java - 将 JSON 数据放入列表

Question

我的 JSON 数据正确地来 self 的服务器，我只想将它放入以下数组中，但我不确定 JSON 数据是否正确插入到 ArrayList 中。

这是数组

private List<ShopInfo> createList(int size)  {
    List<ShopInfo> result = new ArrayList<ShopInfo>();
    for (int i = 1; i <= size; i++) {
        ShopInfo ci = new ShopInfo();
        ci.name =    TAG_NAME+i;
        ci.address = TAG_ADDRESS+i;
        result.add(ci);
    }
    return result;
}

我的json

{"success":1,"shops":[{"name":"Test_Shop","address":"1 Big Road Dublin"}

文件

public class OrderCoffee extends Activity {

JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> shopList;
private static String url_all_products = "xxxxxxxxxx/ordercoffee.php";
// products JSONArray
JSONArray shops = null;


// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_SHOPS = "shops";
private static final String TAG_NAME = "name";
private static final String TAG_ADDRESS = "address";


//get a list of participating coffee shops in the locality that are using the app
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.order_coffee);
    new LoadAllProducts().execute();
    RecyclerView recList = (RecyclerView) findViewById(R.id.cardList);
    recList.setHasFixedSize(true);
    LinearLayoutManager llm = new LinearLayoutManager(this);
    llm.setOrientation(LinearLayoutManager.VERTICAL);
    recList.setLayoutManager(llm);
    shopList = new ArrayList<HashMap<String, String>>();
    ShopAdapter ca = new ShopAdapter(createList(3));
    recList.setAdapter(ca);

}


class LoadAllProducts extends AsyncTask<String, String, String> {


    @Override
    protected String doInBackground(String... args) {
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        // getting JSON string from URL
        JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);

        // Check your log cat for JSON reponse
        Log.d("All Products: ", json.toString());

        try {
            // Checking for SUCCESS TAG
            int success = json.getInt(TAG_SUCCESS);

            if (success == 1) {
                // products found
                // Getting Array
                shops = json.getJSONArray(TAG_SHOPS);

                // looping through All Products
                for (int i = 0; i < shops.length(); i++) {
                    JSONObject c = shops.getJSONObject(i);

                    // Storing each json item in variable
                    String id = c.getString(TAG_ADDRESS);
                    String name = c.getString(TAG_NAME);

                    // creating new HashMap
                    HashMap<String, String> map = new HashMap<String, String>();

                    // adding each child node to HashMap key => value
                    map.put(TAG_ADDRESS, id);
                    map.put(TAG_NAME, name);

                    shopList.add(map);


                }
            } else {
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return null;
    }


}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}


private List<ShopInfo> createList(int size)  {
    List<ShopInfo> result = new ArrayList<ShopInfo>();
    for (int i = 1; i <= size; i++) {
        ShopInfo ci = new ShopInfo();
        ci.name =    TAG_NAME+i;
        ci.address = TAG_ADDRESS+i;
        result.add(ci);
    }
    return result;
}
}

商店适配器

  package com.example.strobe.coffeetime;

import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.List;

/**
 * Created by root on 10/04/15.
 */
public class ShopAdapter extends RecyclerView.Adapter<ShopAdapter.ShopViewHolder> {

    private List<ShopInfo> shopList;

    public ShopAdapter(List<ShopInfo> shopList) {
        this.shopList = shopList;
    }


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

    @Override
    public void onBindViewHolder(ShopViewHolder shopViewHolder, int i) {
        ShopInfo ci = shopList.get(i);
        shopViewHolder.vName.setText(ci.name);
        shopViewHolder.vAddress.setText(ci.address);

    }

    @Override
    public ShopViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
        View itemView = LayoutInflater.
                from(viewGroup.getContext()).
                inflate(R.layout.card_layout, viewGroup, false);

        return new ShopViewHolder(itemView);
    }

    public static class ShopViewHolder extends RecyclerView.ViewHolder {

        protected TextView vName;
        protected TextView vAddress;


        public ShopViewHolder(View v) {
            super(v);
            vName =  (TextView) v.findViewById(R.id.name);
            vAddress = (TextView)  v.findViewById(R.id.address);

        }
    }
}

Answer 1

在这行代码中:

ShopAdapter ca = new ShopAdapter(createList(3));

您正在调用 createList(int size) 方法，该方法返回一个包含三个对象的 ArrayList，其中包含虚拟 ShopInfo 对象作为元素。

在 AsyncTask 中，您正在填充 shopList ArrayList，但您实际上从未将 shopList 用于任何事情。

解析 JSON 的更简单方法是使用 Google 的 Gson 库来解析 JSON。

我猜这是您的 ShopInfo 类:

public class ShopInfo {
    String name;
    String address;

    public void setName(String n){
        name = n;
    }

    public void setAddress(String a){
        address = a;
    }

    public String getName(){
        return name;
    }

    public String getAddress(){
        return address;
    }
}

像下面这样创建一个新类:

import java.util.List;
public class ShopInfoList{
     List<ShopInfo> shops;
}

在您的 AsyncTask 的 doInBackground 方法中编写以下代码:

try 
{
    HttpURLConnection connection =  (HttpURLConnection)new URL(YOUR_URL_WITH_JSON).openConnection();
    try 
    {
        InputStream instream =connection.getInputStream();
        BufferedReader breader = new BufferedReader(new InputStreamReader(instream));
        ShopInfoList shopList = new Gson().fromJson(breader, ShopInfoList.class);

        breader.close();
    }
    catch (IOException e) 
    {
        Log.e("Exception parsing JSON", e);
    }
    finally 
    {
        connection.disconnect();
    }
}
catch (Exception e) 
{
    Log.e("Exception parsing JSON", e);
}

