Android MySql Volley RecyclerView NetworkImage

Question

我看到了这个教程：https://www.simplifiedcoding.net/android-custom-listview-with-images-using-recyclerview-and-volley/

但是，我遇到了一些问题。这是我的代码：

Config.java

public class Config {
//URL of my API
public static final String DATA_URL = "http://192.168.10.7/connection.php";

//Tags for my JSON
public static final String TAG_IMAGE_URL = "image";
public static final String TAG_NAME = "name";
public static final String TAG_PRICE = "price";

}

connection.php

<?php
$host="localhost";
$username="root"; 
$password="";
$db_name="datatest";
$con=mysql_connect("$host", "$username", "$password")or die("cannot connect"); 
mysql_select_db("$db_name")or die("cannot select DB");
$sql = "select * from news"; 
$result = mysql_query($sql);
$json = array();

if(mysql_num_rows($result)){
while($row=mysql_fetch_assoc($result)){
$json['news'][]=$row;
}
}
mysql_close($con);
echo json_encode($json); 
?>     

MainActivity.java

public class MainActivity extends AppCompatActivity {


private List<TheMain> listTheMain;

//Creating Views
private RecyclerView recyclerView;
private RecyclerView.LayoutManager layoutManager;
private RecyclerView.Adapter adapter;

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

    //Initializing Views
    recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
    recyclerView.setHasFixedSize(true);
    layoutManager = new LinearLayoutManager(this);
    recyclerView.setLayoutManager(layoutManager);

    listTheMain = new ArrayList<>();

    //Calling method to get data
    getData();
}

//This method will get data from the web api
private void getData(){
    //Showing a progress dialog
    final ProgressDialog loading = ProgressDialog.show(this,"Loading Data", "Please wait...",false,false);

    //Creating a json array request
    JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(Config.DATA_URL,
            new Response.Listener<JSONArray>() {
                @Override
                public void onResponse(JSONArray response) {
                    //Dismissing progress dialog
                    loading.dismiss();

                    //calling method to parse json array
                    parseData(response);
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                }
            });

    //Creating request queue
    RequestQueue requestQueue = Volley.newRequestQueue(this);

    //Adding request to the queue
    requestQueue.add(jsonArrayRequest);
}

//This method will parse json data
private void parseData(JSONArray array){
    for(int i = 0; i<array.length(); i++) {
        TheMain themaina = new TheMain();
        JSONObject json = null;
        try {
            json = array.getJSONObject(i);
            themaina.setImageUrl(json.getString(Config.TAG_IMAGE_URL));
            themaina.setName(json.getString(Config.TAG_NAME));
            themaina.setPrice(json.getString(Config.TAG_PRICE));


        } catch (JSONException e) {
            e.printStackTrace();
        }
        listTheMain.add(themaina);
    }

    //Finally initializing our adapter
    adapter = new CardAdapter(listTheMain, this);

    //Adding adapter to recyclerview
    recyclerView.setAdapter(adapter);
}
}

CardAdapter.java

public class CardAdapter extends RecyclerView.Adapter<CardAdapter.ViewHolder> {

private ImageLoader imageLoader;
private Context context;

List<TheMain> themain;

public CardAdapter(List<TheMain>themain, Context context){
    super();

    this.themain = themain;
    this.context = context;
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.news_list, parent, false);
    ViewHolder viewHolder = new ViewHolder(v);
    return viewHolder;
}

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

    TheMain themaina =  themain.get(position);

    imageLoader = CustomVolleyRequest.getInstance(context).getImageLoader();
    imageLoader.get(themaina.getImageUrl(), ImageLoader.getImageListener(holder.imageView, R.mipmap.ic_launcher, android.R.drawable.ic_dialog_alert));

    holder.imageView.setImageUrl(themaina.getImageUrl(), imageLoader);
    holder.textViewName.setText(themaina.getName());
    holder.textViewPrice.setText(themaina.getPrice());
}

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

class ViewHolder extends RecyclerView.ViewHolder{
    public NetworkImageView imageView;
    public TextView textViewName;
public TextView textViewPrice;
    public ViewHolder(View itemView) {
        super(itemView);
        imageView = (NetworkImageView) itemView.findViewById(R.id.newsOne);
        textViewName = (TextView) itemView.findViewById(R.id.title);
        textViewPrice= (TextView) itemView.findViewById(R.id.price);
         }
}
}

CustomVolleyRequest.java

public class CustomVolleyRequest {

private static CustomVolleyRequest customVolleyRequest;
private static Context context;
private RequestQueue requestQueue;
private ImageLoader imageLoader;

private CustomVolleyRequest(Context context) {
    this.context = context;
    this.requestQueue = getRequestQueue();

    imageLoader = new ImageLoader(requestQueue,
            new ImageLoader.ImageCache() {
                private final LruCache<String, Bitmap>
                        cache = new LruCache<String, Bitmap>(20);

                @Override
                public Bitmap getBitmap(String url) {
                    return cache.get(url);
                }

                @Override
                public void putBitmap(String url, Bitmap bitmap) {
                    cache.put(url, bitmap);
                }
            });
}

public static synchronized CustomVolleyRequest getInstance(Context context) {
    if (customVolleyRequest == null) {
        customVolleyRequest = new CustomVolleyRequest(context);
    }
    return customVolleyRequest;
}

public RequestQueue getRequestQueue() {
    if (requestQueue == null) {
        Cache cache = new DiskBasedCache(context.getCacheDir(), 10 * 1024 * 1024);
        Network network = new BasicNetwork(new HurlStack());
        requestQueue = new RequestQueue(cache, network);
        requestQueue.start();
    }
    return requestQueue;
}

public ImageLoader getImageLoader() {
    return imageLoader;
}
}

TheMain.java

public class TheMain {

//Data Variables
private String imageUrl;
private String name;
private String price;

//Getters and Setters 
public String getImageUrl() {
    return imageUrl;
}

public void setImageUrl(String imageUrl) {
    this.imageUrl = imageUrl;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getPrice() {
    return price;
}

public void setPrice(String price) {
    this.price = price;
}

}

我没有得到任何结果。 ProgressDialog刚刚开始。什么都没有。

提前致谢。