False);
end;

procedure TReadingThread.Execute;
begin
  Form1.Memo1.Lines.Add('DEBUG: TReadingThread.Execute'); // Debug

  while not Terminated and FConn.Connected do
  begin
    Form1.Memo1.Lines.Add('DEBUG: TReadingThread.Execute - FConn.Connected'); // Debug

    TLog.AddMsg(FConn.IOHandler.ReadLn);
  end;
end;

constructor TLog.Create(const AMsg: String);
begin
  Form1.Memo1.Lines.Add('DEBUG: TLog.Create'); // Debug

  FMsg := AMsg;
  inherited Create;
end;

procedure TLog.DoSynchronize;
var
  cmd : string;
begin
  Form1.Memo1.Lines.Add('DEBUG: TLog.DoSynchronize'); // Debug

  cmd := copy(FMsg, 1, 1);

  if cmd='PING' then  begin
    Form1.client.Socket.WriteLn('PONG');
  end

end;

class procedure TLog.AddMsg(const AMsg: String);
begin
  Form1.Memo1.Lines.Add('DEBUG: TLog.AddMsg');  // Debug

  with Create(AMsg) do try
    Synchronize;
    finally
    Free;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Memo1.Clear;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  Host : String;
  Port : Integer;
begin

  Host := '127.0.0.1';
  Port := StrToInt('1234');

  client.Host := Host;
  client.Port := Port;

  with client do
  begin
    try
      Connect;
      except
      on E: Exception do
      Memo1.Lines.Add('Error: ' + E.Message);
    end;
  end;

end;

procedure TForm1.clientConnected(Sender: TObject);
begin
  Form1.Memo1.Lines.Add('DEBUG: TForm1.clientConnected'); // Debug

  rt := TReadingThread.Create(client);
end;

procedure TForm1.clientDisconnected(Sender: TObject);
begin
  Form1.Memo1.Lines.Add('DEBUG: TForm1.clientDisconnected');  // Debug

  if rt <> nil then
    begin
      rt.Terminate;
      rt.WaitFor;
      FreeAndNil(rt);
    end;
end;

end.

任何幫助/建議將不勝感激。

謝謝

Answer 1

讀取線程直接訪問Form1.Memo1 ，它不是線程安全的，可能導致死鎖，崩潰，內存損壞等。因此讀取線程甚至可能根本沒有到達ReadLn()調用。 無論訪問實際上多么微不足道，您必須將對UI控件的所有訪問同步到主線程。 只是不要冒險。

此外，您正在TLog本身內部執行線程的ping / pong邏輯，它不屬於它。 更不用說在檢查其值之前將cmd截斷為僅第一個字符，因此它永遠不會檢測到PING命令。 您需要將邏輯移回到它真正屬於的線程中，並刪除截斷。

嘗試這個：

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, IdCustomTransparentProxy, IdSocks, IdBaseComponent,
  IdComponent, IdIOHandler, IdIOHandlerSocket, IdIOHandlerStack,
  IdTCPConnection, IdTCPClient, IdSync;

type

  TReadingThread = class(TThread)
  protected
    FConn: TIdTCPConnection;
    procedure Execute; override;
    procedure DoTerminate; override;
  public
    constructor Create(AConn: TIdTCPConnection); reintroduce;
  end;

  TLog = class(TIdSync)
  protected
    FMsg: String;
    procedure DoSynchronize; override;
  public
    constructor Create(const AMsg: String);
    class procedure AddMsg(const AMsg: String);
  end;

  TForm1 = class(TForm)
    Memo1: TMemo;
    Button1: TButton;
    IdIOHandlerStack1: TIdIOHandlerStack;
    client: TIdTCPClient;
    IdSocksInfo1: TIdSocksInfo;
    procedure Button1Click(Sender: TObject);
    procedure clientConnected(Sender: TObject);
    procedure clientDisconnected(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  rt: TReadingThread = nil;

implementation

{$R *.dfm}

constructor TReadingThread.Create(AConn: TIdTCPConnection);
begin
  TLog.AddMsg('DEBUG: TReadingThread.Create');
  FConn := AConn;
  inherited Create(False);
end;

procedure TReadingThread.Execute;
var
  cmd: string;
begin
  TLog.AddMsg('DEBUG: TReadingThread.Execute');

  while not Terminated do
  begin
    cmd := FConn.IOHandler.ReadLn;
    TLog.AddMsg('DEBUG: TReadingThread.Execute. Cmd: ' + cmd);
    if cmd = 'PING' then begin
      FConn.IOHandler.WriteLn('PONG');
    end
  end;
end;

procedure TReadingThread.DoTerminate;
begin
  TLog.AddMsg('DEBUG: TReadingThread.DoTerminate');
  inherited;
end;

constructor TLog.Create(const AMsg: String);
begin
  inherited Create;
  FMsg := AMsg;
end;

procedure TLog.DoSynchronize;
begin
  Form1.Memo1.Lines.Add(FMsg);
end;

class procedure TLog.AddMsg(const AMsg: String);
begin
  with Create(AMsg) do
  try
    Synchronize;
  finally
    Free;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Memo1.Clear;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  Host : String;
  Port : Integer;
begin
  Host := '127.0.0.1';
  Port := StrToInt('1234');

  client.Host := Host;
  client.Port := Port;

  try
    client.Connect;
  except
    on E: Exception do
      TLog.AddMsg('Error: ' + E.Message);
    end;
  end;
end;

procedure TForm1.clientConnected(Sender: TObject);
begin
  TLog.AddMsg('DEBUG: TForm1.clientConnected');
  rt := TReadingThread.Create(client);
end;

procedure TForm1.clientDisconnected(Sender: TObject);
begin
  TLog.AddMsg('DEBUG: TForm1.clientDisconnected');
  if rt <> nil then
  begin
    rt.Terminate;
    rt.WaitFor;
    FreeAndNil(rt);
  end;
end;

end.

如果仍然不起作用，那么請確保服務器實際上使用CRLF序列或至少一個LF字符（這是默認情況下ReadLn()查找的最小字符）分隔PING字符串。