File transfer in java?

Question

Java

How to correctly transfer data from an android application to the server (photo, video, audio, etc.), and receive it from the server, what to learn for this? Speed ​​and safety are important.

Answer 1

The principles of networking, the network protocol stack, in particular the http protocol, Java mechanisms for working with http, popular third-party libraries such as okHttp and Retrofit, and necessarily Android multithreading mechanisms.