[android] 如何判断程序是否在前台运行

private static boolean isAppOnForeground(String packageName) {
YNoteApplication app = YNoteApplication.getInstance();
ActivityManager activityManager = (ActivityManager) app.getSystemService(app.ACTIVITY_SERVICE);
PowerManager manager = (PowerManager) app.getSystemService(Activity.POWER_SERVICE);
RunningTask Info info = activityManager.getRunningTasks(1).get(0);
ComponentName topComponent = info.topActivity;
if (info.numRunning > 0 && manager.isScreenOn()
&& topComponent != null
&& topComponent.getPackageName().equals(packageName)) {
return true;
}
return false;
}