flag 参数是什么意思以及 droid 设备可能的最小值和最大值的范围是多少

Question

1. 我想知道什么是标志（或者可能的值是什么？ 标志）在

   audiomanager.setStreamVolume (int streamType, int index, int flags);

2. 我知道我们可以使用

   audiomanger.getMaxStream(audioManager.getStreamMax(AudioManager.STREAM_MUSIC));

但在某些设备中它给出 13,15，这取决于 Android 版本或设备硬件以及它的范围（最小可能值，最大可能值）

为特定流设置音量索引。

如果设备实现了由 isVolumeFixed() 指示的固定卷策略，则此方法无效。//这是什么意思。

参数

streamType  The stream whose volume index should be set.

index   The volume index to set. See getStreamMaxVolume(int) for the largest valid value.

flags   One or more flags. // what are these flags 

Answer 1

关于标志参数： AudioManager.java 中定义了一些标志。 您可以使用其中任何一种来获得所需的效果。 示例：

audioManager.setStreamVolume(audioManager.STREAM_MUSIC,progress,AudioManager.FLAG_SHOW_UI);

或者干脆

audioManager.setStreamVolume(audioManager.STREAM_MUSIC,progress,1);

这里是来自 AudioManager.java 的代码段，显示了它们是如何定义的。

public static final int FLAG_SHOW_UI = 1 << 0;

/**
 * Whether to include ringer modes as possible options when changing volume.
 * For example, if true and volume level is 0 and the volume is adjusted
 * with {@link #ADJUST_LOWER}, then the ringer mode may switch the silent or
 * vibrate mode.
 * <p>
 * By default this is on for the ring stream. If this flag is included,
 * this behavior will be present regardless of the stream type being
 * affected by the ringer mode.
 *
 * @see #adjustVolume(int, int)
 * @see #adjustStreamVolume(int, int, int)
 */
public static final int FLAG_ALLOW_RINGER_MODES = 1 << 1;

/**
 * Whether to play a sound when changing the volume.
 * <p>
 * If this is given to {@link #adjustVolume(int, int)} or
 * {@link #adjustSuggestedStreamVolume(int, int, int)}, it may be ignored
 * in some cases (for example, the decided stream type is not
 * {@link AudioManager#STREAM_RING}, or the volume is being adjusted
 * downward).
 *
 * @see #adjustStreamVolume(int, int, int)
 * @see #adjustVolume(int, int)
 * @see #setStreamVolume(int, int, int)
 */
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;

/**
 * Indicates the volume set/adjust call is for Bluetooth absolute volume
 * @hide
 */
public static final int FLAG_BLUETOOTH_ABS_VOLUME = 1 << 6;

/**
 * Adjusting the volume was prevented due to silent mode, display a hint in the UI.
 * @hide
 */
public static final int FLAG_SHOW_SILENT_HINT = 1 << 7;

/**
 * Indicates the volume call is for Hdmi Cec system audio volume
 * @hide
 */
public static final int FLAG_HDMI_SYSTEM_AUDIO_VOLUME = 1 << 8;

/**
 * Indicates that this should only be handled if media is actively playing.
 * @hide
 */
public static final int FLAG_ACTIVE_MEDIA_ONLY = 1 << 9;

/**
 * Like FLAG_SHOW_UI, but only dialog warnings and confirmations, no sliders.
 * @hide
 */
public static final int FLAG_SHOW_UI_WARNINGS = 1 << 10;

/**
 * Adjusting the volume down from vibrated was prevented, display a hint in the UI.
 * @hide
 */
public static final int FLAG_SHOW_VIBRATE_HINT = 1 << 11;

/**
 * Adjusting the volume due to a hardware key press.
 * @hide
 */
public static final int FLAG_FROM_KEY = 1 << 12;