Android 中Notification进度条一直弹出提示及提示音

Android 8.0中Notification的Progress每次更新进度，都会弹出提示，并且有提示音。原代码如下

public void notifyDownloading(long progress, long num, String file_name) {
    Notification.Builder mBuilder;
    mBuilder = new Notification.Builder(MainActivity.this, TAG);
    NotificationChannel channel;
    channel = new NotificationChannel(TAG , file_name, NotificationManager.IMPORTANCE_MAX);
    mNotifyManager.createNotificationChannel(channel);
    mBuilder.setSmallIcon(R.drawable.notification_download_icon);
    mBuilder.setProgress((int) num, (int) progress, false);
    mBuilder.setContentInfo(getPercent((int) progress, (int) num));
    mBuilder.setOngoing(true);
    mBuilder.setWhen(System.currentTimeMillis());
    mBuilder.setContentTitle(file_name);
    mBuilder.setContentText("download");
    PendingIntent pendIntent = PendingIntent.getActivity(
            MainActivity.this, NOTIFY_ID, getCurActivityIntent(), PendingIntent.FLAG_UPDATE_CURRENT);
    mBuilder.setContentIntent(pendIntent);
    mNotifyManager.notify(NOTIFY_ID, mBuilder.build());
}

这里需要修改NotificationChannel的importance属性：

/**
 * Min notification importance: only shows in the shade, below the fold.
 */
public static final int IMPORTANCE_MIN = 1;

/**
 * Low notification importance: shows everywhere, but is not intrusive.
 */
public static final int IMPORTANCE_LOW = 2;

/**
 * Default notification importance: shows everywhere, makes noise, but does not visually
 * intrude.
 */
public static final int IMPORTANCE_DEFAULT = 3;

/**
 * Higher notification importance: shows everywhere, makes noise and peeks. May use full screen
 * intents.
 */
public static final int IMPORTANCE_HIGH = 4;

/**
 * Unused.
 */
public static final int IMPORTANCE_MAX = 5;

这里的IMPORTANCE_MAX应该和IMPORTANCE_HIGH属性类似，表示显示时有声音，且会出现弹框提示。在Android 8.0中，这样设置后，Progress每次更新都会有声音和弹框。

把IMPORTANCE_MAX修改为IMPORTANCE_LOW，则不会出现该现象。

修改后代码如下：

public void notifyDownloading(long progress, long num, String file_name) {
    Notification.Builder mBuilder;
    mBuilder = new Notification.Builder(MainActivity.this, TAG );
    NotificationChannel channel;
    channel = new NotificationChannel(TAG, file_name, NotificationManager.IMPORTANCE_LOW);
    mNotifyManager.createNotificationChannel(channel);
    mBuilder.setSmallIcon(R.drawable.notification_download_icon);
    mBuilder.setProgress((int) num, (int) progress, false);
    mBuilder.setContentInfo(getPercent((int) progress, (int) num));
    mBuilder.setOngoing(true);
    mBuilder.setWhen(System.currentTimeMillis());
    mBuilder.setContentTitle(file_name);
    mBuilder.setContentText("download");
    PendingIntent pendIntent = PendingIntent.getActivity(
            MainActivity.this, NOTIFY_ID, getCurActivityIntent(), PendingIntent.FLAG_UPDATE_CURRENT);
    mBuilder.setContentIntent(pendIntent);
    mNotifyManager.notify(NOTIFY_ID, mBuilder.build());
}