Android ListView 下拉和上拉

Question

我是 Android 应用程序开发的新手。我想知道如何实现下拉刷新并在Listview 中从服务器上拉获取更多项目。 我该怎么做？ 我的代码从服务器获取项目如下。

private class DownloadJSONItems extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {

        super.onPreExecute();
        // Create a progressbar
        if (!prefs) {

            progressBar.setVisibility(View.VISIBLE);
        }
    }

    @Override
    protected Void doInBackground(Void... params) {

        // Create an array
        arraylist = new ArrayList<HashMap<String, String>>();
        // Retrieve JSON Objects from the given URL address
        jsonobject = JSONfunctions.getJSONfromURL("Server URL",latitude, longitude);
        try {

            // Locate the array name in JSON
            jsonarray = jsonobject.getJSONArray("places");

            for (int i = 0; i < jsonarray.length(); i++) {

                HashMap<String, String> map = new HashMap<String, String>();
                jsonobject = jsonarray.getJSONObject(i);

                double convertString = Double.parseDouble(jsonobject.getString("distance"));
                double convertKMToMile = convertString * 0.6124;
                String convertedValue = String.format("%.2f",convertKMToMile);
                // Retrive JSON Objects
                map.put("places_name", jsonobject.getString("places_name"));
                map.put("distance", convertedValue);
                map.put("places_icon", jsonobject.getString("places_icon"));
                // Set the JSON Objects into the array
                arraylist.add(map);
            }
        } catch (JSONException e) {

            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void args) {

        //Toast.makeText(getActivity(), getString(jsonarray.length()), 6000).show();
        // Pass the results into ListViewAdapter.java
        adapter = new ListViewAdapter(getActivity(), arraylist);
        // Set the adapter to the ListView
        listview.setAdapter(adapter);
        // Close the progressbar
        progressBar.setVisibility(View.GONE);
        if (prefs) {

            prefs = false;
        }
    }
}

谢谢。

Answer 1

https://github.com/Maxwin-z/XListView-Android 有一个不错的库

刷新：

@Override
public void onRefresh() {
    mHandler.postDelayed(new Runnable() {
        @Override
        public void run() {
            start = ++refreshCnt;
            items.clear();
            geneItems();
            // mAdapter.notifyDataSetChanged();
            mAdapter = new ArrayAdapter<String>(XListViewActivity.this, R.layout.list_item, items);
            mListView.setAdapter(mAdapter);
            onLoad();
        }
    }, 2000);
}

加载更多：

@Override
public void onLoadMore() {
    mHandler.postDelayed(new Runnable() {
        @Override
        public void run() {
            geneItems();
            mAdapter.notifyDataSetChanged();
            onLoad();
        }
    }, 2000);
}