indy10的idHttpServer发送流

indy10的idHttpServer发送流

先看源码：

procedure TIdIOHandler.Write(AStream: TStream; ASize: TIdStreamSize = 0;
  AWriteByteCount: Boolean = FALSE);
var
  LBuffer: TIdBytes;
  LStreamPos: TIdStreamSize;
  LBufSize: Integer;
  // LBufferingStarted: Boolean;
begin
  if ASize < 0 then begin //"-1" All from current position
    LStreamPos := AStream.Position;
    ASize := AStream.Size - LStreamPos;
                                 
    AStream.Position := LStreamPos;
  end
  else if ASize = 0 then begin //"0" ALL
    ASize := AStream.Size;
    AStream.Position := 0;
  end;
  //else ">0" number of bytes

  // RLebeau 3/19/2006: DO NOT ENABLE WRITE BUFFERING IN THIS METHOD!
  //
  // When sending large streams, especially with LargeStream enabled,
  // this can easily cause "Out of Memory" errors.  It is the caller's
  // responsibility to enable/disable write buffering as needed before
  // calling one of the Write() methods.
  //
  // Also, forcing write buffering in this method is having major
  // impacts on TIdFTP, TIdFTPServer, and TIdHTTPServer.

  if AWriteByteCount then begin
    if LargeStream then begin
      Write(Int64(ASize));
    end else begin
      {$IFDEF STREAM_SIZE_64}
      if ASize > High(Integer) then begin
        raise EIdIOHandlerRequiresLargeStream.Create(RSRequiresLargeStream);
      end;
      {$ENDIF}
      Write(Int32(ASize));
    end;
  end;

  BeginWork(wmWrite, ASize);
  try
    SetLength(LBuffer, FSendBufferSize);
    while ASize > 0 do begin
      LBufSize := IndyMin(ASize, Length(LBuffer));
      // Do not use ReadBuffer. Some source streams are real time and will not
      // return as much data as we request. Kind of like recv()
      // NOTE: We use .Size - size must be supported even if real time
      LBufSize := TIdStreamHelper.ReadBytes(AStream, LBuffer, LBufSize);
      if LBufSize <= 0 then begin
        raise EIdNoDataToRead.Create(RSIdNoDataToRead);
      end;
      Write(LBuffer, LBufSize);
      // RLebeau: DoWork() is called in WriteDirect()
      //DoWork(wmWrite, LBufSize);
      Dec(ASize, LBufSize);
    end;
  finally
    EndWork(wmWrite);
    LBuffer := nil;
  end;
end;

　　

const
  GRecvBufferSizeDefault = 32 * 1024;
  GSendBufferSizeDefault = 32 * 1024;

　　如果流数据大于32K，会分成多包发送，每包最大32K。