I built a similar app Shazam, however it only works in sending an entire file of 10seconds of audio.
My doubt is: In android, there's any thing to keep like Shazam of while music is playing and the database is searching? Or it's own Shazam service technology?
On
The Shazam technology is proprietary. The base algorithm was documented since by its creator:
The algorithm uses a combinatorially hashed time-frequency constellation analysis of the audio, yielding unusual properties such as transparency, in which multiple tracks mixed together may each be identified.
This is very novel and efficient, but the principles for fingerprinting audio stay the same. Among which certainly a FTT (fast fourier transform) to at least detect the BPM. Its even possible to convert sound to an image (the simplest being a spectogram), which can be further processed by audio-unrelated software.
If you need an audio analysis library, written in Java you could look into MusicG for example which is said to be simple to use on Android.
Shazam developed that audio fingerprint matching technlogy. It's not available in the default Android SDK.