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);

                    }

                } 

           }

    };