Android ListView 使用 JSON 解析和 Volley

Question

我想做一个显示用户订单的 ListView。在下面的代码中，我得到了“成功”的作品，但我无法让订单数组出现。

public void getOrderList() {
    SharedPreferences sharedPreferences = getSharedPreferences("UserData", Context.MODE_PRIVATE);
    final String hpno = sharedPreferences.getString("hpno", DEFAULT);
    final OrderAdapter orderAdapter = new OrderAdapter(this, R.layout.row_layout);
    orderIdListView.setAdapter(orderAdapter);

    Response.Listener<String> responseListener = new Response.Listener<String>() {

        @Override
        public void onResponse(String response) {
            try {
                JSONObject jsonResponse = new JSONObject(response);
                boolean success = jsonResponse.getBoolean("success");

                if (success) {
                    JSONArray orderList = new JSONArray(response);
                    for (int i = 0; i < orderList.length(); i++) {
                        HashMap<String, String> map = new HashMap<String, String>();
                        JSONObject object = orderList.getJSONObject(i);
                        map.put("order_id", "Order Number: " + object.getString("order_id"));
                        orderAdapter.add(map);
                    }
                } else {
                    AlertDialog.Builder builder = new AlertDialog.Builder(ViewOrderActivity.this);
                    builder.setMessage("Order(s) Failed to be retrieved")
                            .setNegativeButton("Retry", null)
                            .create()
                            .show();
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    };

    ViewOrderRequest viewOrderRequest = new ViewOrderRequest(hpno, responseListener);
    RequestQueue queue = Volley.newRequestQueue(ViewOrderActivity.this);
    queue.add(viewOrderRequest);
}

订单适配器：

public class OrderAdapter extends ArrayAdapter {
    List list = new ArrayList();
    public OrderAdapter(Context context, int resource) {
        super(context, resource);
    }

    public void add(Order order) {
        list.add(order);
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Object getItem(int position) {
         return list.add(position);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row;
        row = convertView;
        OrderHolder orderHolder;
        if (row == null) {
            LayoutInflater layoutInflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            row = layoutInflater.inflate(R.layout.row_layout, parent, false);
            orderHolder = new OrderHolder();
            orderHolder.orderIdText = (TextView) row.findViewById(R.id.orderIdText);
            row.setTag(orderHolder);
        } else {
            orderHolder = (OrderHolder) row.getTag();
        }
        Order order = (Order) this.getItem(position);
        orderHolder.orderIdText.setText(order.getOrder_id());
        return row;
    }

    static class OrderHolder {
        TextView orderIdText;
    }
}

我的 PHP 代码：

<?php
    require "init.php";

    $hpno = $_POST['hpno'];

    $statement = mysqli_prepare($con, "SELECT * FROM `Order` WHERE hpno = ?") or die(mysqli_error($con));
    mysqli_stmt_bind_param($statement, "s", $hpno);
    mysqli_stmt_execute($statement);

    mysqli_stmt_store_result($statement);
    mysqli_stmt_bind_result($statement, $order_id, $total_price, $quantity, $payment_status, $hpno, $menu_id, $ordered_on);

    $response = array();
    $response["success"] = false;  

    while(mysqli_stmt_fetch($statement)){
        $response["success"] = true;
        array_push($response, array("order_id"=>$order_id, "total_price"=>$total_price, "quantity"=>$quantity));
    }

    echo json_encode($response);
?>

JSON 返回：

{
    "success": true,
    "0": {
        "order_id": 21,
        "total_price": 6,
        "quantity": 1
    },
    "1": {
        "order_id": 22,
        "total_price": 18,
        "quantity": 3
    },
    "2": {
        "order_id": 23,
        "total_price": 25,
        "quantity": 5
    },
    "3": {
        "order_id": 24,
        "total_price": 35,
        "quantity": 5
    }
}

LOGCAT：

04-19 22:43:17.280 15452-15452/wqyap762.rprqs W/System.err: org.json.JSONException: Value {"success":true,"0":{"order_id":21,"total_price":6,"quantity":1},"1":{"order_id":22,"total_price":18,"quantity":3},"2":{"order_id":23,"total_price":25,"quantity":5},"3":{"order_id":24,"total_price":35,"quantity":5}} of type org.json.JSONObject cannot be converted to JSONArray

错误来自这一行：

JSONArray orderList = new JSONArray(response);

我一直在使用许多方法从数据库中检索，但都不起作用。

Answer 1

您的 JSON 格式不正确。如果您希望您的代码按预期工作，您的 JSON 应该是：

{
    "success": true,
    "values": [ {
        "order_id": 21,
        "total_price": 6,
        "quantity": 1
    },
    {
        "order_id": 22,
        "total_price": 18,
        "quantity": 3
    },
    {
        "order_id": 23,
        "total_price": 25,
        "quantity": 5
    },
    {
        "order_id": 24,
        "total_price": 35,
        "quantity": 5
    }]
}

你的代码类似于：

JSONArray orderList = new JSONArray(response.getJSONArray("values"));

Answer 2

首先，您需要通知适配器的更改

if (success) {
       JSONArray orderList = new JSONArray(response);
       for (int i = 0; i < orderList.length(); i++) {
             HashMap<String, String> map = new HashMap<String, String>();
             JSONObject object = orderList.getJSONObject(i);
             map.put("order_id", "Order Number: " + object.getString("order_id"));
             orderAdapter.add(map);
        }
        oderAdapter.notifyDataSetChanged();
    }

其次，该错误很容易理解，您正在尝试将 json 解析为 JSONObject 类型的 JSONArray。

正如@Benoit 所说，您应该在从数据库中获取数据时更改您的响应，并将值作为数组获取，就像他也写的那样

这是一个问题，解释了如何将数据库结果解析为 json 数组

How to build a JSON array from mysql database