1.音频，数据是两个socket连接，
数据传输：基于spp协议（Serial Port Profile）蓝牙设备之间创建串口数据传输的，速率慢
音频传输：基于A2DP协议（Advanced Audio Distribution Profile ）蓝牙音频传输模型协定
http://blog.csdn.net/xzongyuan/article/details/39579435
2.BLE:(android 手机作为gatt server)
learner:http://www.race604.com/gatt-profile-intro/
https://github.com/vir56k/bluetoothDemo
http://www.race604.com/android-ble-tips/
https://www.bluetooth.com/specifications/gatt/services
https://www.quora.com/What-all-Android-phones-support-BLE-peripheral-mode
"BLE peripheral mode is only supported from android Lollipop and above, however not all android devices that have Lollipop support the peripheral mode. For example Nexus 7 and Nexus 5 can be updated to Lollipop but peripheral mode will still not work."
Have a look at the following links for more details about BLE peripheral mode not being supported in the nexus 5 and 7:
- https://code.google.com/p/android-developer-preview/issues/detail?id=1570
- http://stackoverflow.com/questions/26441785/does-bluetoothleadvertiser-work-on-a-nexus-5-with-android-5-0
https://www.androidheadlines.com/2014/06/android-l-brings-ble-peripheral-mode-android.html
BLE 协议分析：http://www.wowotech.net/bluetooth/ble_connection.html
性能：http://blog.csdn.net/chy555chy/article/details/52222982