android - BroadcastReceiver CONNECTIVITY_CHANGE 总是在第一次启动应用程序时运行？

Question

我在 Google Developer 上阅读了它:

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

我有这个代码:

公共(public)类 MainActivity 扩展 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;
    }
}

和 //

公共(public)类 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;
}

当我第一次启动应用程序时，此 Intent 总是会触发并显示一个包含当前网络状态的对话框。但是根据这个文件，只有当连接改变时才会发生？如果我只想在网络发生变化时显示此内容，我该怎么办？非常感谢

Answer 1

广播 android.net.conn.CONNECTIVITY_CHANGE 是一个粘性广播。这意味着每当您为此 ACTION 注册一个 BroadcastReceiver 时，它总是会立即被触发，并且 onReceive() 将随着最近的广播连接变化<被调用/强>。这使您无需等待更改即可获得连接的当前状态。

如果你想忽略当前状态，只想处理状态变化，你可以将这个添加到你的onReceive():

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