Since there is no standard OBEX OPP / FTP method / implementation that is provided to Android developers, you will have to turn you over to the Bluetooth API , which is quite powerful, implements almost any protocol you want, since it reflects TCP sockets.
The first thing you need to do is access the file system. Assuming the SD card here is a guide, otherwise you need root access. Then you want to establish a Bluetooth connection between the two devices (pattern code). Finally, you must Google configure the protocol specification for OBEX OPP / FTP and implement it, which is likely to take longer.
I am sure that other applications on the market do this because they require applications on both devices to send / receive files and view the file system. I can not deeply understand the OBEX protocol, because I am not familiar with it, but I can tell in detail about everything that is needed, if necessary. However, a Google search turned out to be this one , which may be useful in implementation.
Not sure if this will help, but I saw this one to work with a lot of people to send files.
Jasoneer
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