Question

我不知道为什么当我连接或断开wifi时，在wifi接收器的下面发布的代码中相应的回调，被调用至少三次，并且

因此，如果我想根据当前的wifi状态调用一个函数，那么该函数将被多次调用，我不希望这样的行为，特别是在

中

当有wifi连接时应调用的函数，我正在显示一个对话框，并且该调用将被多次调用，对话框将是多次调用会导致重叠。

请在下面发布的logcat中找到，这只是我得到的一个例子。

请让我知道为什么wifi状态的相应回调被多次调用，以及如何避免这种多次调用？

码：

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

    tv_status = (TextView) findViewById(R.id.tv_status);

    this.registerReceiver(this.myWifiReceiver, new IntentFilter(WifiManager.SUPPLICANT_STATE_CHANGED_ACTION));
}

private BroadcastReceiver myWifiReceiver = new BroadcastReceiver() {

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO Auto-generated method stub
        Log.d(TAG, "@onReceive()");

        mConnMgr = (ConnectivityManager)getSystemService(network_service);
        WifiManager wifiMgr = (WifiManager) context.getSystemService(WiFi_Service);

        switch (wifiMgr.getWifiState()) {
        case WifiManager.WIFI_STATE_ENABLED:
            Log.d(TAG, "wifi enabled");

            if (mConnMgr != null) {
                networkInfo = mConnMgr.getActiveNetworkInfo();
                if (networkInfo != null) {
                    switch(networkInfo.getType()) {
                    case ConnectivityManager.TYPE_WIFI: 
                        if (networkInfo.isConnected()) {
                            tv_status.setText("Connected");
                            Log.d(TAG, "Connected");
                        }else if (networkInfo.isConnectedOrConnecting()) {
                            tv_status.setText("Status: CONNECTED Or CONNECTING");
                            Log.d(TAG, "Status: CONNECTED Or CONNECTING");
                        }else if (networkInfo.isFailover()){
                            Log.d(TAG, "Status: FailOver");
                        }else if (networkInfo.isRoaming()) {
                            Log.d(TAG, "Status: Roaming");
                        }else if (networkInfo.isAvailable()) {
                            Log.d(TAG, "Status: Available");
                        } else {
                            Log.d(TAG, "Status: disconnected");
                        }
                        break;

                    }
                }else {
                    tv_status.setText("Status: No Default NetWork Connected");
                    Log.d(TAG, "Status: No Default NetWork Connected");
                }
            } else {
                tv_status.setText("Status:  ConnMgr is null");
                Log.d(TAG, "Status:  ConnMgr is null");
            }

            break;

logcat的：

03-04 15:31:31.031: D/MainActivity(16120): @onReceive()
03-04 15:31:31.031: D/MainActivity(16120): wifi enabled
03-04 15:31:31.032: D/MainActivity(16120): Status: No Default NetWork Connected
03-04 15:31:31.546: D/MainActivity(16120): @onReceive()
03-04 15:31:31.547: D/MainActivity(16120): wifi enabled
03-04 15:31:31.547: D/MainActivity(16120): Status: No Default NetWork Connected
03-04 15:31:31.617: D/MainActivity(16120): @onReceive()
03-04 15:31:31.618: D/MainActivity(16120): wifi enabled
03-04 15:31:31.620: D/MainActivity(16120): Status: No Default NetWork Connected
03-04 15:31:31.636: D/MainActivity(16120): @onReceive()
03-04 15:31:31.636: D/MainActivity(16120): wifi enabled
03-04 15:31:31.637: D/MainActivity(16120): Status: No Default NetWork Connected
03-04 15:32:28.661: D/MainActivity(16120): @onReceive()
03-04 15:32:28.663: D/MainActivity(16120): wifi enabled
03-04 15:32:28.666: D/MainActivity(16120): Status: No Default NetWork Connected
03-04 15:32:28.708: D/MainActivity(16120): @onReceive()
03-04 15:32:28.709: D/MainActivity(16120): wifi enabled
03-04 15:32:28.710: D/MainActivity(16120): Status: No Default NetWork Connected
03-04 15:32:28.722: D/MainActivity(16120): @onReceive()
03-04 15:32:28.722: D/MainActivity(16120): wifi enabled
03-04 15:32:28.722: D/MainActivity(16120): Status: No Default NetWork Connected

