TMemoryStream怎么插入一段数据

Question

有谁知道怎么在一个TMemoryStream中间某个位置插入一段数据吗，原来的流分开成为目标的头尾

Answer 1

copy
copyfrom
write
临时流

Answer 2

procedure SaveToEncryptFile(FileText ,FileName :string);
const
  LogFileID :array[0..3] of AnsiChar ='$XXX';
var
  Instream :TStringStream;
  OutStream, OldStream :TFileStream;
  FileID :array[0..3]of char;begin
  InStream :=TStringStream.Create('');
  try
    if FileExists(FileName) then
    begin
      OldStream :=TFileStream.Create(FileName,fmOpenRead);
      try
        OldStream.Read(FileID,SizeOf(FileID));
        OldStream.Position :=SizeOf(FileID);
        if FileID=LogFileID then
        begin
           AeszDecode(OldStream,Instream);
           Instream.Position :=Instream.Size;
           Instream.WriteString(sLineBreak);
        end;
      finally
        OldStream.Free;
      end;
    end;
    Instream.Position :=Instream.Size;
    Instream.WriteString('-- -------------------------'+sLineBreak);
    Instream.WriteString('-- '+FormatDateTime('YYYY-MM-DD hh:mm:ss',Now,fs)+sLineBreak);
    Instream.WriteString('-- -------------------------'+sLineBreak);
    Instream.WriteString(FileText);
    Instream.Position :=0;
    OutStream :=TFileStream.Create(FileName,fmCreate);
    try
      OutStream.Write(LogFileID,SizeOf(LogFileID));
      OutStream.Position :=SizeOf(LogFileID);
      AeszEncode(InStream,OutStream);
    finally
      OutStream.Free;
    end;
  finally
    InStream.Free;
  end;
end;
这个是胡写的，就是执行出错了，自动将SQL放入错误日志，便于给别人支持，SQL包含很多关键逻辑，不想让人看，我加密了。原理就是：如果存在，先解密，加入日期，加入内容，保存。