private ConnectivityManager mConnectivityManager;      private NetworkInfo netInfo; 在onCreate 注册广播 IntentFilter mFilter = new IntentFilter();  mFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION); registerReceiver(myNetReceiver, mFilter);一定要在onDestroy()方法注销广播    @Override    public void onDestroy() {         super.onDestroy();        if(myNetReceiver!=null){                unregisterReceiver(myNetReceiver);         }    }rl_error_item是布局文件类似QQ列表显示的未连接网络状态XML布局    private BroadcastReceiver myNetReceiver = new BroadcastReceiver() {                     @Override          public void onReceive(Context context, Intent intent) {                        String action = intent.getAction();                 if (action.equals(ConnectivityManager.CONNECTIVITY_ACTION)) {                                           mConnectivityManager = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);                     netInfo = mConnectivityManager.getActiveNetworkInfo();                       if(netInfo != null && netInfo.isAvailable()) {                           //网络连接                         String name = netInfo.getTypeName();                          if(netInfo.getType()==ConnectivityManager.TYPE_WIFI || netInfo.getType()==ConnectivityManager.TYPE_ETHERNET || netInfo.getType()==ConnectivityManager.TYPE_MOBILE){                             //3g网络                               rl_error_item.setVisibility(View.GONE);                        }                       } else {                           //网络断开                            rl_error_item.setVisibility(View.VISIBLE);                    }                 }                       }      };