获取正在显示的Activity-转载

   1. ActivityManager am = (ActivityManager) getSystemService(ACTIVITY_SERVICE); 
   2. ComponentName cn = am.getRunningTasks(1).get(0).topActivity; 
   3. Log.d("", "pkg:"+cn.getPackageName()); 
   4. Log.d("", "cls:"+cn.getClassName());