在安卓手机通话过程中，通过检测音频，判断用户按了哪些键，这个在语音网关处理中非常有用，完全不用硬件！这个是源代码。-In Andrews phone call, by detecting the audio to determine what the user presses a key, the voice gateway processing is very useful, do not need the hardware! This is the source code.