android - ListFragment 在滚动端加载更多

Question

我有我的 ListFragment 并且想知道当我到达底部时在列表中加载更多内容的最佳方法是什么，我相信我需要实现一个 Scroll Listener 但我对何时何地有一个有点困惑调用已执行，如果有人能提供一些线索，我将不胜感激，我知道我的代码现在也有点乱，因为我只是在测试它，所以对此表示歉意。

代码:测试列表 fragment

package com.fragments;

public class TestListFragment extends ListFragment
        implements
        android.support.v4.app.LoaderManager.LoaderCallbacks<List<TestItemModel>> {

    TestCustomArrayAdapter _adapter;

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

        System.out.println("TestListFragment.onActivityCreated");

        // Initially there is no data
        setEmptyText("Refresh: No Data Here");

        // Create an empty adapter we will use to display the loaded data.
        _adapter = new TestCustomArrayAdapter(getActivity());
        setListAdapter(_adapter);

        // 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);

    }

    @Override
    public void onListItemClick(ListView l, View v, int position, long id) {
        // Insert desired behavior here.
        Log.i("TestListFragment", "Item clicked: " + id);
        TestItemModel ti = this._adapter.getItem(position);
        System.out.println(ti.getId());

    }

    @Override
    public Loader<List<TestItemModel>> onCreateLoader(int arg0, Bundle arg1) {
        System.out.println("TestListFragment.onCreateLoader");
        return new TestListLoaderAsync(getActivity());
    }

    @Override
    public void onLoadFinished(Loader<List<TestItemModel>> arg0,
            List<TestItemModel> data) {
        _adapter.setData(data);
        System.out.println("TestListFragment.onLoadFinished");
        // The list should now be shown.
        if (isResumed()) {
            setListShown(true);
        } else {
            setListShownNoAnimation(true);
        }
    }

    @Override
    public void onLoaderReset(Loader<List<TestItemModel>> arg0) {
        _adapter.setData(null);
    }

}

测试自定义数组适配器

package com.adapters;

public class TestCustomArrayAdapter extends ArrayAdapter<TestItemModel> {
    private final LayoutInflater _inflater;
    public OnItemClickListener _ol;
    public ImageLoader _imageLoader;

    public TestCustomArrayAdapter(Context context) {
        super(context, R.layout.test_list_fragment);
        _inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        // Load up Image Loader
        _imageLoader = new ImageLoader(context);

    }

    public void setData(List<TestItemModel> data) {
        clear();
        if (data != null) {
            for (TestItemModel appEntry : data) {
                add(appEntry);
            }
        }
    }

    /**
     * Populate new items in the list.
     */
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // create viewHolder
        View view;

        // Check Views
        if (convertView == null) {
            view = _inflater.inflate(R.layout.test_single_item, parent, false);
        } else {
            view = convertView;
        }

        // Create Items
        TestItemModel item = getItem(position);

        TextView itemLabel = (TextView) view.findViewById(R.id.item_label);
        TextView itemId = (TextView) view.findViewById(R.id.item_id);

        // Create ImageViews
        ImageView image = (ImageView) view.findViewById(R.id.image_id);

        // Create Buttons
        Button btn1 = (Button) view.findViewById(R.id.button_id_1);
        Button btn2 = (Button) view.findViewById(R.id.button_id_2);
        Button btn3 = (Button) view.findViewById(R.id.button_id_3);

        // Create Resources
        Resources resources = this.getContext().getResources();

        // Create Listeners
        _ol = new OnItemClickListener(position, item);

        // Setup TextViews
        itemLabel.setText(item.getName());
        itemId.setText(item.getName());

        // Setup Images
        _imageLoader.DisplayImage(item.getBm(), image);

        // Setup Buttons
        btn1.setOnClickListener(_ol);
        btn1.setTag(1);
        btn2.setOnClickListener(_ol);
        btn2.setTag(2);
        btn3.setOnClickListener(_ol);
        btn3.setTag(3);

        return view;
    }

    private class OnItemClickListener implements OnClickListener {
        private int _position;
        private TestItemModel _testItem;

        public OnItemClickListener(int position, TestItemModel ti) {
            _position = position;
            _testItem = ti;
        }

