修改 Android 5.x 系统默认音量大小

修改系统默认音量需要改两处地方：

1. 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
         8,//11, // STREAM_MUSIC
         6,  // STREAM_ALARM
         5,  // STREAM_NOTIFICATION
         7,  // STREAM_BLUETOOTH_SCO
         7,  // STREAM_SYSTEM_ENFORCED
         11, // STREAM_DTMF
         11,  // STREAM_TTS
         4   // STREAM_INCALL_MUSIC
     };

此处的音量值用来生成settings.db数据库字段的值。settings.db数据库在Android 5.x中的路径为/data/data/com.android.providers.settings/database/目录下。

2. frameworks\base\media\java\android\media\AudioService.java

 /** @hide Maximum volume index values for audio streams */
     private static int[] MAX_STREAM_VOLUME = new int[] {
         15,  // STREAM_VOICE_CALL
         7,  // STREAM_SYSTEM
         7,  // STREAM_RING
         15, // STREAM_MUSIC
         7,  // STREAM_ALARM
         7,  // STREAM_NOTIFICATION
         15, // STREAM_BLUETOOTH_SCO
         7,  // STREAM_SYSTEM_ENFORCED
         15, // STREAM_DTMF
         15  // STREAM_TTS
     };
 
     private static int[] DEFAULT_STREAM_VOLUME = new int[] {
         15,  // STREAM_VOICE_CALL
         7,  // STREAM_SYSTEM
         5,  // STREAM_RING
         8,//11, // STREAM_MUSIC
         6,  // STREAM_ALARM
         5,  // STREAM_NOTIFICATION
         7,  // STREAM_BLUETOOTH_SCO
         7,  // STREAM_SYSTEM_ENFORCED
         11, // STREAM_DTMF
         11  // STREAM_TTS
     };

MAX_STREAM_VOLUME 数组为系统最大音量值。

DEFAULT_STREAM_VOLUME 数组为系统默认音量值。