android - 如何使用滑动刷新布局刷新我的 ListView？

Question

import adapter.FeedListAdapter;
import app.AppController;
import data.FeedItem;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.widget.SwipeRefreshLayout;
import android.view.Window;
import android.view.WindowManager;
import android.widget.ListView;
import com.android.volley.Cache;
import com.android.volley.Cache.Entry;
import com.android.volley.Request.Method;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.VolleyLog;
import com.android.volley.toolbox.JsonObjectRequest;

public class MainActivity extends Activity {
    private static final String TAG = MainActivity.class.getSimpleName();
    private ListView listView;
    private FeedListAdapter listAdapter;
    private List<FeedItem> feedItems;
    private String URL_FEED = "http://myozawoo.esy.es/data.php";
    private String URL_FEED2 = "http://api.androidhive.info/feed/feed.json";

    private SwipeRefreshLayout swipeContainer;

//     String page = getIntent().getExtras().getString("page");
    @SuppressLint("NewApi")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, 0);
        setContentView(R.layout.activity_main);

//        String page = getIntent().getExtras().getString("page");

        swipeContainer = (SwipeRefreshLayout) findViewById(R.id.swipeContainer);
        swipeContainer.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {


                listAdapter.notifyDataSetChanged();
            }
        });


        listView = (ListView) findViewById(R.id.list);

        feedItems = new ArrayList<FeedItem>();

        listAdapter = new FeedListAdapter(this, feedItems);
        listView.setAdapter(listAdapter);

        // These two lines not needed,
        // just to get the look of facebook (changing background color & hiding the icon)
//        getActionBar().setBackgroundDrawable(new ColorDrawable(Color.parseColor("#3b5998")));
//        getActionBar().setIcon(
//                new ColorDrawable(getResources().getColor(android.R.color.transparent)));

        // We first check for cached request
//        Cache cache = AppController.getInstance().getRequestQueue().getCache();

        // Page One
        String page = getIntent().getExtras().getString("page");
        if(page.equals("1")) {
            Cache cache = AppController.getInstance().getRequestQueue().getCache();
            Entry entry = cache.get(URL_FEED);
            if (entry != null) {
                // fetch the data from cache
                try {
                    String data = new String(entry.data, "UTF-8");
                    try {
                        parseJsonFeed(new JSONObject(data));
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }

            } else {
                // 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);
            }
        }

        //Page Two

        else if (page.equals("2")) {
            Cache cache = AppController.getInstance().getRequestQueue().getCache();
            Entry entry = cache.get(URL_FEED2);
            if (entry != null) {
                // fetch the data from cache
                try {
                    String data = new String(entry.data, "UTF-8");
                    try {
                        parseJsonFeed(new JSONObject(data));
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }

            } else {
                // making fresh volley request and getting json
                JsonObjectRequest jsonReq = new JsonObjectRequest(Method.GET,
                        URL_FEED2, 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);
            }
        }

        // Other Four Pages
        else {
            Cache cache = AppController.getInstance().getRequestQueue().getCache();
                Entry entry = cache.get(URL_FEED);
                if (entry != null) {
                    // fetch the data from cache
                    try {
                        String data = new String(entry.data, "UTF-8");
                        try {
                            parseJsonFeed(new JSONObject(data));
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    } catch (UnsupportedEncodingException e) {
                        e.printStackTrace();
                    }

                } else {
                    // 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);
                }

        }

        swipeContainer.setColorSchemeColors(android.R.color.holo_blue_bright,
                android.R.color.holo_green_light,
                android.R.color.holo_orange_light,
                android.R.color.holo_red_light);

    }





    /**
     * Parsing json reponse and passing the data to feed view list adapter
     * */
    public void parseJsonFeed(JSONObject response) {
        try {
//            String page = getIntent().getExtras().getString("page");
//            if (page.equals("1"))
            JSONArray feedArray = response.getJSONArray("feed");

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

                final 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();
        }

        swipeContainer.setRefreshing(false);
    }




}

我想做刷新。如果刷新，我可以获得更多数据。我不知道如何获取新数据。谁想帮我？我需要帮助。我使用了滑动刷新布局。我不知道如何连接 parseJSON() {}。抱歉我的英语不好!

Answer 1

将scrollListener 添加到listview 以检查listview item 的位置并启用Swipe Refresh仅当其在顶部时。将以下代码添加到您的 onCreate()

listView.setOnScrollListener(new OnScrollListener() {

@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
}

@Override
public void onScroll(AbsListView view, int firstVisibleItem,
        int visibleItemCount, int totalItemCount) {
    boolean enable = false;
    if(listView != null && listView.getChildCount() > 0){
        // check if the first item of the list is visible
        boolean firstItemVisible = listView.getFirstVisiblePosition() == 0;
        // check if the top of the first item is visible
        boolean topOfFirstItemVisible = listView.getChildAt(0).getTop() == 0;
        // enabling or disabling the refresh layout
        enable = firstItemVisible && topOfFirstItemVisible;
    }
    swipeRefreshLayout.setEnabled(enable);
}});