        // TODO
        // provide functionality for which button was clicked then pass the item
        // to which it was clicked in.
        @Override
        public void onClick(View v) {
            switch (v.getId()) {
            case R.id.button_id_1:
                // btn1 clicked
                Toast.makeText(getContext(),
                        " Button1 clicked at positon" + v.getTag(),
                        Toast.LENGTH_SHORT).show();
                break;
            case R.id.button_id_2:
                // btn2 clicked
                Toast.makeText(getContext(),
                        " Button2 clicked at positon" + v.getTag(),
                        Toast.LENGTH_SHORT).show();
                break;
            case R.id.button_id_3:
                Toast.makeText(getContext(),
                        " Button3 clicked at positon" + v.getTag(),
                        Toast.LENGTH_SHORT).show();
                // btn 3 clciked
                break;
            }

            // the view is the button, so you get get the tag it has set with
            // v.getTag() to know what button is pressed.
            Log.v("YOOO",
                    "Button Click at position " + _position + " " + v.getTag()
                            + " Item ID = " + _testItem.getId());

        }
    }

}

TestListLoaderAsync

打包 com.tasks;

公共(public)类 TestListLoaderAsync 扩展 AsyncTaskLoader> {

private List<TestItemModel> _models;

// Test URLS
private final String[] URLS = {
        "http://www.pressurewasherparts.com.au/upimages/image/Water_Broom/Water%20Broom%203%20Noz%20upright.jpg",
        "http://www.pressurewasherparts.com.au/upimages/image/Water_Broom/Water%20Broom%203%20Noz%20upright.jpg",
        "http://lh3.ggpht.com/_GEnSvSHk4iE/TDSfmyCfn0I/AAAAAAAAF8Y/cqmhEoxbwys/s144-c/_MG_3675.jpg",
        "http://lh6.ggpht.com/_Nsxc889y6hY/TBp7jfx-cgI/AAAAAAAAHAg/Rr7jX44r2Gc/s144-c/IMGP9775a.jpg",
        "http://lh3.ggpht.com/_lLj6go_T1CQ/TCD8PW09KBI/AAAAAAAAQdc/AqmOJ7eg5ig/s144-c/Juvenile%20Gannet%20despute.jpg",
        "http://lh6.ggpht.com/_ZN5zQnkI67I/TCFFZaJHDnI/AAAAAAAABVk/YoUbDQHJRdo/s144-c/P9250508.JPG",
        "http://lh4.ggpht.com/_XjNwVI0kmW8/TCOwNtzGheI/AAAAAAAAC84/SxFJhG7Scgo/s144-c/0014.jpg",
