Implement way to ignore if already downloaded or is completed

[edelciomolina]

Create a way that we can decide if the files already downloads (since really fully completed) have to be downloaded again or not. I noted on some tests that the download always starts again.

Ideas:

• Check local file header "last-modified" and compare with the remote file is newer.
• Check local file header "content-length" and compare with the remote file to know it was download correctly.

[minhnhut]

hi @edelciomolina

Thank you very much for your idea. Hmm, I think it is more complicated than it sounds.

Currently I am working on #1, to add ability to stop downloading completely, and then resume later.
And I am also working on file name conflict resolving, which might happen when DownloadWorker try to finish up - joining files (Other file with same name as downloading file exists, etc.)

I am going to introduce some more options to allow customize DownloadWorker's strategy when file name conflict happened. Some strategies may be:

• Skip it, do nothing
• Same name, with increment number suffix like Windows/Macosx do: Filename (1).docx, Filename (2).docx, etc.

Other than that, I would like to leave it to userland, to handle if they really want to download file again, or skip it. Maybe by checking file "last-modified" or "content-length" as you said. But I doubt it, because:

• "last-modified" is a optional cache control header, not all site and its resource include this in header.
• "content-length" is hard to judge if file is same. For example, two .txt file with content: "File" and "file" will have same content-length.