BroadcastReceiver CONNECTIVITY_CHANGE总是在第一次启动应用程序中运行？

Question

I read it on Google Developer:

("android.net.conn.CONNECTIVITY_CHANGE") action whenever the connectivity details have changed

I have this code:

public class MainActivity extends AppCompatActivity {

private NetworkChangeReceiver receiver;
private boolean connIntentFilterIsRegistered;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    receiver = new NetworkChangeReceiver();
}

@Override
protected void onPause() {
    super.onPause();
    if (connIntentFilterIsRegistered) {
        unregisterReceiver(receiver);
        connIntentFilterIsRegistered = false;
    }
}

@Override
protected void onResume() {
    super.onResume();
    if (!connIntentFilterIsRegistered) {
        registerReceiver(receiver, new IntentFilter("android.net.conn.CONNECTIVITY_CHANGE"));
        connIntentFilterIsRegistered = true;
    }
}

and //

public class NetworkUtil {

public static int TYPE_WIFI = 1;
public static int TYPE_MOBILE = 0;
public static int TYPE_NOT_CONNECTED = 2;

public static int getConnectivityStatus(Context context) {
    ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
    if (activeNetwork != null && activeNetwork.isConnectedOrConnecting()) {
        if (activeNetwork.getType() == ConnectivityManager.TYPE_WIFI) {
            return TYPE_WIFI;
        }
        if (activeNetwork.getType() == ConnectivityManager.TYPE_MOBILE) {
            return TYPE_MOBILE;
        }
    }
    return TYPE_NOT_CONNECTED;
}

public static String getConnectivityStatusString(Context context) {
    int conn = NetworkUtil.getConnectivityStatus(context);
    String status = null;
    if (conn == TYPE_MOBILE) {
        status = "Mobile cellular enabled";
    } else if (conn == TYPE_WIFI) {
        status = "Wifi enabled";
    } else if (conn == TYPE_NOT_CONNECTED) {
        status = "Not connected to internet";
    }
    return status;
}

}

when first time i launch app, this intent always fired and displayed a dialog with the current state of network. But based on this document, it only happens when connect change? If I want this display only when network changes, how could i do? Many thanks

Answer 1

The broadcast android.net.conn.CONNECTIVITY_CHANGE is a sticky broadcast . This means that whenever you register a BroadcastReceiver for this ACTION, it will always be triggered immediately and onReceive() will be called with the most recent broadcast connectivity change . This allows you to get the current state of the connectivity without waiting for something to change.

If you want to ignore the current state, and only want to process state changes, you can add this to your onReceive() :

if (isInitialStickyBroadcast()) {
    // Ignore this call to onReceive, as this is the sticky broadcast
} else {
    // Connectivity state has changed
    ... (your code here)
}