我用 DefaultHttpClient 和 HTTPGET 从服务器轮询数据。现在，假设用户在Wi-Fi网络和移动走出了房间。所以手机会自动开始使用3G网络。是否有任何回调对于这样的变化，我应该如何处理这样的变化。我应该重新开始投票还是操作系统照顾适当进行更改

I use DefaultHttpClient and HttpGet to poll data from server. Now, say a user was in Wi-fi network and moves out of the room. So the phone automatically starts using the 3G network. Are there any call-backs for such change, and how should I handle such changes. Should I start polling again or does the OS take care to make the changes appropriately

推荐答案

您可以设置一个接收器在你的清单：

You can set up a Receiver in your manifest:

<receiver
  android:name=".NetworkChangeReceiver"
  android:label="NetworkChangeReceiver">
  <intent-filter>
    <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
    <action android:name="android.net.wifi.WIFI_STATE_CHANGED" />
  </intent-filter>
</receiver>

和实施接收像这样的东西：

public class NetworkChangeReceiver extends BroadcastReceiver {

  @Override
  public void onReceive(final Context context, final Intent intent) {
    final ConnectivityManager connMgr = (ConnectivityManager) 
    context.getSystemService(Context.CONNECTIVITY_SERVICE);

    final android.net.NetworkInfo wifi = 
    connMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI);

    final android.net.NetworkInfo mobile = 
    connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);

    if (wifi.isAvailable()) {
      //Do something
    if (mobile.isAvailable()) {
      //Do something else
    }
  }
}

如果你保持一个持久连接它会往下走，你必须重新建立。

If you are keeping a persistent connection it will go down and you have to re-establish it.

如果您正在计划一个服务，你是不是保持连接的执着，你不会有问题。

If you are scheduling a service and you are not keeping the connection persistent, you will not have problems.