初学 Android,请问下这段监听网络变化的代码在 Android 11 如何变得有效？

我是在教程看到的，但是我在 Android 11 上发现不起作用了,没有报错，但是也没有达到预期的效果

public class MainActivit extends AppCompatActivity { NetReceiver netReceiver; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); netReceiver = new NetReceiver(); IntentFilter intentFilter = new IntentFilter(); intentFilter.addAction("android.net.CONNECTIVITY_CHANGE"); registerReceiver(netReceiver,intentFilter); } @Override protected void onDestroy() { super.onDestroy(); unregisterReceiver(netReceiver); } public class NetReceiver extends BroadcastReceiver{ @Override public void onReceive(Context context, Intent intent) { Toast.makeText(context,"网络发生变化",Toast.LENGTH_LONG).show(); Log.e("mylog","网络发生变化"); } } } 

我尝试在 AndroidManifest.xml 中添加权限,也是没有效果

 <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />