Question

我有这个代码从网站上带来JSON数据并且工作得很好

我想做的是，加载10个项目，当用户滚动到底部时，它会加载另外10个项目......等等，直到项目完成

public class MainActivity extends Activity  {
    private static final String TAG = MainActivity.class.getSimpleName();
    private ListView listView;
    private FeedListAdapter listAdapter;
    private List<FeedItem> feedItems;

    //Feeds URL - Your Website URL where you uploaded the admin panel
    private String URL_FEED = "http://EXAMPLE.COM";


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




        //Getting feeds from the website into listview 
        listView = (ListView) findViewById(R.id.list);
        feedItems = new ArrayList<FeedItem>();
        listAdapter = new FeedListAdapter(this, feedItems);
        listView.setAdapter(listAdapter);



            // making fresh volley request and getting json
            JsonObjectRequest jsonReq = new JsonObjectRequest(Method.GET,
                    URL_FEED, null, new Response.Listener<JSONObject>() {

                        @Override
                        public void onResponse(JSONObject response) {
                            VolleyLog.d(TAG, "Response: " + response.toString());
                            if (response != null) {
                                parseJsonFeed(response);
                            }
                        }
                    }, new Response.ErrorListener() {

                        @Override
                        public void onErrorResponse(VolleyError error) {
                            VolleyLog.d(TAG, "Error: " + error.getMessage());
                        }
                    });

            // Adding request to volley request queue
            AppController.getInstance().addToRequestQueue(jsonReq);


    }

    /**
     * Parsing json reponse and passing the data to feed view list adapter
     * */
    private void parseJsonFeed(JSONObject response) {
        try {
            JSONArray feedArray = response.getJSONArray("feed");

            for (int i = 0; i < feedArray.length(); i++) {
                JSONObject feedObj = (JSONObject) feedArray.get(i);

                FeedItem item = new FeedItem();
                item.setId(feedObj.getInt("id"));
                item.setName(feedObj.getString("name"));

                // Image might be null sometimes
                String image = feedObj.isNull("image") ? null : feedObj
                        .getString("image");
                item.setImge(image);
                item.setStatus(feedObj.getString("status"));
                item.setProfilePic(feedObj.getString("profilePic"));
                item.setTimeStamp(feedObj.getString("timeStamp"));

                // url might be null sometimes
                String feedUrl = feedObj.isNull("url") ? null : feedObj
                        .getString("url");
                item.setUrl(feedUrl);

                feedItems.add(item);
            }

            // notify data changes to list adapater
            listAdapter.notifyDataSetChanged();
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }


    ///Menus functions
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int itemId = item.getItemId();

        switch (itemId) {
        case R.id.action_logout:
            session.logoutUser();
            break;
        case R.id.myProfile:
            Intent intent2 = new Intent(this, ProfileActivity.class);
            startActivity(intent2);
            break;
        case R.id.addPhoto:
            Intent intent1 = new Intent(this, UploadPhoto.class);
            startActivity(intent1);
            break;
        }

        // TODO Auto-generated method stub
        return super.onOptionsItemSelected(item);
    }



}

Answer 1

实施onscrolllistener()

public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
    this.currentFirstVisibleItem = firstVisibleItem;
    this.currentVisibleItemCount = visibleItemCount;
}

public void onScrollStateChanged(AbsListView view, int scrollState) {
    this.currentScrollState = scrollState;
    this.isScrollCompleted();
 }

private void isScrollCompleted() {
    if (this.currentVisibleItemCount > 0 && this.currentScrollState == SCROLL_STATE_IDLE) {
        /*** In this way I detect if there's been a scroll which has completed ***/
        /*** do the work for load more date! ***/
        if(!isLoading){
             isLoading = true;
             GetMoreJsonData();
        }
    }
}

当您实现并将此侦听器添加到listview时，这将检测listview的结尾，因为滚动位置位于列表末尾，只是获取更多数据。在加载数据期间，当滚动位置结束时，您需要一个标志一次加载数据。因此，如果数据正在加载，并且在此期间您向上滚动然后向下滚动，那么它将无法获得更多数据用于复制。

你可以创建一个新方法并移动你制作新的截击请求代码并在其中获取json：

private void GetMoreJsonData()
{
    // making fresh volley request and getting json
    JsonObjectRequest jsonReq = new JsonObjectRequest(Method.GET,
            URL_FEED, null, new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    VolleyLog.d(TAG, "Response: " + response.toString());
                    if (response != null) {
                        parseJsonFeed(response);
                    }
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    VolleyLog.d(TAG, "Error: " + error.getMessage());
                }
            });

    // Adding request to volley request queue
    AppController.getInstance().addToRequestQueue(jsonReq);     
}

发送json请求时不要忘记获得10-10个项目

使用android自动加载更多项目

1 个答案: