java - 网络不可用时无法显示 Toast 通知

Question

我正在尝试通过回调测试网络可用性。

我想在连接不可用时显示 toast 通知。当我可以访问互联网时， onAvailable() 工作正常。

onAvailable() 似乎不起作用。带有消息“无互联网连接”的 Toast 不会显示。

我已经阅读了文档中有关 unAvailable() 的一些信息。提到了超时值。我假设 onUnavailable() 在此超时后被调用。但是，如果它与问题有关，我不知道。

ConnectivityManager.NetworkCallback networkCallback = new ConnectivityManager.NetworkCallback() {
            @Override
            public void onAvailable(@NonNull Network network) {
                Toast.makeText(MainActivity.this, "Request successful", Toast.LENGTH_LONG).show();
            }

            @Override
            public void onUnavailable() {
                super.onUnavailable();
                Toast.makeText(MainActivity.this, "No internet connection", Toast.LENGTH_LONG).show();
        }
        };
        final ConnectivityManager connectivityManager
                = (ConnectivityManager) MainActivity.this.getSystemService(Context.CONNECTIVITY_SERVICE);


        connectivityManager.registerNetworkCallback(new NetworkRequest.Builder()
                .addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
                .build(), networkCallback);

Answer 1

Apps targeting Android 7.0 (API level 24) and higher do not receive CONNECTIVITY_ACTION broadcasts if they declare the broadcast receiver in their manifest. Apps will still receive CONNECTIVITY_ACTION broadcasts if they register their BroadcastReceiver with Context.registerReceiver() and that context is still valid.

这是link寻求解决方案