但是您仍然需要更新您的 ShopAdapter 以在 List(RecycleView) 中显示它们，您可以在 AsyncTask 的 onPostExecute() 方法中执行此操作。

您可以查看此 URL 以获取有关如何使用 GSON 的更多详细说明 github URL

这里有一些快速指南:

1. 您的Adapter、AsyncTask、Acitvity 类应该分成不同的包，例如:util.asynctasks；和 util.adapters；某个名字.activities; .更易于维护和调试；
2. 保持代码约定。由于您使用 Java 进行编程，因此请使用此指南: https://google-styleguide.googlecode.com/svn/trunk/javaguide.html
3. 当您扩展一个不是您构建的类(如 Activity 或 AsyncTask)时，最好将该类命名为 WhateverExtendingClassName，例如:YourAcitivity。所以您确切地知道它的目的是什么。

好吧，你不想使用 GSON 我个人认为这很可悲 :(。

希望下面的代码对您有用，但要记住一些事项:

1. 我复制了您的代码，更改了一些变量名称并添加了一些代码。
2. 我已对我所做的更改或添加的代码进行了评论。
3. 我在 onPostExecute() AsyncTask 方法中使用了 notifyDataSetChanged() 适配器方法，您应该尝试使用 notifyItemInserted(int)notifyItemRemoved(int) 方法根据您从 API 收到的内容添加和删除项目。

以下是您的 Activity 和 AsyncTask 的代码:

public class OrderCoffee extends Activity {

JSONParser jParser = new JSONParser();
ArrayList<ShopInfo> shopInfoList; //I changed this
private static String url_all_products = "xxxxxxxxxx/ordercoffee.php";
// products JSONArray
JSONArray shops = null;


// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_SHOPS = "shops";
private static final String TAG_NAME = "name";
private static final String TAG_ADDRESS = "address";


//get a list of participating coffee shops in the locality that are using the app
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.order_coffee);
    RecyclerView recList = (RecyclerView) findViewById(R.id.cardList);
    recList.setHasFixedSize(true);
    LinearLayoutManager llm = new LinearLayoutManager(this);
    llm.setOrientation(LinearLayoutManager.VERTICAL);
    recList.setLayoutManager(llm);
    shopInfoList = new ArrayList<ShopInfo>();//I changed this
    ShopAdapter shopAdapter = new ShopAdapter(ShopInfoList);//I changed this
    recList.setAdapter(shopAdapter);//I changed this

    LoadAllProducts loadAllProducts = new LoadAllProducts(shopAdapter)//I added this
    loadAllProducts.execute();//I changed this
}


class LoadAllProducts extends AsyncTask<String, String, String> {

    ShopAdapter shopAdapter;//I added this
    ArrayList<ShopInfo> shopInfoList = new ArrayList<ShopInfo>();//I added this

    public LoadAllProducts(ShopAdapter shopAdapter)//I added this
    {
        this.shopAdapter = shopAdapter;//I added this
    }

    @Override
    protected String doInBackground(String... args) //I changed this{
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        // getting JSON string from URL
        JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);

        // Check your log cat for JSON reponse
        Log.d("All Products: ", json.toString());

        try {
            // Checking for SUCCESS TAG
            int success = json.getInt(TAG_SUCCESS);

            if (success == 1) {
                // products found
                // Getting Array
                shops = json.getJSONArray(TAG_SHOPS);

                // looping through All Products
                for (int i = 0; i < shops.length(); i++) {
                    JSONObject c = shops.getJSONObject(i);

                    // Storing each json item in variable
                    String id = c.getString(TAG_ADDRESS);
                    String name = c.getString(TAG_NAME);
                    ShopInfo shopInfo = new ShopInfo();//I changed this
                    shopInfo.setId(id);//I changed this
                    shopInfo.setName(name);//I changed this

                    shopInfoList.add(shopInfo);//I changed this
                }
            } else {

            }
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return null;
    }

    @Override
   protected void onPostExecute(String result)//I added this{
      shopAdapter.setShopList(shopInfoList); //I added this
      shopAdapter.notifyDataSetChanged();   //I added this
   }
}

以及适配器代码:

public class ShopAdapter extends RecyclerView.Adapter<ShopAdapter.ShopViewHolder> {

    private ArrayList<ShopInfo> shopList;//I added this

    public ShopAdapter(ArrayList<ShopInfo> shopList)//I added this {
        this.shopList = shopList;//I added this
    }

    public void setShopList(ArrayList<ShopInfo> shopList)
    {
         this.shopList = shopList;
    }


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

    @Override
    public void onBindViewHolder(ShopViewHolder shopViewHolder, int i) {
        ShopInfo ci = shopList.get(i);
        shopViewHolder.vName.setText(ci.name);
        shopViewHolder.vAddress.setText(ci.address);

    }

    @Override
    public ShopViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
        View itemView = LayoutInflater.
                from(viewGroup.getContext()).
                inflate(R.layout.card_layout, viewGroup, false);

        return new ShopViewHolder(itemView);
    }

    public static class ShopViewHolder extends RecyclerView.ViewHolder {

        protected TextView vName;
        protected TextView vAddress;


        public ShopViewHolder(View v) {
            super(v);
            vName =  (TextView) v.findViewById(R.id.name);
            vAddress = (TextView)  v.findViewById(R.id.address);

        }
    }
}