        "http://lh6.ggpht.com/_lnDTHoDrJ_Y/TBvKsJ9qHtI/AAAAAAAAG6g/Zll2zGvrm9c/s144-c/000007.JPG",
        "http://lh6.ggpht.com/_qvCl2efjxy0/TCIVI-TkuGI/AAAAAAAAOUY/vbk9MURsv48/s144-c/DSC_0844.JPG",
        "http://lh4.ggpht.com/_TPlturzdSE8/TBv4ugH60PI/AAAAAAAAMsI/p2pqG85Ghhs/s144-c/_MG_3963.jpg",
        "http://lh4.ggpht.com/_4f1e_yo-zMQ/TCe5h9yN-TI/AAAAAAAAXqs/8X2fIjtKjmw/s144-c/IMG_1786.JPG",
        "http://lh6.ggpht.com/_iFt5VZDjxkY/TB9rQyWnJ4I/AAAAAAAADpU/lP2iStizJz0/s144-c/DSCF1014.JPG",
        "http://lh5.ggpht.com/_hepKlJWopDg/TB-_WXikaYI/AAAAAAAAElI/715k4NvBM4w/s144-c/IMG_0075.JPG",
        "http://lh6.ggpht.com/_OfRSx6nn68g/TCzsQic_z3I/AAAAAAABOOI/5G4Kwzb2qhk/s144-c/EASTER%20ISLAND_Hanga%20Roa_31.5.08_46.JPG",
        "http://lh6.ggpht.com/_ZGv_0FWPbTE/TB-_GLhqYBI/AAAAAAABVxs/cVEvQzt0ke4/s144-c/IMG_1288_hf.jpg",
        "http://lh6.ggpht.com/_a29lGRJwo0E/TBqOK_tUKmI/AAAAAAAAVbw/UloKpjsKP3c/s144-c/31012332.jpg",
        "http://lh3.ggpht.com/_55Lla4_ARA4/TB6xbyxxJ9I/AAAAAAABTWo/GKe24SwECns/s144-c/Bluebird%20049.JPG",
        "http://lh3.ggpht.com/_iVnqmIBYi4Y/TCaOH6rRl1I/AAAAAAAA1qg/qeMerYQ6DYo/s144-c/Kwiat_100626_0016.jpg",
        "http://lh6.ggpht.com/_QFsB_q7HFlo/TCItd_2oBkI/AAAAAAAAFsk/4lgJWweJ5N8/s144-c/3705226938_d6d66d6068_o.jpg",
        "http://lh5.ggpht.com/_JTI0xxNrKFA/TBsKQ9uOGNI/AAAAAAAChQg/z8Exh32VVTA/s144-c/CRW_0015-composite.jpg",
        "http://lh6.ggpht.com/_loGyjar4MMI/S-InVNkTR_I/AAAAAAAADJY/Fb5ifFNGD70/s144-c/Moving%20Rock.jpg",
        "http://lh4.ggpht.com/_L7i4Tra_XRY/TBtxjScXLqI/AAAAAAAAE5o/ue15HuP8eWw/s144-c/opera%20house%20II.jpg",
        "http://lh3.ggpht.com/_rfAz5DWHZYs/S9cstBTv1iI/AAAAAAAAeYA/EyZPUeLMQ98/s144-c/DSC_6425.jpg",
        "http://lh6.ggpht.com/_iGI-XCxGLew/S-iYQWBEG-I/AAAAAAAACB8/JuFti4elptE/s144-c/norvig-polar-bear.jpg",
        "http://lh3.ggpht.com/_M3slUPpIgmk/SlbnavqG1cI/AAAAAAAACvo/z6-CnXGma7E/s144-c/mf_003.jpg",
        "http://lh4.ggpht.com/_loGyjar4MMI/S-InQvd_3hI/AAAAAAAADIw/dHvCFWfyHxQ/s144-c/Rainbokeh.jpg",
        "http://lh4.ggpht.com/_yy6KdedPYp4/SB5rpK3Zv0I/AAAAAAAAOM8/mokl_yo2c9E/s144-c/Point%20Reyes%20road%20.jpg",
        "http://lh5.ggpht.com/_6_dLVKawGJA/SMwq86HlAqI/AAAAAAAAG5U/q1gDNkmE5hI/s144-c/mobius-glow.jpg",
        "http://lh3.ggpht.com/_QFsB_q7HFlo/TCItc19Jw3I/AAAAAAAAFs4/nPfiz5VGENk/s144-c/4551649039_852be0a952_o.jpg",
