如何在 Delphi 控制台应用程序中处理 Ctrl+C？

Question

是否有可用的最佳实践和代码片段来展示我如何在 Delphi 控制台应用程序中处理 Ctrl+C？

我找到了一些文章，这些文章提供了一些关于调试器可能出现的问题的信息，包括异常处理、DLL 卸载、标准输入关闭和终结，例如这个 CodeGear 论坛线程。

Answer 1

来自 Windows API（ MSDN ）：

BOOL WINAPI SetConsoleCtrlHandler(
    PHANDLER_ROUTINE HandlerRoutine,    // address of handler function  
    BOOL Add    // handler to add or remove 
   );   

HandlerRoutine function 是控制台进程指定的 function，用于处理进程接收到的控制信号。 function 可以有任何名称。

BOOL WINAPI HandlerRoutine(
    DWORD dwCtrlType    //  control signal type
   );   

---

在 Delphi 中，处理程序例程应如下所示：

function console_handler( dwCtrlType: DWORD ): BOOL; stdcall;
begin
  // Avoid terminating with Ctrl+C
  if (  CTRL_C_EVENT = dwCtrlType  ) then
    result := TRUE
  else
    result := FALSE;
end;

Answer 2

我写了一个小程序来告诉你如何正确地停止后台任务。 希望它更清楚。

ThreadConsoleApplication.dpr 文件的内容：

program ThreadConsoleApplication;

{$APPTYPE CONSOLE}

uses
  SysUtils,
  Windows,
  Classes;

type
  { **
    * Classe TQueueReaderTestApplication
    * }
  TThreadConsoleApplication = class(TThread)
  public
    procedure Execute; override;

    constructor Create; virtual;
    destructor Destroy; override;

    class function getInstance: TThreadConsoleApplication;
  end;

function TThreadConsoleApplication_consoleCtrlHandler(dwCtrlType: DWORD): BOOL;
  stdcall; forward;

{ **
  * Classe TQueueReaderTestApplication
  * }

constructor TThreadConsoleApplication.Create;
begin
  inherited Create(True { CreateSuspended } );
  Windows.setConsoleCtrlHandler(@TThreadConsoleApplication_consoleCtrlHandler,
    True { add } );
end;

var
  threadConsoleApplicationInstance: TThreadConsoleApplication = nil;

destructor TThreadConsoleApplication.Destroy;
begin
  threadConsoleApplicationInstance := nil;
  inherited;
end;

procedure TThreadConsoleApplication.Execute;
begin
  System.Writeln('[TThreadConsoleApplication.Execute] begin');
  try
    while not Terminated do
    begin
      System.Writeln('[TThreadConsoleApplication.Execute] running ...');
      Windows.Sleep(1000 { dwMilliseconds } );
    end;
  finally
    System.Writeln('[TThreadConsoleApplication.Execute] end');
  end;
end;

class function TThreadConsoleApplication.getInstance: TThreadConsoleApplication;
begin
  if nil = threadConsoleApplicationInstance then
  begin
    threadConsoleApplicationInstance := TThreadConsoleApplication.Create;
  end;
  Result := threadConsoleApplicationInstance;
end;

function TThreadConsoleApplication_consoleCtrlHandler(dwCtrlType: DWORD): BOOL;
begin
  Result := False;
  if Windows.CTRL_C_EVENT = dwCtrlType then
  begin
    TThreadConsoleApplication.getInstance.Terminate;
    Result := True;
  end;
end;

var
  thread: TThread;

begin
  System.Writeln('[program] begin');
  try
    thread := nil;
    try
      thread := TThreadConsoleApplication.getInstance;
      thread.Resume;
      System.Writeln('[program] press a CTRL+C to stop running');
      thread.WaitFor;
    finally
      thread.Free;
    end;
    System.Writeln('[program] end');
  except
    on E: Exception do
    begin
      System.Writeln(System.ErrOutput, '[program] end with error');
      System.Writeln(System.ErrOutput, E.ClassName, ': ', E.Message);
    end;
  end;
  System.Writeln('[program] press a key to quit');
  System.Readln;

end.