新的 json 数据未在 android 中显示

Question

从我的服务器检索 json 数据。第一次在我的应用程序中显示数据。但是在更新新数据时，它没有显示。只显示旧数据..当我从应用程序中清除缓存时，它会显示更新的数据。但我想同时显示实时数据。我必须做什么？请帮帮我。

Home.java

public class Home extends Fragment {

    private final String JSON_URL = "https://mywebsite.org/news/api.php";
    private JsonArrayRequest request ;
    private RequestQueue requestQueue ;
    private List<Anime> lstAnime ;
    private RecyclerView recyclerView ;
    ProgressBar loading;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View root = inflater.inflate(R.layout.fragment_home, container, false);

        loading = (ProgressBar)root.findViewById(R.id.bar);
        loading.setMax(100);
        lstAnime = new ArrayList<>() ;
        recyclerView = root.findViewById(R.id.recyclerviewid);

        jsonrequest();

        return root;
    }

    private void jsonrequest() {

        request = new JsonArrayRequest(JSON_URL, new Response.Listener<JSONArray>() {
            @Override
            public void onResponse(JSONArray response) {
                loading.setVisibility(View.GONE);
                JSONObject jsonObject  = null ;

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

                    try {
                        jsonObject = response.getJSONObject(i) ;
                        Anime anime = new Anime() ;
                        anime.setName(jsonObject.getString("title"));
                        anime.setDescription(jsonObject.getString("description"));
                        anime.setDate(jsonObject.getString("date"));
                        anime.setCategorie(jsonObject.getString("category"));
                        anime.setAuthor(jsonObject.getString("admin"));
                        anime.setImage_url(jsonObject.getString("thumbnail"));
                        lstAnime.add(anime);

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
                setuprecyclerview(lstAnime);
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

                if (error instanceof TimeoutError || error instanceof NoConnectionError) {
                    //This indicates that the request has either time out or there is no connection
                    Toast.makeText(getActivity(), "TimeOut...! No Internet",
                            Toast.LENGTH_LONG).show();

                } else if (error instanceof AuthFailureError) {
                    // Error indicating that there was an Authentication Failure while performing the request
                    Toast.makeText(getActivity(), "Failed To Receive Data",
                            Toast.LENGTH_LONG).show();

                } else if (error instanceof ServerError) {
                    //Indicates that the server responded with a error response
                    Toast.makeText(getActivity(), "Our Server Under Maintenance",
                            Toast.LENGTH_LONG).show();
                } else if (error instanceof NetworkError) {
                    //Indicates that there was network error while performing the request
                    Toast.makeText(getActivity(), "Network Not Responding",
                            Toast.LENGTH_LONG).show();
                } else if (error instanceof ParseError) {
                    // Indicates that the server response could not be parsed
                    Toast.makeText(getActivity(), "Please Reload Again!",
                            Toast.LENGTH_LONG).show();
                }
            }
        });

        requestQueue = Volley.newRequestQueue(getActivity());
        requestQueue.add(request);
    }

    private void setuprecyclerview(List<Anime> lstAnime) {

        RecyclerViewAdapter myadapter = new RecyclerViewAdapter(getActivity(),lstAnime);
        recyclerView.setAdapter(myadapter);

        // grid columns is 2
        GridLayoutManager manager = new GridLayoutManager(getActivity(), 2);
        manager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                // 0 is first one and 9 is first one all of others are 2 columns
                if (position == 0 || position == 9) {
                    return 2;
                }
                return 1;}
        });
        recyclerView.setItemAnimator(null);
        recyclerView.setHasFixedSize(true);
        recyclerView.setAdapter(myadapter);
        recyclerView.setLayoutManager(manager);
    }

    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(Uri uri);

    }

}

对不起，我的英语不好。 提前致谢。

Answer 1

我没有看到您初始化 xml 文件中包含的 SwipeRefreshLayout 的地方。您的片段应该实现SwipeRefreshLayout.OnRefreshListener 并覆盖onRefresh() 方法以触发您的网络请求。当使用swipeRefreshLayout.setRefreshing(boolean)完成网络请求时，不要忘记关闭 SwipeRefreshLayout 加载器

