Android: 系统默认音量

frameworks\base\media\java\android\media\AudioManager.java    /**  @hide Default volume index values for audio streams */    public static final int[] DEFAULT_STREAM_VOLUME = new int[] {        4,  // STREAM_VOICE_CALL        7,  // STREAM_SYSTEM        5,  // STREAM_RING        11, // STREAM_MUSIC        6,  // STREAM_ALARM        5,  // STREAM_NOTIFICATION        7,  // STREAM_BLUETOOTH_SCO        7,  // STREAM_SYSTEM_ENFORCED        11, // STREAM_DTMF        11  // STREAM_TTS    };