更新的 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。

RecyclerViewAdapter.java

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.MyViewHolder> {
    private Context mContext ;
    private List<Anime> mData ;
    RequestOptions option;

    public RecyclerViewAdapter(Context mContext, List<Anime> mData) {
        this.mContext = mContext;
        this.mData = mData;

        // Request option for Glide
        option = new RequestOptions().centerCrop().placeholder(R.drawable.loading_shape).error(R.drawable.loading_shape);
    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        View view ;
        LayoutInflater inflater = LayoutInflater.from(mContext);
        view = inflater.inflate(R.layout.anime_row_item,parent,false) ;
        final MyViewHolder viewHolder = new MyViewHolder(view) ;
        viewHolder.view_container.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                Intent i = new Intent(mContext, Read.class);
                i.putExtra("news_title",mData.get(viewHolder.getAdapterPosition()).getName());
                i.putExtra("news_description",mData.get(viewHolder.getAdapterPosition()).getDescription());
                i.putExtra("anime_studio",mData.get(viewHolder.getAdapterPosition()).getAuthor());
                i.putExtra("anime_category",mData.get(viewHolder.getAdapterPosition()).getCategorie());
                i.putExtra("anime_img",mData.get(viewHolder.getAdapterPosition()).getImage_url());

                mContext.startActivity(i);

            }
        });

        return viewHolder;
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {

        holder.post_title.setText(mData.get(position).getName());
        holder.date.setText(mData.get(position).getDate());
        holder.author.setText(mData.get(position).getAuthor());
        holder.cat_name.setText(mData.get(position).getCategorie());

        // Load Image from the internet and set it into Imageview using Glide
        Glide.with(mContext).load(mData.get(position).getImage_url()).apply(option).into(holder.thumbnail);

    }

    @Override
    public int getItemCount() {
        return mData.size();
    }

    public static class MyViewHolder extends RecyclerView.ViewHolder {

        TextView post_title ;
        TextView date ;
        TextView author ;
        TextView cat_name;
        ImageView thumbnail;
        LinearLayout view_container;

        public MyViewHolder(View itemView) {
            super(itemView);

            view_container = itemView.findViewById(R.id.container);
            post_title = itemView.findViewById(R.id.post_title);
            cat_name = itemView.findViewById(R.id.cat_name);
            date = itemView.findViewById(R.id.date);
            author = itemView.findViewById(R.id.author);
            thumbnail = itemView.findViewById(R.id.thumbnail);

        }
    }
}

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);

    }

}

fragment_home.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.swiperefreshlayout.widget.SwipeRefreshLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/swipeContainer"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

<androidx.core.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        tools:context=".fragments.Home"
        android:orientation="vertical">

        <!-- TODO: Update blank fragment layout -->

        <ProgressBar
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:id="@+id/bar"/>

            <androidx.recyclerview.widget.RecyclerView
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:id="@+id/recyclerviewid">

            </androidx.recyclerview.widget.RecyclerView>
    </LinearLayout>

</androidx.core.widget.NestedScrollView>
</androidx.swiperefreshlayout.widget.SwipeRefreshLayout>

对不起，我的英语不好。 提前致谢。

Answer 1

在您的 jsonrequest() 方法中使用 notifyDataSetChanged 通知您的回收站视图。使用 requestQueue.getCache().clear() 清除缓存； 检查以下代码：

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;
    RecyclerViewAdapter myadapter;
    **SwipeRefreshLayout swipeRefreshLayout;**
    @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();
        setuprecyclerview(lstAnime);
         **swipeRefreshLayout=view.findViewById(R.id.swipeContainer);
            swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
                @Override
                public void onRefresh()
                {
                    jsonrequest();
                    myAdapter.notifyDataSetChanged();
                    swipeRefreshLayout.setRefreshing(false);
                }
            });**
        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();
                    }
                }
                if(myadapter != null)
                myadapter.notifyDataSetChanged();
            }
        }, 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.getCache().clear();//add this line
        requestQueue.add(request);
    }

    private void setuprecyclerview(List<Anime> lstAnime) {

         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);

    }

}

同样在你的 recyclerviewadapter.java 中添加这一行到 recycler 适配器构造函数：

   public RecyclerViewAdapter(Context mContext, List<Anime> mData) {
    this.mContext = mContext;
    this.mData = mData;
    this.notifyDataSetChanged();
    // Request option for Glide
    option = new RequestOptions().centerCrop().placeholder(R.drawable.loading_shape).error(R.drawable.loading_shape);
}

从 xml 文件中删除嵌套的滚动视图：

  <?xml version="1.0" encoding="utf-8"?>
<androidx.swiperefreshlayout.widget.SwipeRefreshLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 android:id="@+id/swipeContainer"
 android:layout_width="match_parent"
 android:layout_height="match_parent">
    <LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        tools:context=".fragments.Home"
        android:orientation="vertical">

        <!-- TODO: Update blank fragment layout -->

        <ProgressBar
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:id="@+id/bar"/>

        <androidx.recyclerview.widget.RecyclerView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:id="@+id/recview">
        </androidx.recyclerview.widget.RecyclerView>
    </LinearLayout>
</androidx.swiperefreshlayout.widget.SwipeRefreshLayout>