如何处理wifi和移动数据之间的网络更改？

Question

ConnectivityManager connectivity_mgr = ((ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE));
NetworkInfo net_info = connectivity_mgr.getActiveNetworkInfo();

if (net_info != null && net_info.isConnectedOrConnecting() && !conn_name.equalsIgnoreCase("")) {
    new_con = net_info.getExtraInfo();
    if (new_con != null && !new_con.equalsIgnoreCase(conn_name))
        network_changed = true;
    conn_name = (new_con == null) ? "" : new_con;
    connectionStatus ="connected";
} else {
    if (net_info != null && conn_name.equalsIgnoreCase("")) {
        conn_name = net_info.getExtraInfo();
        connectionStatus ="connected";
        network_changed = true;
    } else if(!new_con.equals(conn_name)) {
        conn_name = "";
        connectionStatus ="disconnected";
        network_changed = true;
    }
}

所以问题是当用户关闭WiFi按钮时，移动数据仍然连接，但我仍然收到WiFi关闭的通知。它指示我网络断开，即使我的手机仍然连接到移动数据。

但一秒钟后，我收到移动数据连接的通知。但是一旦我收到网络断开，我已经关闭了我的VoIP呼叫。因此，当我收到WiFi关闭的通知时，我如何确定移动数据是否仍然连接。

我尝试了getActiveNetworkInfo()，但当我收到WiFi关闭的通知时，它碰巧为null。

Answer 1

您可以利用ConnectivityManagerAPI:特别是在您的用例中，您对RegisterDefaultNetworkCallback():

    public class TestActivity extends AppCompatActivity {

        private ConnectivityManager manager;
        private final ConnectivityManager.NetworkCallback networkCallback = new ConnectivityManager.NetworkCallback() {
            @Override
            public void onAvailable(Network network) {
                super.onAvailable(network);
                // this ternary operation is not quite true, because non-metered doesn't yet mean, that it's wifi
                // nevertheless, for simplicity let's assume that's true
                Log.i("vvv", "connected to " + (manager.isActiveNetworkMetered() ? "LTE" : "WIFI"));
            }

            @Override
            public void onLost(Network network) {
                super.onLost(network);
                Log.i("vvv", "losing active connection");
            }
        };

        @Override
        protected void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            manager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
            manager.registerDefaultNetworkCallback(networkCallback);
        }

        @Override
        protected void onDestroy() {
            super.onDestroy();
            manager.unregisterNetworkCallback(networkCallback);
        }
    }

我的设备在大约半秒内连接到LTE。

这意味着，你无法事先知道，当WIFI断开时，设备最终是否会连接到LTE。因此，您可以采用以下方法：在处理程序上发布一个操作，在该操作中取消调用。如果连接出现任何时间很快-取消计划以前发布的行动。如果您最终处于runnable代码中，那么连接没有快速建立，这意味着您应该结束调用。

    public class TestActivity extends AppCompatActivity {

        private ConnectivityManager manager;

        private final Handler handler = new Handler();
        private final ConnectivityManager.NetworkCallback networkCallback = new ConnectivityManager.NetworkCallback() {
            @Override
            public void onAvailable(Network network) {
                super.onAvailable(network);
                Log.i("vvv", "connected to " + (manager.isActiveNetworkMetered() ? "LTE" : "WIFI"));

                // we've got a connection, remove callbacks (if we have posted any)
                handler.removeCallbacks(endCall);
            }

            @Override
            public void onLost(Network network) {
                super.onLost(network);
                Log.i("vvv", "losing active connection");

                // Schedule an event to take place in a second
                handler.postDelayed(endCall, 1000);
            }
        };

        private final Runnable endCall = new Runnable() {
            @Override
            public void run() {
                // if execution has reached here - feel free to cancel the call
                // because no connection was established in a second
            }
        };

        @Override
        protected void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            manager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
            manager.registerDefaultNetworkCallback(networkCallback);
        }

        @Override
        protected void onDestroy() {
            super.onDestroy();
            manager.unregisterNetworkCallback(networkCallback);
            handler.removeCallbacks(endCall);
        }
    }