Update_1 ：

使用计时器的MySolution ：

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

    tv_status = (TextView) findViewById(R.id.tv_status);
    IntentFilter intfil = new IntentFilter(WifiManager.SUPPLICANT_STATE_CHANGED_ACTION);

    this.registerReceiver(this.myWifiReceiver, intfil);
}

private BroadcastReceiver myWifiReceiver = new BroadcastReceiver() {

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO Auto-generated method stub
        Log.d(TAG, "@onReceive()");
        Timer t1 = new Timer();
        Timer t2 = new Timer();

        if (!locked) {
            if (scheduled1) {
                t1.cancel();
                t1.purge();
            }
            if (scheduled2) {
                t2.cancel();
                t2.purge();
            }

            WifiManager wifiMgr = (WifiManager) context.getSystemService(WiFi_Service);

            switch (wifiMgr.getWifiState()) {
            case WifiManager.WIFI_STATE_ENABLED:
                Log.d(TAG, "wifi enabled");
                locked = true;
                t1 = new Timer();
                t1.schedule(MQTTReceiverLockTimedTask, 4000);
                scheduled1 = true;
                module();
                break;

            case WifiManager.WIFI_STATE_DISABLED:
                Log.d(TAG, "wifi disabled");
                locked = true;
                t2 = new Timer();
                t2.schedule(MQTTReceiverLockTimedTask, 4000);
                scheduled2 = true;
                break;
            }
        }
    }
};

TimerTask MQTTReceiverLockTimedTask = new TimerTask() {

    @Override
    public void run() {
        // TODO Auto-generated method stub
        locked = false;
    }
};

protected void module() {
    // TODO Auto-generated method stub
    mConnMgr = (ConnectivityManager)getSystemService(network_service);

    if (mConnMgr != null) {
        networkInfo = mConnMgr.getActiveNetworkInfo();
        if (networkInfo != null) {
            switch(networkInfo.getType()) {
            case ConnectivityManager.TYPE_WIFI: 
                if (networkInfo.isConnected()) {
                    tv_status.setText("Connected");
                    Log.d(TAG, "Connected");
                }else if (networkInfo.isConnectedOrConnecting()) {
                    tv_status.setText("Status: CONNECTED Or CONNECTING");
                    Log.d(TAG, "Status: CONNECTED Or CONNECTING");
                }else if (networkInfo.isFailover()){
                    Log.d(TAG, "Status: FailOver");
                }else if (networkInfo.isRoaming()) {
                    Log.d(TAG, "Status: Roaming");
                }else if (networkInfo.isAvailable()) {
                    Log.d(TAG, "Status: Available");
                } else {
                    Log.d(TAG, "Status: disconnected");
                }
                break;

            }
        }else {
            tv_status.setText("Status: No Default NetWork Connected");
            Log.d(TAG, "Status: No Default NetWork Connected");
        }
    } else {
        tv_status.setText("Status:  ConnMgr is null");
        Log.d(TAG, "Status:  ConnMgr is null");
    }
}

Answer 1

来自WifiManager documentation WifiManager.SUPPLICANT_STATE_CHANGED_ACTION：

广播意图操作，指示建立与接入点的连接的状态已更改。另外一个提供新的SupplicantState。

您收到许多onReceive()的来电，因为SupplicantState提供了有关建立连接状态的更详细信息。每次这种状态改变时，都会播放新的意图。由于您只需要一个不太详细的信息，因此您似乎多次获得相同的广播。

关于如何避免这种情况：要么搜索另一个倾听意图，例如ConnectivityManager.CONNECTIVITY_ACTION是否符合您的需要，要么尝试Mahmoud Elmorabea的解决方案 - 将当前的WiFi连接状态保存在私有Activity类上的字段，onReceive()上的字段，检查连接状态是否已更改。如果没有，请跳过其余代码。否则，请运行代码并更新您的状态。如果您使用此解决方案，请记住在活动生命周期中保存状态字段。

Answer 2

保持WiFi的当前状态，管理器或其他东西，并且只有在调用onReceive（）时使用与当前状态不同的状态才执行代码。

我们假设您在Activity中使用此代码。

在你的活动中，你将拥有一个名为currentWifiState的属性，起初它等于-100;例如

在您的接收器中，代码就像这样

if (wifiManager.getWifiState() == currentWifiState)
     return;

然后，如果您收到通知的状态与当前状态相同，则不会执行任何操作。

除非Wifi状态发生变化，否则不会执行您的代码。

为什么onReceive（）被多次调用？

2 个答案: