文件操作问题，如何在文件尾部追新的文件片？

Question

我用indy分片断点传文件，客户端每次发送32K，但是在服务器端接收之后，每次写入都将原来的覆盖了，如何解决？望高手不吝赐教！服务器端处理源码：
  If sCommand='StreamContent' Then
  Begin
    //接收文件大小
    sCommand:=AThread.Connection.ReadLn();
    TotalSize:=StrToInt(sCommand);    //当前大小
    fs:=TFileStream.Create('TestReceive.exe',fmOpenRead);
    NowSize:=fs.Size;
    fs.Free;
    lbRecord.Items.Add(IntToStr(NowSize) + '/' + sCommand);    //接收流
    fs:=TFileStream.Create('TestReceive.exe',fmOpenReadWrite);
    AThread.Connection.ReadStream(fs,Min(TotalSize-NowSize,AThread.Connection.RecvBufferSize),False);
//*******问题就出在上面这行，我换过打开方式为fmCreate，也不行******
    fs.Free;    //发送当前字节大小，如果已经完成，则发送FILEEND
    fs:=TFileStream.Create('TestReceive.exe',fmOpenRead);
    NowSize:=fs.Size;
    If NowSize>=TotalSize Then AThread.Connection.WriteLn('FILEEND') Else
    Begin
      AThread.Connection.WriteLn(IntToStr(NowSize));
    end;
    fs.Free;    //发送提示继续
    AThread.Connection.WriteLn('GOON');
  end;

Answer 1

同问题发送在DELPHI的网络通信版，up者1分，解决者最少50分。

Answer 2

继续哼哼哈哈没有人来，我就来。哼哼哈哈。没有人来，我就来。哼哼哈哈。var
  CurrentFile: TFileStream ;
  NextFile: TFileStream;
  UpdateFile: File;
begin
  //建立一个临时文件
  if FileExists('NextTestReceive.exe') then
  begin
    DeleteFile('NextTestReceive.exe');
    FileCreate('NextTestReceive.exe');
    AssignFile(UpdateFile,'NextTestReceive.exe');
    Rewrite(UpdateFile,1);
    CloseFile(UpdateFile);
  end;  CurrentFile := TFileStream.Create('TestReceive.exe',fmOpenwrite);
  CurrentFile.Seek(0,soFromEnd);  NextFile := TFileStream.Create('NextTestReceive.exe',fmOpenRead);
  AThread.Connection.ReadStream(NextFile, -1, True);//读
  NextFile.Seek(0, soFromBeginning);  CurrentFile.CopyFrom(NextFile, NextFile.Size); //追尾  CurrentFile.Free;
  NextFile.Free;
end;

Answer 3

//建立一个临时文件
  if FileExists('NextTestReceive.exe') then
    DeleteFile('NextTestReceive.exe');    FileCreate('NextTestReceive.exe');
    AssignFile(UpdateFile,'NextTestReceive.exe');
    Rewrite(UpdateFile,1);
    CloseFile(UpdateFile);