现在是这样的：

procedure TForm1.ServerExecute(AThread: TIdPeerThread);
var
  cmd: string; //接收到客户端的字符串信息
  ASize: Integer; //需要传输的流大小
  FileName:string;
  OSVersion:integer;
  path:string;
  ip:string;
  VersionPath: string; //文件路径，在各版本的文件夹下

begin

  ip := AThread.Connection.Socket.Binding.PeerIP;
  with AThread.Connection do
  begin
    cmd := UpperCase(ReadLn);  

    if LeftStr(cmd,5) = 'BEGIN' then  //开始传输  cmd命令格式(BEGIN:操作系统类型(两位数字):文件名)
    begin
      OSVersion := strtoint(MidStr(cmd, 7, 2)); //OSVersion格式(XP以3开头,如31，33)
      case OSVersion of
      31: VersionPath := 'XPsp1';
      32: VersionPath := 'XPsp2';
      33: VersionPath := 'XPsp3';
      41: VerSionPath := 'Vista';
      51: VerSionPath := 'Win7';
      62: VerSionPath := '2003sp2';
      //...
      end;
      FileName := MidStr(cmd, 10, 128);
      tdlcslog('3:'+ip+' 请求文件名为 ' + VersionPath + '\' + FileName);
      Path := ExtractFilePath(Application.ExeName)
              + 'SysFile\' + VersionPath + '\'+FileName;
      if FileExists(Path) then
      begin
        try
                  
          FileStream := TFileStream.Create(Path,fmOpenRead);//全局变量
          //告诉远程传输文件的大小和文件名
          WriteLn(inttostr(FileStream.Size)+'|'+FileName);
          tdlcslog('4:'+ip+' 文件大小 ' + inttostr(FileStream.Size)+'|'+FileName);
         
          //ProgressBar1.Max := FileStream.Size;
          //ProgressBar1.Position := 0;
        except
        end;
      end else
      begin
        WriteLn('-1');
        tdlcslog('4:'+ip+' 文件大小 -1, 文件不存在');
      end;
      Exit;
    end; //end of  if cmd = 'BEGIN'

    if cmd = 'END' then
    begin
      tdlcslog('100:'+ip+' 传输完成');
     
      FileStream.Free;
      //AThread.Stop;
      Exit;
    end;

    if cmd = 'CANCEL' then
    begin
      tdlcslog('99:'+ip+' 传输取消');
     
      FileStream.Free;
      //AThread.Stop;
      Exit;
    end;


    //按照指定位置传输文件
    FileStream.Seek(StrToInt(cmd), soFromBeginning); //转到文件流传输的位置
    ASize := Min(FileStream.Size - FileStream.Position, RecvBufferSize);//计算需要发送的大小，Min()函数在Math单元
    OpenWriteBuffer; //准备发送缓冲
    WriteStream(FileStream, false, false, ASize); //注意这个函数的参数。
    CloseWriteBuffer; //结束发送缓冲
    //StatusBar1.SimpleText := Format('当前传输位置%d/大小%d', [strtoint(cmd)+ASize, FileStream.Size]);
    //ProgressBar1.Position := ProgressBar1.Position + ASize;

   
  end; //end of  with AThread.Connection
end;