收到后台服务响应后刷新activity

Question

我正在开发一个应用程序，我在其中使用后台服务向服务器发送请求，然后将响应存储在数据库中并动态显示数据，因为从后台服务接收答案并将它们保存在数据库，知道我正在使用

ListView

显示数据库中的数据。每次在数据库中保存新数据时如何刷新 activity？ 我试过在点击后显示数据它正在工作我怎样才能动态地做到这一点？

Answer 1

尝试CursorLoader。 Loader监控数据源，当内容改变时带来新的结果。

示例来自 official reference

Here is the full implementation of a Fragment that displays a ListView containing the results of a query against the contacts content provider. It uses a CursorLoader to manage the query on the provider

public static class CursorLoaderListFragment extends ListFragment
        implements OnQueryTextListener, OnCloseListener,
        LoaderManager.LoaderCallbacks<Cursor> {

    // This is the Adapter being used to display the list's data.
    SimpleCursorAdapter mAdapter;

    // The SearchView for doing filtering.
    SearchView mSearchView;

    // If non-null, this is the current filter the user has provided.
    String mCurFilter;

    @Override public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        // Give some text to display if there is no data.  In a real
        // application this would come from a resource.
        setEmptyText("No phone numbers");

        // We have a menu item to show in action bar.
        setHasOptionsMenu(true);

        // Create an empty adapter we will use to display the loaded data.
        mAdapter = new SimpleCursorAdapter(getActivity(),
                android.R.layout.simple_list_item_2, null,
                new String[] { Contacts.DISPLAY_NAME, Contacts.CONTACT_STATUS },
                new int[] { android.R.id.text1, android.R.id.text2 }, 0);
        setListAdapter(mAdapter);

        // Start out with a progress indicator.
        setListShown(false);

        // Prepare the loader.  Either re-connect with an existing one,
        // or start a new one.
        getLoaderManager().initLoader(0, null, this);
    }

    public static class MySearchView extends SearchView {
        public MySearchView(Context context) {
            super(context);
        }

        // The normal SearchView doesn't clear its search text when
        // collapsed, so we will do this for it.
        @Override
        public void onActionViewCollapsed() {
            setQuery("", false);
            super.onActionViewCollapsed();
        }
    }

    @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        // Place an action bar item for searching.
        MenuItem item = menu.add("Search");
        item.setIcon(android.R.drawable.ic_menu_search);
        item.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM
                | MenuItem.SHOW_AS_ACTION_COLLAPSE_ACTION_VIEW);
        mSearchView = new MySearchView(getActivity());
        mSearchView.setOnQueryTextListener(this);
        mSearchView.setOnCloseListener(this);
        mSearchView.setIconifiedByDefault(true);
        item.setActionView(mSearchView);
    }

    public boolean onQueryTextChange(String newText) {
        // Called when the action bar search text has changed.  Update
        // the search filter, and restart the loader to do a new query
        // with this filter.
        String newFilter = !TextUtils.isEmpty(newText) ? newText : null;
        // Don't do anything if the filter hasn't actually changed.
        // Prevents restarting the loader when restoring state.
        if (mCurFilter == null && newFilter == null) {
            return true;
        }
        if (mCurFilter != null && mCurFilter.equals(newFilter)) {
            return true;
        }
        mCurFilter = newFilter;
        getLoaderManager().restartLoader(0, null, this);
        return true;
    }

    @Override public boolean onQueryTextSubmit(String query) {
        // Don't care about this.
        return true;
    }

    @Override
    public boolean onClose() {
        if (!TextUtils.isEmpty(mSearchView.getQuery())) {
            mSearchView.setQuery(null, true);
        }
        return true;
    }

    @Override public void onListItemClick(ListView l, View v, int position, long id) {
        // Insert desired behavior here.
        Log.i("FragmentComplexList", "Item clicked: " + id);
    }

    // These are the Contacts rows that we will retrieve.
    static final String[] CONTACTS_SUMMARY_PROJECTION = new String[] {
        Contacts._ID,
        Contacts.DISPLAY_NAME,
        Contacts.CONTACT_STATUS,
        Contacts.CONTACT_PRESENCE,
        Contacts.PHOTO_ID,
        Contacts.LOOKUP_KEY,
    };

    public Loader<Cursor> onCreateLoader(int id, Bundle args) {
        // This is called when a new Loader needs to be created.  This
        // sample only has one Loader, so we don't care about the ID.
        // First, pick the base URI to use depending on whether we are
        // currently filtering.
        Uri baseUri;
        if (mCurFilter != null) {
            baseUri = Uri.withAppendedPath(Contacts.CONTENT_FILTER_URI,
                    Uri.encode(mCurFilter));
        } else {
            baseUri = Contacts.CONTENT_URI;
        }

        // Now create and return a CursorLoader that will take care of
        // creating a Cursor for the data being displayed.
        String select = "((" + Contacts.DISPLAY_NAME + " NOTNULL) AND ("
                + Contacts.HAS_PHONE_NUMBER + "=1) AND ("
                + Contacts.DISPLAY_NAME + " != '' ))";
        return new CursorLoader(getActivity(), baseUri,
                CONTACTS_SUMMARY_PROJECTION, select, null,
                Contacts.DISPLAY_NAME + " COLLATE LOCALIZED ASC");
    }

    public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
        // Swap the new cursor in.  (The framework will take care of closing the
        // old cursor once we return.)
        mAdapter.swapCursor(data);

        // The list should now be shown.
        if (isResumed()) {
            setListShown(true);
        } else {
            setListShownNoAnimation(true);
        }
    }

    public void onLoaderReset(Loader<Cursor> loader) {
        // This is called when the last Cursor provided to onLoadFinished()
        // above is about to be closed.  We need to make sure we are no
        // longer using it.
        mAdapter.swapCursor(null);
    }
}

Answer 2

假设您使用的是真正的服务或不是 AsyncTask。

使用 BroadcastReceiver 模式。 在您的服务中发送广播。

LocalBroadcastManager.getInstance(context).sendBroadcast(new Intent("data_changed"));

在包含列表视图的 activity 中声明接收器

  private BroadcastReceiver dataChangeReceiver= new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        // update your listview
    }
};

注册和取消注册

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    IntentFilter inF = new IntentFilter("data_changed");
    LocalBroadcastManager.getInstance(this).registerReceiver(dataChangeReceiver,inF);



}
 @Override
protected void onPause() {
    super.onPause();
    LocalBroadcastManager.getInstance(this).unregisterReceiver(dataChangeReceiver);
}

Answer 3

 You can refresh the data of activity by using Broadcast receiver. To update 
 the view in UI you can go for .invalidate() in the view which you want to refresh. For Example
  RelativeLayout slidingUpLayout=(RelativeLayout) view.findViewById(R.id.slidingLayout);
  slidingUpLayout.invalidate();

现在无论按钮、图像视图等组件...在这个相对布局中都将被重绘以刷新最新更新。看看@这个 Related ques, How android draws, Invalidate(), requestLayout()