Android应用中怎么对网络连接状态进行监听

 public class NetUtil {      private static final int NETWORK_NONE = -1;      private static final int NETWORK_MOBILE = 0;      private static final int NETWORK_WIFI = 1;   public static int getNetWorkState(Context context) {     // 得到连接管理器对象     ConnectivityManager connectivityManager = (ConnectivityManager) context         .getSystemService(Context.CONNECTIVITY_SERVICE);     NetworkInfo activeNetworkInfo = connectivityManager         .getActiveNetworkInfo();     if (activeNetworkInfo != null && activeNetworkInfo.isConnected()) {       if (activeNetworkInfo.getType() == (ConnectivityManager.TYPE_WIFI)) {         return NETWORK_WIFI;       } else if (activeNetworkInfo.getType() == (ConnectivityManager.TYPE_MOBILE)) {         return NETWORK_MOBILE;       }     } else {       return NETWORK_NONE;     }     return NETWORK_NONE;   } }  public class NetBroadcastReceiver extends BroadcastReceiver {   public NetEvevt evevt = BaseActivity.evevt;   @Override   public void onReceive(Context context, Intent intent) {     // TODO Auto-generated method stub     // 如果相等的话就说明网络状态发生了变化     if (intent.getAction().equals(ConnectivityManager.CONNECTIVITY_ACTION)) {       int netWorkState = NetUtil.getNetWorkState(context);       // 接口回调传过去状态的类型       evevt.onNetChange(netWorkState);     }   }   // 自定义接口   public interface NetEvevt {     public void onNetChange(int netMobile);   } }