Android 设置声音时出现按键音

static AudioManager tMyAudioManager;

tMyAudioManager = (AudioManager) tMyContext.getSystemService(Context.AUDIO_SERVICE);

tMyAudioManager.setStreamVolume(AudioManager.STREAM_MUSIC, tInputVal, AudioManager.FLAG_PLAY_SOUND);

每次调用setStreamVolume时都会出现按键音，查了一下AudioMabager.java后来发现是第三个参数的原因

 public static final int FLAG_PLAY_SOUND = 1 << 2;

    /**
     * Removes any sounds/vibrate that may be in the queue, or are playing (related to
     * changing volume).
     */
    public static final int FLAG_REMOVE_SOUND_AND_VIBRATE = 1 << 3;

    /**
     * Whether to vibrate if going into the vibrate ringer mode.
     */
    public static final int FLAG_VIBRATE = 1 << 4;

    /**
     * Indicates to VolumePanel that the volume slider should be disabled as user
     * cannot change the stream volume
     * @hide
     */
    public static final int FLAG_FIXED_VOLUME = 1 << 5;

    /**
     * Ringer mode that will be silent and will not vibrate. (This overrides the
     * vibrate setting.)
     *
     * @see #setRingerMode(int)
     * @see #getRingerMode()
     */
    public static final int RINGER_MODE_SILENT = 0;

    /**
     * Ringer mode that will be silent and will vibrate. (This will cause the
     * phone ringer to always vibrate, but the notification vibrate to only
     * vibrate if set.)
     *
     * @see #setRingerMode(int)
     * @see #getRingerMode()
     */
    public static final int RINGER_MODE_VIBRATE = 1;

    /**
     * Ringer mode that may be audible and may vibrate. It will be audible if
     * the volume before changing out of this mode was audible. It will vibrate
     * if the vibrate setting is on.
     *
     * @see #setRingerMode(int)
     * @see #getRingerMode()
     */
    public static final int RINGER_MODE_NORMAL = 2;

    // maximum valid ringer mode value. Values must start from 0 and be contiguous.
    private static final int RINGER_MODE_MAX = RINGER_MODE_NORMAL;

    /**
     * Vibrate type that corresponds to the ringer.
     *
     * @see #setVibrateSetting(int, int)
     * @see #getVibrateSetting(int)
     * @see #shouldVibrate(int)
     * @deprecated Applications should maintain their own vibrate policy based on
     * current ringer mode that can be queried via {@link #getRingerMode()}.
     */
    public static final int VIBRATE_TYPE_RINGER = 0;

    /**
     * Vibrate type that corresponds to notifications.
     *
     * @see #setVibrateSetting(int, int)
     * @see #getVibrateSetting(int)
     * @see #shouldVibrate(int)
     * @deprecated Applications should maintain their own vibrate policy based on
     * current ringer mode that can be queried via {@link #getRingerMode()}.
     */
    public static final int VIBRATE_TYPE_NOTIFICATION = 1;

    /**
     * Vibrate setting that suggests to never vibrate.
     *
     * @see #setVibrateSetting(int, int)
     * @see #getVibrateSetting(int)
     * @deprecated Applications should maintain their own vibrate policy based on
     * current ringer mode that can be queried via {@link #getRingerMode()}.
     */
    public static final int VIBRATE_SETTING_OFF = 0;

    /**
     * Vibrate setting that suggests to vibrate when possible.
     *
     * @see #setVibrateSetting(int, int)
     * @see #getVibrateSetting(int)
     * @deprecated Applications should maintain their own vibrate policy based on
     * current ringer mode that can be queried via {@link #getRingerMode()}.
     */
    public static final int VIBRATE_SETTING_ON = 1;

    /**
     * Vibrate setting that suggests to only vibrate when in the vibrate ringer
     * mode.
     *
     * @see #setVibrateSetting(int, int)
     * @see #getVibrateSetting(int)
     * @deprecated Applications should maintain their own vibrate policy based on
     * current ringer mode that can be queried via {@link #getRingerMode()}.
     */
    public static final int VIBRATE_SETTING_ONLY_SILENT = 2;

    /**
     * Suggests using the default stream type. This may not be used in all
     * places a stream type is needed.
     */
    public static final int USE_DEFAULT_STREAM_TYPE = Integer.MIN_VALUE;