Delphi

procedure TForm1.IdHTTPServerCommandGet(AContext: TIdContext; ARequestInfo: TIdHTTPRequestInfo; AResponseInfo: TIdHTTPResponseInfo);
var
  FileStream: TFileStream;
begin
  if ARequestInfo.PostStream <> nil then
  begin
    ARequestInfo.PostStream.Position := 0;
    FileStream := TFileStream.Create('1.jpg', fmCreate);
    FileStream.CopyFrom(ARequestInfo.PostStream, ARequestInfo.PostStream.Size); { Copy 流 }
    FileStream.Free;
  end;
end;

参考：

https://blog.csdn.net/zjm12343/article/details/89667560