Android 判断app是否在前台运行

<!-- 前台还是后台 -->
<uses-permission android:name="android.permission.GET_TASKS" />

 private boolean isForeground(Context context) {
         ActivityManager am = (ActivityManager) context
                 .getSystemService(Context.ACTIVITY_SERVICE);
         ComponentName cn = am.getRunningTasks(1).get(0).topActivity;
         String currentPackageName = cn.getPackageName();
         if (!TextUtils.isEmpty(currentPackageName)
                 && currentPackageName.equals(context.getPackageName())) {
             Log.i("yy", "处于前台");
             return true;
         }
         Log.i("yy", "处于后台");
         return false;
     }