android判断网络的状态断开与否

public class ConnectionChangeReceiver extends BroadcastReceiver
{
  @Override
  public void onReceive( Context context, Intent intent )
  {
    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService( Context.CONNECTIVITY_SERVICE );
    NetworkInfo activeNetInfo = connectivityManager.getActiveNetworkInfo();
    NetworkInfo mobNetInfo = connectivityManager.getNetworkInfo(     ConnectivityManager.TYPE_MOBILE );
    if ( activeNetInfo != null )
    {
      Toast.makeText( context, "Active Network Type : " + activeNetInfo.getTypeName(), Toast.LENGTH_SHORT ).show();
    }
    if( mobNetInfo != null )
    {
      Toast.makeText( context, "Mobile Network Type : " + mobNetInfo.getTypeName(), Toast.LENGTH_SHORT ).show();
    }
  }
}
<!-- Needed to check when the network connection changes -->
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

<receiver android:name="com.blackboard.androidtest.receiver.ConnectionChangeReceiver"
          android:label="NetworkConnection">
  <intent-filter>
    <action android:name="android.net.conn.CONNECTIVITY_CHANGE"/>
  </intent-filter>
</receiver>