android - 如何在 SyncAdapter 完成 Sync 后刷新 Android ListView

Question

我扩展了一个 AbstractThreadedSyncAdapter 并让它每隔 x 分钟或当我通过代码手动请求同步时自动与我的服务器同步数据。效果很好。

所以现在下一步是自动更新一个包含消息的 ListView 和另一个包含分配的作业的 ListView。

我发现的示例都假定您正在从同一 Activity 中更改数据集，或者您可以访问 ListView 绑定(bind)到的数据库游标。不幸的是，对于 Android 同步适配器，情况并非如此。它在后台运行，据我所知没有任何有用的引用。

我的同步适配器:

public class VttSyncAdapter extends AbstractThreadedSyncAdapter {
    private final AccountManager mAccountManager;

    public VttSyncAdapter(Context context, boolean autoInitialize) {
        super(context, autoInitialize);
        mAccountManager = AccountManager.get(context);
    }

    @Override
    public void onPerformSync(Account account, Bundle extras, String authority, ContentProviderClient provider, SyncResult syncResult) {
        Log.d("Vtt", "onPerformSync for account[" + account.name + "]");
        try 
        {         
            //GET SOME DATA FROM WEBSERVICE AND INSERT INTO SQLITE DB
        } catch (IOException e) {
            e.printStackTrace();
        }

        //WHAT WOULD ONE DO HERE TO ALERT THE LISTVIEW THAT IT SHOULD REFRESH?

        } catch (Exception e) {
            e.printStackTrace();

    }

    public String getsharedresourcestring(String key)
    {
        Context context = getContext();
        SharedPreferences sharedPref = context.getSharedPreferences(context.getString(R.string.preference_file_key), MODE_PRIVATE);
        return sharedPref.getString(key,null);
    }

}

我的日程 fragment 代码:

public class ScheduleFragment extends Fragment {
    private ListView listView;
    private List<DeliveryScheduleEntryModel> schedules;


    public ScheduleFragment() {
        // Required empty public constructor
    }

    public static ScheduleFragment newInstance(String param1, String param2) {
        ScheduleFragment fragment = new ScheduleFragment();
        Bundle args = new Bundle();
        //args.putString(ARG_PARAM1, param1);
        //args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            //mParam1 = getArguments().getString(ARG_PARAM1);
            //mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View ret = inflater.inflate(R.layout.fragment_schedule, container, false);

        listView = (ListView) ret.findViewById(R.id.listViewSchedule);

        //GET OUR DATA
        Activity activity = this.getActivity();
        ContentResolver contentResolver = activity.getContentResolver();
        schedules = getSchedule(contentResolver);

        DeliveryScheduleEntryModelList customList = new DeliveryScheduleEntryModelList(activity, schedules);

        listView.setAdapter(customList);
        return ret;
    }

    public List<DeliveryScheduleEntryModel> getSchedule(ContentResolver cr)
    {
        Context context = getContext();
        VttDataSource db = new VttDataSource(context);
        db.open();
        List<DeliveryScheduleEntryModel> ret = db.getAllDeliveryScheduleEntryModel();
        db.close();

        return ret;
    }
}

Answer 1

//WHAT WOULD ONE DO HERE TO ALERT THE LISTVIEW THAT IT SHOULD REFRESH?

像这样发送本地广播:

Intent intent = new Intent();
intent.setAction("com.your_package.name.REFRESH_LIST");
LocalBroadcastManager.getInstance(this).sendBroadcast(intent);

让 Fragment 和 ListView 声明一个 BroadcastReceiver:

private BroadcastReceiver myReceiver = new BroadcastReceiver()
{
    @Override
    public void onReceive(Context context, Intent intent)
    {

        String sAction = intent.getAction();
        if ("com.your_package.name.REFRESH_LIST".equals(sAction) )
        {
            // update the ListView here
        }
    }
}

注册 BroadcastReceiver 例如在 onAttach() 中:

IntentFilter myFilter = new IntentFilter();
myFilter.addAction("com.your_package.name.REFRESH_LIST");
LocalBroadcastManager.getInstance(this).registerReceiver(myReceiver, myFilter);

并且不要忘记取消注册，例如在 onDetach()

中

LocalBroadcastManager.getInstance(this).unregisterReceiver(myReceiver);

这样，只要 Fragment 附加到 Activity，它就会收到更新消息。

另一种选择是使用某种类型的事件总线(greenrobot、Otto...)。