Receive a set of bytes over bluetooth?

Question

Java

Hello, the task is to receive a string or bytes to a computer via bluetooth and transfer them to a device connected via a usb port.
The question is by what means this can be done, maybe there is an example in the source code.
Do I need to open a new connection for each new message, or does the bluetooth connection open once and then everything is sent through it.
I managed to find something similar to java, but it worked strange there, an inputstream was opened and messages were constantly read from it, while it was not possible to understand where one message ends and another begins.