求助:关于线程的问题

Question

我写了一个线程,用来检测我们终端上面设备的工作状态.每次启动程序的时候就把这个线程起来,但线程一起来,我程序的窗口就没有响应了.如果不起线程,这个窗口是正常的.第一次用DELPHI,搞不清楚怎么回事.大家能不能帮我分析下.

Answer 1

启动程序后，隔一会再启动线程看看，用一个Button测试一下。

Answer 2

unit UDetectCard;interface
uses
    windows,Classes,SysUtils,Face_public,variable,forms,Dialogs;
type
    TDetectCardThread = class(TThread)
    private
      { Private declarations }
    protected
      procedure Execute; override;
    public
      IsWorking: Boolean;
      Trantype:  Integer;
      LogFlag:   Integer;
      RetCode:   Integer;
      constructor Create;
    end;    function CreateDetectCardThread: Boolean;
    function ResumeDetectCardThread: Boolean;
    function FreeDetectCardThread: Boolean;
    function DetectCard:Boolean;
//    function GetMagTrack(TrackData:PChar;Track2:PChar;Track3:PChar):Boolean;
var
    DetectCardThread:TDetectCardThread;
implementation
uses
    processMain,udll;function CreateDetectCardThread: Boolean;
begin
  ShowMessage('线程开启');
  Result := False;
  if ( DetectCardThread = nil ) then
  begin
    DetectCardThread := TDetectCardThread.Create;
    DetectCardThread.Execute;
    Result := True;
  end;
end;function ResumeDetectCardThread: Boolean;
begin
  Result := False;
  if ( DetectCardThread = nil ) then
    Exit;  DetectCardThread.Resume;
  DetectCardThread.IsWorking := true;  Result := True;
end;function FreeDetectCardThread: Boolean;
begin
  Result := False;
  if ( DetectCardThread = nil ) then
    Exit;  DetectCardThread.Terminate;
  while not DetectCardThread.Terminated do
    Application.ProcessMessages;  try
  if ( DetectCardThread <> nil ) then       
  begin
    DetectCardThread.Free;
    DetectCardThread := nil;
  end;  Result := True;
  except
    DetectCardThread := nil;
  end;
end;constructor TDetectCardThread.Create;
begin
  IsWorking := false;  inherited Create(true);  //don‘t execute
end;procedure TDetectCardThread.Execute;
var
    i:Integer;
begin
      i := 0;
      while i = 0 do
      begin
        DetectCard;
      end;end;function DetectCard:Boolean;
var
    i,Track2Pos,Track3Pos,len,ErrCount:integer;
    bReadMode,bReadTrack:BYTE;
    szTrackData:array [0..160] of char;
    szTrack2,szTrack3:string;
    PHasCard,PAllowCardIn:array [0..1] of char;begin
    ErrCount := 0;
    Result := FALSE;
    if  gComHandle = 0 then
        ErrLog(gErrLogPath,'磁条卡串口未被初始化', 5);
//        ShowMessage('磁条卡串口未被初始化');
    PAllowCardIn[0] := char($0);
    i := CRT386_GetStatus(gComHandle,PHasCard, PAllowCardIn);
    if i = 0 then
    begin
//        ShowMessage('读取是否有卡成功');
        if gCardState = 0 then
        begin
            if PHasCard[0] = char($1) then
            begin
//               ShowMessage('读卡器插卡');
               gCardState := 1;
               i := 0;
               i := CRT_IC_CardOpen(gComHandle);
               if i = 0 then
                  ErrLog(gErrLogPath,'上电成功', 5);
  //                ShowMessage('上电成功');
               i := 0;
               i := AT88SC102_Reset(gComHandle);
               if i = 0 then
               begin
                  ShowMessage('复位成功');
                  ErrLog(gErrLogPath,'IC卡复位成功，判断为煤气卡', 5);
                  if(PostMessage(Controlfrm.handle,WM_MQCARD_IN,0,0))  then
                        ShowMessage('发送煤气卡消息成功');
               end
               else
               begin                  i := 0;
                  bReadMode := $30;
                  bReadTrack := $35;
                  i := MC_ReadTrack(gComHandle,bReadMode,bReadTrack,szTrackData);
                  if i = 0 then
                  begin
                      Len := sizeof(szTrackData);
                              i := 5;
                      for i:= 5 to Len-1 do
                      begin
                      if szTrackData[i] = char($1F) then
                        begin
                          Track3Pos := i;
                          break;
                        end;
                      end;                      Track2Pos := 5;
                      if szTrackData[4] = char($59) then
                      begin
                      szTrack2 := copy(String(szTrackData),6,(Track3Pos-Track2Pos));
                      end else
                      begin
                          ErrLog(gErrLogPath,'无二磁信息或读取失败', 5);
                          Inc(ErrCount);
//                          ShowMessage('无二磁信息或读取失败');
                      end;
                      if szTrackData[Track3Pos+1] = char($59) then
                      begin
                          szTrack3 := copy(String(szTrackData),Track3Pos+3,104);
                      end else
                      begin
                          ErrLog(gErrLogPath,'无三磁信息或读取失败', 5);
                          Inc(ErrCount);
//                          ShowMessage('无三磁信息或读取失败');
                      end;
                      if ErrCount>= 2 then
                      begin
                          PostMessage(Controlfrm.handle,WM_ReadCardFail,0,0);
//                          ShowMessage('发送失败消息');
                      end
                      else begin
                          ShowMessage('发送成功消息');
                          if(PostMessage(Controlfrm.handle,WM_ReadCardSuccess,WPARAM(szTrack2),LPARAM(szTrack3)))  then
//                              ShowMessage('消息发送成功');
                      end;
                      sleep(500);
//                     ShowMessage(szTrack2);
//                      ShowMessage(szTrack3);
                  end
                  else begin
                      ErrLog(gErrLogPath,'读取磁条卡失败', 5);
//                      ShowMessage('读取磁条卡失败');
                  end;
               end;
            end;// else
            //   ShowMessage('无动作1');
        end else
        begin
            if PHasCard[0] = char($1) then
//               ShowMessage('无动作1');
            else begin
               gCardState := 0;
//               ShowMessage('读卡器退卡');
            end;
        end;
    end;end;
end.
这个是我线程的代码,窗口的代码以前别人写的,比较大,先不发了.我在程序一开始的时候就调用CreateDetectCardThread.或者在一个按钮里面开启这个线程,都会使窗口没响应了,鼠标点不到上面的按钮

Answer 3

线程中最好不要用ShowMessage,如果非用不可,最好是在主线程中执行,
线程中,最好也不要用Application.ProcessMessages.

Answer 4

比较喜欢用  CreateThread这样子线程 与 主线程 通过 消息或其他方式来通信没啥的。

Answer 5

线程中涉及到窗体操作的，都要用Synchronize(yourfunc)进行同步，否则可能会造成窗体会冻结，showmessage就存在这个问题。

Answer 6

Execute中加上一条sleep(50);否则CPU占用率可能会狂高。

Answer 7

procedure TDetectCardThread.Execute;
begin
  while not Terminated do begin
    DetectCard;
    sleep(50);
  end;
end;

Answer 8

你在主线程调用Execute？
那你这就失去线程的意义了，你这是单线程的。

Answer 9

还有一个问题想请教大家
PostMessage(Controlfrm.handle,WM_ReadCardFail,0,0);
ErrLog(gErrLogPath,'读取卡片磁条信息失败', 5);
ShowMessage('读取失败');
如果我把ShowMessage这句注释掉的话,PostMessage发出的消息,ControlFrm就收不到这个消息,如果ShowMessage没注释掉,ControlFrm就能收到该消息