您可以查看文档了解更多详情：https://developer.android.com/training/swipe

这是您实现 SwipeRefreshLayout 的片段。

public class Home extends Fragment implements SwipeRefreshLayout.OnRefreshListener{

    private final String JSON_URL = "https://mywebsite.org/news/api.php";
    private JsonArrayRequest request ;
    private RequestQueue requestQueue ;
    private List<Anime> lstAnime ;
    private RecyclerView recyclerView ;
    ProgressBar loading;

    private SwipeRefreshLayout swipeRefreshLayout; //declare SwipeRefreshLayout

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View root = inflater.inflate(R.layout.fragment_home, container, false);

        swipeRefreshLayout = (SwipeRefreshLayout)root.findViewById(R.id.swipeContainer);
        swipeRefreshLayout.setOnRefreshListener(this);  //add refresh listener

        loading = (ProgressBar)root.findViewById(R.id.bar);
        loading.setMax(100);
        lstAnime = new ArrayList<>() ;
        recyclerView = root.findViewById(R.id.recyclerviewid);

        jsonrequest();

        return root;
    }

    private void jsonrequest() {

        request = new JsonArrayRequest(JSON_URL, new Response.Listener<JSONArray>() {
            @Override
            public void onResponse(JSONArray response) {
                swipeRefreshLayout.setRefreshing(false); //Dismiss SwipeRefreshLayout loader
                loading.setVisibility(View.GONE);
                JSONObject jsonObject  = null ;

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

                    try {
                        jsonObject = response.getJSONObject(i) ;
                        Anime anime = new Anime() ;
                        anime.setName(jsonObject.getString("title"));
                        anime.setDescription(jsonObject.getString("description"));
                        anime.setDate(jsonObject.getString("date"));
                        anime.setCategorie(jsonObject.getString("category"));
                        anime.setAuthor(jsonObject.getString("admin"));
                        anime.setImage_url(jsonObject.getString("thumbnail"));
                        lstAnime.add(anime);

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
                setuprecyclerview(lstAnime);
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                swipeRefreshLayout.setRefreshing(false); //Dismiss SwipeRefreshLayout loader

                if (error instanceof TimeoutError || error instanceof NoConnectionError) {
                    //This indicates that the request has either time out or there is no connection
                    Toast.makeText(getActivity(), "TimeOut...! No Internet",
                            Toast.LENGTH_LONG).show();

                } else if (error instanceof AuthFailureError) {
                    // Error indicating that there was an Authentication Failure while performing the request
                    Toast.makeText(getActivity(), "Failed To Receive Data",
                            Toast.LENGTH_LONG).show();

                } else if (error instanceof ServerError) {
                    //Indicates that the server responded with a error response
                    Toast.makeText(getActivity(), "Our Server Under Maintenance",
                            Toast.LENGTH_LONG).show();
                } else if (error instanceof NetworkError) {
                    //Indicates that there was network error while performing the request
                    Toast.makeText(getActivity(), "Network Not Responding",
                            Toast.LENGTH_LONG).show();
                } else if (error instanceof ParseError) {
                    // Indicates that the server response could not be parsed
                    Toast.makeText(getActivity(), "Please Reload Again!",
                            Toast.LENGTH_LONG).show();
                }
            }
        });

        requestQueue = Volley.newRequestQueue(getActivity());
        requestQueue.add(request);
    }

    private void setuprecyclerview(List<Anime> lstAnime) {

        RecyclerViewAdapter myadapter = new RecyclerViewAdapter(getActivity(),lstAnime);
        recyclerView.setAdapter(myadapter);

        // grid columns is 2
        GridLayoutManager manager = new GridLayoutManager(getActivity(), 2);
        manager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                // 0 is first one and 9 is first one all of others are 2 columns
                if (position == 0 || position == 9) {
                    return 2;
                }
                return 1;}
        });
        recyclerView.setItemAnimator(null);
        recyclerView.setHasFixedSize(true);
        recyclerView.setAdapter(myadapter);
        recyclerView.setLayoutManager(manager);
    }

    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(Uri uri);

    }


    @Override
    public void onRefresh() {
        //Whatever is here will be executed when the user swipe to refresh
        jsonrequest(); 
    }
}

Answer 2

如果您想在服务器上的数据更新后立即更新应用程序中的数据，那么您应该使用 Web-Sockets 而不是 API，因为 API 只有在您使用正确的凭据点击它时才会给出响应。