用于检查 Internet 连接的广播接收器

Question

我是 android 的初学者。我只想知道什么是广播接收器（如果可能的话，用一个例子），它在 onReceive() 方法上。以及我们如何使用该接收器检查互联网连接。

所以我应该使用相同的方法来检查互联网连接还是只在 Main class 中创建一个静态方法并在其他 classes 中访问它？

Answer 1

好吧，我不是最好的程序员，但这应该有用。

这是针对片段的，但您应该可以轻松地将其更改为 activity.

先做3个变量：

Context _mContext;
BroadcastReceiver br = null;
IntentFilter filter;

在你的 onCreate() 中粘贴：

BroadcastReceiver br = new MyBroadCastReceiver();
IntentFilter filter = new IntentFilter();
filter.addAction(WifiManager.WIFI_STATE_CHANGED_ACTION);
_mContext = getActivity().getApplicationContext()
_mContext.registerReceiver(br, filter);

这样你就可以将片段注册到广播接收器 class MyBroadCastReceiver。

现在制作一个 MyBroadCastReceiver class 并粘贴：

public class MyBroadCastReceiver extends BroadcastReceiver {
            @Override
            public void onReceive(Context context, Intent intent) {
                int extraWifiState = intent.getIntExtra(WifiManager.EXTRA_WIFI_STATE,
                        WifiManager.WIFI_STATE_UNKNOWN);

    switch(extraWifiState) {
        case: WifiManager.WIFI_STATE_DISABLED:
        //do something
        break;
        case WifiManager.WIFI_STATE_ENABLED:
        //do something 
        break;
        case: WifiManager.WIFI_STATE_ENABLING:
        //do something
        break;
        case: WifiManager.WIFI_STATE_DISABLING:
        //do something
        break;
        case: WifiManager.WIFI_STATE_UNKNOWN:
        //do something with data if you desire so, I found it unreliable until now so i've done nothing with it
        }
      }
    }`

返回您的片段并将其粘贴到底部的某处：

    @Override
    public void onPause()    {
        try {
            if (br == null) {
                Log.d("Receiver", "Can't unregister a receiver which was never registered");
            } else {
                getActivity().getApplicationContext().unregisterReceiver(br);
                br = null;
            }
        } catch(Exception err)  {
            Log.e(err.getClass().getName(), err.getMessage(), err);
            Log.e("Receiver not registered", "Couldn't get context");
        }
        super.onPause();
    }

    @Override
    public void onResume()  {
        if(br != null)  {
            Log.d("Receiver", "Can't register receiver which already has been registered");
        }   else    {
            try {
                br = new MyBroadCastReceiver();
                filter = new IntentFilter();
                filter.addAction(WifiManager.WIFI_STATE_CHANGED_ACTION);
                filter.addAction(CONNECTIVITY_SERVICE);
                _mContext = getActivity().getApplicationContext();
                _mContext.registerReceiver(br, filter);
            } catch(Exception err)   {
                Log.e(err.getClass().getName(), err.getMessage(), err);
            }
        }
        super.onResume();
    }

您应该可以在任何地方像这样调用 register/unregister 广播。我希望这足够了

Answer 2

    <receiver
        android:name=".InternetConnectorBroadcastReceiver"
        android:enabled="true">
        <intent-filter>

            <!-- Intent filters for broadcast receiver -->
            <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
            <action android:name="android.net.wifi.WIFI_STATE_CHANGED" />
            <action android:name="android.net.wifi.STATE_CHANGE" />
        </intent-filter>
    </receiver>


       <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
         <uses-permission android:name="android.permission.INTERNET" />

public class InternetConnectionBroadcastReceiver extends BroadcastReceiver {
        public InternetConnectorBroadcastReceiver() {
        }

        @Override
        public void onReceive(Context context, Intent intent) {
        }

}

用于检查 Internet 连接的广播接收器

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