如何製作網絡類型偏好？

Question

public class ReplyWithAddressService extends Service{ 

public static final String GOOGLE_GEOCODER = "http://maps.googleapis.com/maps/api/geocode/json?latlng="; 
private String msgRecipient; 
private LocationManager manager; 
private MyLocationListener listener; 
private static double latitude = -1; 
private static double longitude = -1; 
private String provider; 
private String smsMessageString = ""; 
public static String filenames = "AntiTheft"; 
SharedPreferences pref; 
String email; 

@Override 
public IBinder onBind(Intent intent){ 
    return null; 
} 

@Override 
public void onCreate(){ 
    super.onCreate(); 
    Log.d(this.getClass().getName(), "Service created"); 
    pref = getSharedPreferences(filenames, 0); 
    manager = (LocationManager)getSystemService(Context.LOCATION_SERVICE); 
    listener = new MyLocationListener(); 

    if (manager.isProviderEnabled(LocationManager.GPS_PROVIDER)){ 
     provider = LocationManager.GPS_PROVIDER; 
    } 
    else if (manager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)){ 
     provider = LocationManager.NETWORK_PROVIDER; 
    } 

    manager.requestLocationUpdates(provider, 0, 0, listener); 
} 

@Override 
public void onStart(Intent intent, int startId){ 
    super.onStart(intent, startId); 
    Log.d(this.getClass().getName(), "Service started"); 
    //Extract Intent Data 
    msgRecipient = intent.getStringExtra("number"); 
    String emailAddress = pref.getString("keyemail", ""); 
    String contact1 = pref.getString("contact1", ""); 
    String contact2 = pref.getString("contact2", ""); 
    Log.d(this.getClass().getName(), "Number: " + msgRecipient); 
    ConnectivityManager cManager = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE); 
    NetworkInfo info = cManager.getActiveNetworkInfo(); 

    //Get Location 
    if (ReplyWithAddressService.latitude == -1 || ReplyWithAddressService.longitude == -1){ 
     Location location = manager.getLastKnownLocation(provider); 

     if (location != null){ 
      ReplyWithAddressService.latitude = location.getLatitude(); 
      ReplyWithAddressService.longitude = location.getLongitude(); 

      if (info != null){ 

       if (info.isConnected()){ 
        String address = ReplyWithAddressService.getAddressFromGPSData(ReplyWithAddressService.latitude, ReplyWithAddressService.longitude); 
        smsMessageString += "Current Location: " + address + "."; 
       } 
      } 

      smsMessageString += "Link: http://maps.google.com/maps?q=" + ReplyWithAddressService.latitude + "+" + ReplyWithAddressService.longitude; 
      Log.d("Message", smsMessageString); 
     } 
     else{ 
      smsMessageString = "Location Data is Not Available"; 
     } 
    } 

    SmsManager sManager = SmsManager.getDefault(); 
    String number = msgRecipient; 
    String contactNo1 = contact1; 
    String contactNo2 = contact2; 
    email = emailAddress; 

    //Send SMS message 
    sManager.sendTextMessage(number, null, smsMessageString, null, null); 
    sManager.sendTextMessage(contactNo1, null, smsMessageString, null, null); 
    sManager.sendTextMessage(contactNo2, null, smsMessageString, null, null); 

    try{ 
     sendMail(); 
    } catch(MessagingException e){ 
     e.printStackTrace(); 
    } 

    stopSelf(startId); 
} 

我正在開發一個位置跟蹤器移動應用程序，一旦丟失的手機檢索到位置，它會將當前位置發送到預定義的電子郵件地址和手機號碼。如果我的手機連接到Wi-Fi，沒有問題，但是當我關閉Wi-Fi時，我無法通過電子郵件接收位置信息，我只想知道我該如何檢查是否存在在我的手機中連接任何Wi-Fi，如果是，則優先使用Wi-Fi，如果不是，則自動啓用移動網絡以發送電子郵件消息。我的目的是確保電子郵件可以在任何情況下發送出去（不管Wi-Fi是否存在）...希望有人能幫助我，謝謝...

Answer 1

您可以註冊一個BroadcastReceiver來通知當WiFi連接已建立或已被更改時。

註冊的BroadcastReceiver：

IntentFilter intentFilter = new IntentFilter(); 
intentFilter.addAction(WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION); 
registerReceiver(broadcastReceiver, intentFilter); 

然後在該廣播接收器，你可以使用類似：

@Override 
public void onReceive(Context context, Intent intent) { 
    final String action = intent.getAction(); 
    if (action.equals(WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION)) { 
     if (intent.getBooleanExtra(WifiManager.EXTRA_SUPPLICANT_CONNECTED, false)) { 
      //wifi is connected. You can do stuff here. 
     } else { 
      // wifi connection is gone. 
     } 
    } 

文檔的廣播接收器： http://developer.android.com/reference/android/content/BroadcastReceiver.html

Google文檔WifiManager： http://developer.android.com/reference/android/net/wifi/WifiManager.html

在使用上述代碼之前，您需要檢查設備是否已連接到wifi，因爲上述代碼只會在連接狀態發生變化時通知您。它首先被連接起來。要檢查，你可以使用：

WifiManager wifiManager = Context.getSystemService(Context.WIFI_SERVICE); 
    WifiInfo wifiInfo = wifiManager.getConnectionInfo(); 
    if (wifiInfo != null) { 
     //connection is established 
    }