修改此文件frameworks/base/media/java/android/media/AudioService.java中函數

private int getActiveStreamType(int suggestedStreamType) {         
   
　　...............
　　...............
　　 else if (suggestedStreamType == AudioManager.USE_DEFAULT_STREAM_TYPE) {

                /* carroll 修改音量鍵默認調節多媒體音量 start */
                /*
 
   if (isAfMusicActiveRecently(StreamOverride.sDelayMs)) {
                    if (DEBUG_VOL) Log.v(TAG, "getActiveStreamType: forcing STREAM_MUSIC");*/
                    return AudioSystem.STREAM_MUSIC;
                /* } else {
                    if (DEBUG_VOL) Log.v(TAG,
                            "getActiveStreamType: using STREAM_NOTIFICATION as default");
                    return AudioSystem.STREAM_NOTIFICATION;
                }
 
*/
                /* carroll 修改音量鍵默認調節多媒體音量 end */
            }
            break;
        }
        if (DEBUG_VOL) Log.v(TAG, "getActiveStreamType: Returning suggested type "
                + suggestedStreamType);
        return suggestedStreamType;
    }

重新編譯後，按音量鍵提示欄為多媒體音量

android5.1 修改音量鍵綁定多媒體聲音