android - 使用标志 FLAG_UPDATE_CURRENT 时，小部件 onclick 未决 Intent 不会触发

Question

我有一个显示随机数的简单小部件。点击时它会刷新并显示另一个随机数。这是 AppWidgetProvider 的 onUpdate 方法的代码

public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
    super.onUpdate(context, appWidgetManager, appWidgetIds);

    for (int widgetId : appWidgetIds) {
        int number = new Random().nextInt(100);

        RemoteViews remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget_exchange);
        remoteViews.setTextViewText(R.id.widget_textview, String.valueOf(number));

        // Register an onClickListener
        Intent intent = new Intent(context, ExchangeWidgetProvider.class);

        intent.setAction(AppWidgetManager.ACTION_APPWIDGET_UPDATE);
        intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, new int[] {widgetId} );

        PendingIntent pendingIntent = PendingIntent.getBroadcast(context, widgetId, intent, PendingIntent.FLAG_UPDATE_CURRENT);
        remoteViews.setOnClickPendingIntent(R.id.widget_textview, pendingIntent);
        appWidgetManager.updateAppWidget(widgetId, remoteViews);
    }
}

有了这个，小部件会在放置时进行第一次更新，但在单击时不会再次更新。如果我只是将挂起的意向行从:

PendingIntent pendingIntent = PendingIntent.getBroadcast(context, widgetId, intent, PendingIntent.FLAG_UPDATE_CURRENT);

到

PendingIntent pendingIntent = PendingIntent.getBroadcast(context, widgetId, intent, 0);

即唯一改变的是最后一个参数现在是“0”

它现在按预期工作，点击它会显示一个新的随机数。

为什么它可以工作，但当它有 FLAG_UPDATE_CURRENT 标志时却不工作？

Answer 1

注意 PendingIntent 中的文档:

/**
 * Flag indicating that if the described PendingIntent already exists,
 * then keep it but replace its extra data with what is in this new
 * Intent. For use with {@link #getActivity}, {@link #getBroadcast}, and
 * {@link #getService}. <p>This can be used if you are creating intents where only the
 * extras change, and don't care that any entities that received your
 * previous PendingIntent will be able to launch it with your new
 * extras even if they are not explicitly given to it.
 */
public static final int FLAG_UPDATE_CURRENT = 1<<27;

这意味着设置 FLAG_UPDATE_CURRENT 并不意味着更新广播监听器，而是更新挂起的 Intent (如果存在)。在您的情况下，它不存在，因此会被忽略。