Question

我正在开发一个应用程序，我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，以便从后台服务接收答案并将其保存在数据库中，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，如何刷新活动？我点击它显示数据后点击它正在工作我怎么能动态地做它？

Answer 1

假设您使用的是真正的服务，或者不是AsyncTask。

使用BroadcastReceiver模式。在您的服务中发送广播。

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

在包含列表视图的活动中声明您的接收者

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

注册并取消注册

    @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 2

试试CursorLoader。加载程序监视数据源并在内容更改时带来新结果。

来自official reference

的示例

以下是显示ListView的Fragment的完整实现包含针对联系人内容的查询结果供应商。它使用CursorLoader来管理提供程序上的查询

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 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Button，Imageview等组件如何...都会重新绘制此relativelayout以刷新最新更新。看看@这个 Related ques，How android draws，Invalidate()，requestLayout()

从后台服务收到响应后刷新活动

3 个答案: