Delphi窗体多实例使用(delphi Form with multi instance use)

我已经使用在运行时创建开始上传到多个FTP服务器（使用印）形式的FTP上传的项目，我的问题如下（我真的需要你的帮助）。

在窗体上，我把一个IdFTP组件+的上传按钮+公共属性命名FTPSrvAdrs和SRCFILE + TrgFolder像这样：

type
  TFtpUploader = class(TForm)
    IdFTP: TIdFTP;
    StartUpload:TButton;
    UploadProgress:TProgressBar;
    procedure StartUploadClick(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
  private
    FFtpSrvAdrs:String;
    FSrcFile:String;
    FTargetFtpFld:String;
    Procedure StartMyUpload();
    procedure SetFtpAdrs(const value:string);
    procedure SetSrcFile(const value:string);
    procedure SetTargetFtpFld(const value:string);
    { Private declarations }
  public
    { Public declarations }
    property FtpAdrs:string read FFtpSrvAdrs write SetFtpAdrs;
    property SourceFile:string read FSrcFile write SetSrcFile;
    property TargetFtpFld:string read FTargetFtpFld write SetTargetFtpFld;
  end;

var
  FtpUploader: TFtpUploader;

implementation

  procedure TFtpUploader.StartUploadClick(Sender: TObject);
  begin
  StartMyUpload(); 
  end;

  procedure TFtpUploader.SetFtpAdrs(const value: string);
  begin
  FFtpSrvAdrs:=value;
  end;

  procedure TFtpUploader.SetSrcFile(const value: string);
   begin
   FSrcFile:=value;
  end;

  procedure TFtpUploader.SetTargetFtpFld(const value: string);
   begin
  FTargetFtpFld:=value;
   end;

   procedure TFtpUploader.StartMyUpload;
    var
    FtpUpStream: TFileStream;
    begin
      ftpUpStream:= TFileStream.create(FSrcFile, fmopenread)
     try
     with IdFTP do begin
      Host:= FFtpSrvAdrs;
      Username:='MyUserName';
      Password:='MyPassword';
    end;
    IdFTP.Connect(true, 1200)
    IdFTP.Passive:= true;
    IdFTP.ChangeDir(FTargetFtpFld)
    IdFTP.Put(ftpUpStream,FSrcFile, false);
   finally
   ftpUpStream.Free;
   end;
   end;


  procedure TFtpUploader.FormClose(Sender: TObject; var Action: TCloseAction);
  begin
  Action:=caFree;
  end;

此表将在运行时创建（4倍= 4个按键将分别推出像这样：

在主窗体我这个程序：

    Procedure MainForm.UploadTo(FTPSrv,SrcFile,FtpTargetFld:String);
        var
         FUploadFrm:TFtpUploader;
         begin
          FUploadFrm:=TFtpUploader.Create(nil);
          if assigned(FUploadFrm) then
         begin
          FUploadFrm.FtpAdrs:=FTPSrv;
          FUploadFrm.SourceFile:=SrcFile;
          FUploadFrm.TargetFtpFld:=FtpTargetFld;
          FUploadFrm.Show;
         end;
         end;

        procedure MainForm.Button1Click(Sender: TObject);
         begin
        UploadTo('MyFtpSrv_1','MySrcFile_1','MyFtpTargetFld_1');
        end;

         procedure MainForm.Button2Click(Sender: TObject);
         begin
         UploadTo('MyFtpSrv_2','MySrcFile_2','MyFtpTargetFld_2');
         end;

// same with other 2 buttons

该FtpUploader创建窗体/开业（4例），问题是当我点击StartUpload按钮，FTP上传过程不是在所有这些4个实例开始，但我已经等待每个上传过程完成（完成）和另将自动启动，这意味着并不是所有的上传过程在同一时间开始。

谢谢 。

Answer 1:

看来你必须要么改变印库对于一些无阻塞的背景库（基于基于事件或完成端口），或使你的程序多线程（与它自己的一堆像用户问题点击一个按钮，20倍或闭形式，而该过程将会，或即使在关闭上运行的程序）。

基于http://otl.17slon.com/book/doku.php?id=book:highlevel:async它可以看看这样的事：

  TFtpUploader = class(TForm)
  private
    CanCloseNow: boolean;

...

  procedure TFtpUploader.FormClose(Sender: TObject; var Action: TCloseAction);
  begin
    if Self.CanCloseNow
       then Action := caFree
       else Action := caIgnore;
  end;

  procedure TFtpUploader.MyUploadComplete;
  begin
    Self.CanCloseNow := True;
    Self.Close;
  end;

  procedure TFtpUploader.StartMyUpload;
  begin
    Self.CanCloseNow := false;
    Self.Enabled := False;
    Self.Visible := True;
    Application.ProcessMessages;

Parallel.Async(
  procedure
    var
    FtpUpStream: TFileStream;
    begin
     ftpUpStream:= TFileStream.create(FSrcFile, fmopenread)
     try
      with IdFTP do begin
       Host:= FFtpSrvAdrs;
       Username:='MyUserName';
       Password:='MyPassword';
       Connect(true, 1200)
       Passive:= true;
       ChangeDir(FTargetFtpFld)

       // this does not return until uploaded
       // thus would not give Delphi a chance to process buttons 
       //    pressed on other forms.
       Put(ftpUpStream,FSrcFile, false);
     end; 
    finally
      ftpUpStream.Free;
    end;
   end
,
  Parallel.TaskConfig.OnTerminated(
    procedure (const task: IOmniTaskControl)
    begin
      MyUploadComplete;
    end;
);
end;

或者你可以使用simplier AsyncCalls库http://andy.jgknet.de/blog/bugfix-units/asynccalls-29-asynchronous-function-calls/

文章来源: delphi Form with multi instance use