aimed to tell you how to upload file by using bootstrap-fileinput and how to read it online by using pdf.js
firstly, upload a file named test.pdf
secondly, get new name of this file
then trans address to iframe
finally, you can read it online
there is no auto-trans for file's address in this demo
usage:
run the demo and ask for "127.0.0.1:5000/upload"
select a file(pdf file) to upload
get it's name in /static/doc
change src in iframe(show.html)
ask for "127.0.0.1:5000/show"