        "http://lh6.ggpht.com/_TQY-Nm7P7Jc/TBpjA0ks2MI/AAAAAAAABcI/J6ViH98_poM/s144-c/IMG_6517.jpg",
        "http://lh3.ggpht.com/_rfAz5DWHZYs/S9cLAeKuueI/AAAAAAAAeYU/E19G8DOlJRo/s144-c/DSC_4397_8_9_tonemapped2.jpg",
        "http://lh4.ggpht.com/_TQY-Nm7P7Jc/TBpi6rKfFII/AAAAAAAABbg/79FOc0Dbq0c/s144-c/david_lee_sakura.jpg",
        "http://lh3.ggpht.com/_TQY-Nm7P7Jc/TBpi8EJ4eDI/AAAAAAAABb0/AZ8Cw1GCaIs/s144-c/Hokkaido%20Swans.jpg",
        "http://lh3.ggpht.com/_1aZMSFkxSJI/TCIjB6od89I/AAAAAAAACHM/CLWrkH0ziII/s144-c/079.jpg",
        "http://lh5.ggpht.com/_loGyjar4MMI/S-InWuHkR9I/AAAAAAAADJE/wD-XdmF7yUQ/s144-c/Colorado%20River%20Sunset.jpg",
        "http://lh3.ggpht.com/_0YSlK3HfZDQ/TCExCG1Zc3I/AAAAAAAAX1w/9oCH47V6uIQ/s144-c/3138923889_a7fa89cf94_o.jpg",
        "http://lh6.ggpht.com/_K29ox9DWiaM/TAXe4Fi0xTI/AAAAAAAAVIY/zZA2Qqt2HG0/s144-c/IMG_7100.JPG",
        "http://lh6.ggpht.com/_0YSlK3HfZDQ/TCEx16nJqpI/AAAAAAAAX1c/R5Vkzb8l7yo/s144-c/4235400281_34d87a1e0a_o.jpg",
        "http://lh4.ggpht.com/_8zSk3OGcpP4/TBsOVXXnkTI/AAAAAAAAAEo/0AwEmuqvboo/s144-c/yosemite_forrest.jpg",
        "http://lh4.ggpht.com/_6_dLVKawGJA/SLZToqXXVrI/AAAAAAAAG5k/7fPSz_ldN9w/s144-c/coastal-1.jpg",
        "http://lh4.ggpht.com/_WW8gsdKXVXI/TBpVr9i6BxI/AAAAAAABhNg/KC8aAJ0wVyk/s144-c/IMG_6233_1_2-2.jpg",
        "http://lh3.ggpht.com/_loGyjar4MMI/S-InS0tJJSI/AAAAAAAADHU/E8GQJ_qII58/s144-c/Windmills.jpg",
        "http://lh4.ggpht.com/_loGyjar4MMI/S-InbXaME3I/AAAAAAAADHo/4gNYkbxemFM/s144-c/Frantic.jpg",
        "http://lh5.ggpht.com/_loGyjar4MMI/S-InKAviXzI/AAAAAAAADHA/NkyP5Gge8eQ/s144-c/Rice%20Fields.jpg",
        "http://lh3.ggpht.com/_loGyjar4MMI/S-InZA8YsZI/AAAAAAAADH8/csssVxalPcc/s144-c/Seahorse.jpg",
        "http://lh3.ggpht.com/_syQa1hJRWGY/TBwkCHcq6aI/AAAAAAABBEg/R5KU1WWq59E/s144-c/Antelope.JPG",
        "http://lh5.ggpht.com/_MoEPoevCLZc/S9fHzNgdKDI/AAAAAAAADwE/UAno6j5StAs/s144-c/c84_7083.jpg",
        "http://lh4.ggpht.com/_DJGvVWd7IEc/TBpRsGjdAyI/AAAAAAAAFNw/rdvyRDgUD8A/s144-c/Free.jpg",
        "http://lh6.ggpht.com/_iO97DXC99NY/TBwq3_kmp9I/AAAAAAABcz0/apq1ffo_MZo/s144-c/IMG_0682_cp.jpg",
        "http://lh4.ggpht.com/_7V85eCJY_fg/TBpXudG4_PI/AAAAAAAAPEE/8cHJ7G84TkM/s144-c/20100530_120257_0273-Edit-2.jpg" };

public TestListLoaderAsync(Context context) {
    super(context);
}

@Override
public List<TestItemModel> loadInBackground() {

    System.out.println("TestListLoader.loadInBackground");

    // You should perform the heavy task of getting data from
    // Internet or database or other source
    // Here, we are generating some Sample data

    // Create corresponding array of entries and load with data.
    List<TestItemModel> entries = new ArrayList<TestItemModel>(5);
    entries.add(new TestItemModel("Java", "1", URLS[1]));
    entries.add(new TestItemModel("C++", "2", URLS[2]));
    entries.add(new TestItemModel("Python", "3", URLS[3]));
    entries.add(new TestItemModel("JavaScript", "4", URLS[4]));
    entries.add(new TestItemModel("D", "5", URLS[5]));
    entries.add(new TestItemModel("C", "6", URLS[6]));
    entries.add(new TestItemModel("Perl", "7", URLS[7]));
    entries.add(new TestItemModel("Fortran", "8", URLS[8]));
    entries.add(new TestItemModel("Cobalt", "9", URLS[9]));
    entries.add(new TestItemModel("Ruby", "10", URLS[10]));
    entries.add(new TestItemModel("Pascal", "11", URLS[11]));
    entries.add(new TestItemModel("HTML", "12", URLS[12]));
    entries.add(new TestItemModel("CSS", "13", URLS[13]));
    entries.add(new TestItemModel("PHP", "14", URLS[14]));
    entries.add(new TestItemModel("MYSQL", "15", URLS[15]));
    entries.add(new TestItemModel("Fortran", "8", URLS[16]));
    entries.add(new TestItemModel("Cobalt", "9", URLS[17]));
    entries.add(new TestItemModel("Ruby", "10", URLS[18]));
    entries.add(new TestItemModel("Pascal", "11", URLS[19]));
    entries.add(new TestItemModel("HTML", "12", URLS[20]));
    entries.add(new TestItemModel("CSS", "13", URLS[21]));
    entries.add(new TestItemModel("PHP", "14", URLS[22]));
    entries.add(new TestItemModel("MYSQL", "15", URLS[23]));

    TestItemModel lastItem = new TestItemModel("C#", "16", URLS[0]);

    lastItem.setId("TestingId");
    entries.add(lastItem);

    return entries;
}

/**
 * Called when there is new data to deliver to the client. The super class
 * will take care of delivering it; the implementation here just adds a
 * little more logic.
 */
@Override
public void deliverResult(List<TestItemModel> listOfData) {
    if (isReset()) {
        // An async query came in while the loader is stopped. We
        // don't need the result.
        if (listOfData != null) {
            onReleaseResources(listOfData);
        }
    }
    List<TestItemModel> oldApps = listOfData;
    _models = listOfData;

    if (isStarted()) {
        // If the Loader is currently started, we can immediately
        // deliver its results.
        super.deliverResult(listOfData);
    }

    // At this point we can release the resources associated with
    // 'oldApps' if needed; now that the new result is delivered we
    // know that it is no longer in use.
    if (oldApps != null) {
        onReleaseResources(oldApps);
    }
}

/**
 * Handles a request to start the Loader.
 */
@Override
protected void onStartLoading() {
    if (_models != null) {
        // If we currently have a result available, deliver it
        // immediately.
        deliverResult(_models);
    }

    if (takeContentChanged() || _models == null) {
        // If the data has changed since the last time it was loaded
        // or is not currently available, start a load.
        forceLoad();
    }
}

/**
 * Handles a request to stop the Loader.
 */
@Override
protected void onStopLoading() {
    // Attempt to cancel the current load task if possible.
    cancelLoad();
}

/**
 * Handles a request to cancel a load.
 */
@Override
public void onCanceled(List<TestItemModel> apps) {
    super.onCanceled(apps);

    // At this point we can release the resources associated with 'apps'
    // if needed.
    onReleaseResources(apps);
}

/**
 * Handles a request to completely reset the Loader.
 */
@Override
protected void onReset() {
    super.onReset();

    // Ensure the loader is stopped
    onStopLoading();

    // At this point we can release the resources associated with 'apps'
    // if needed.
    if (_models != null) {
        onReleaseResources(_models);
        _models = null;
    }
}

/**
 * Helper function to take care of releasing resources associated with an
 * actively loaded data set.
 */
protected void onReleaseResources(List<TestItemModel> apps) {
}

Answer 1

当你的适配器中getView中的位置到达最后一个位置时，你可以触发“加载更多”事件!