获取基于用户ID的列表视图

Question

我无法理解为什么我从中获取null listview，因为我用邮递员尝试了我的网址。我认为我的Android部分有一些问题，但我不知道问题出在哪里。

查看订单活动

public class ViewOrderActivity extends AppCompatActivity {

private ListView listView3;

private CustomAdapter2 listAdapter2;
ArrayList<Order> orderlist = new ArrayList<>();


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_view_order);
    User user = SharedPrefManager.getInstance(this).getUser();
    String str_oid=String.valueOf(user.getId());
    String type="cancel";
    BackgroundWorker backgroundWorker=new BackgroundWorker(this);
    backgroundWorker.execute(type,str_oid);
    listView3 = (ListView) findViewById(R.id.listView3);
    getJSON("http://192.168.28.1/restaurant/getorder.php");

}


private void getJSON(final String urlWebService) {

    class GetJSON extends AsyncTask<Void, Void, String> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }


        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);

            try {
                loadIntoListView(s);
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }

        @Override
        protected String doInBackground(Void... voids) {
            try {
                URL url = new URL(urlWebService);
                HttpURLConnection con = (HttpURLConnection) url.openConnection();
                StringBuilder sb = new StringBuilder();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
                String json;
                while ((json = bufferedReader.readLine()) != null) {
                    sb.append(json + "\n");
                }
                return sb.toString().trim();
            } catch (Exception e) {
                return null;
            }
        }
    }
    GetJSON getJSON = new GetJSON();
    getJSON.execute();
}

private void loadIntoListView(String json) throws JSONException {
    JSONArray jsonArray = new JSONArray(json);

    for (int i = 0; i < jsonArray.length(); i++) {
        JSONObject obj = jsonArray.getJSONObject(i);
        orderlist.add(new Order(obj.getInt("orderid"), obj.getInt("pickuptime"), obj.getInt("pickupdate")));
    }
    listAdapter2 = new CustomAdapter2(this, orderlist);
    listView3.setAdapter(listAdapter2);

  }
}

这是自定义适配器，其中列表视图是结构化的。

自定义适配器

class CustomAdapter2 extends BaseAdapter {
public ArrayList<Order> ordlists;
private Context context;
CustomAdapter2(Context context, ArrayList<Order> ordlists) {
    //super(context, R.layout.item_food, strilist);
    this.context = context;
    this.ordlists = ordlists;
}
@Override
public int getCount(){

    return ordlists.size();
}
@Override
public Order getItem(int position){
    return ordlists.get(position);
}
@Override
public long getItemId(int position){
    return 0;
}

@NonNull
@Override
public View getView(final int position, View convertView, @NonNull ViewGroup parent) {
    final ListViewHolder2 listViewHolder2;
    View customView2;
    if(convertView == null)
    {
        LayoutInflater menuInflater2 = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        // LayoutInflater menuInflater = LayoutInflater.from(getContext());
        customView2 = menuInflater2.inflate(R.layout.item_order, parent, false);
        listViewHolder2 = new ListViewHolder2();
        listViewHolder2.tvorderid = (TextView) customView2.findViewById(R.id.tvorderid );
        listViewHolder2.tvtime = (TextView) customView2.findViewById(R.id.tvtime);
        listViewHolder2.tvdate = (TextView) customView2.findViewById(R.id.tvdate);
        listViewHolder2.btncancel = (Button) customView2.findViewById(R.id.btncancel);

        customView2.setTag(listViewHolder2);
    }
    else
    {
        customView2=convertView;
        listViewHolder2= (ListViewHolder2) customView2.getTag();
    }

    final Order order=getItem(position);
    //Typeface customfont= Typeface.createFromAsset(parent.getContext().getAssets(),"fonts");
    listViewHolder2.tvorderid.setText(String.valueOf(order.getOrderid()));
    listViewHolder2.tvorderid.setTextColor(Color.YELLOW);
    listViewHolder2.tvorderid.setTextSize(10);
    listViewHolder2.tvtime.setText(String.valueOf(order.getPickuptime()));
    listViewHolder2.tvtime.setTextColor(Color.YELLOW);
    listViewHolder2.tvtime.setTextSize(10);
    listViewHolder2.tvdate.setText(String.valueOf(order.getPickupdate()));
    listViewHolder2.tvdate.setTextColor(Color.YELLOW);
    listViewHolder2.tvdate.setTextSize(10);

    listViewHolder2.btncancel.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v) {


        }
    });

    return customView2;
}

取消类型的后台工作人员

else if (type.equals("cancel")){
        try{
            String id=params[1];
            URL url=new URL(cancel_url);
            HttpURLConnection httpURLConnection=(HttpURLConnection)url.openConnection();
            httpURLConnection.setRequestMethod("POST");
            httpURLConnection.setDoOutput(true);
            httpURLConnection.setDoInput(true);
            OutputStream outputStream=httpURLConnection.getOutputStream();
            BufferedWriter bufferedWriter=new BufferedWriter(new OutputStreamWriter(outputStream,"UTF-8"));
            String post_data= URLEncoder.encode("id","UTF-8")+"="+URLEncoder.encode(id,"UTF-8");
            bufferedWriter.write(post_data);
            bufferedWriter.flush();
            bufferedWriter.close();
            outputStream.close();
            InputStream inputStream=httpURLConnection.getInputStream();
            BufferedReader bufferedReader=new BufferedReader(new InputStreamReader(inputStream,"iso-8859-1"));
            String result="";
            String line="";
            while((line=bufferedReader.readLine())!=null){
                result+=line;
            }
            bufferedReader.close();
            inputStream.close();
            httpURLConnection.disconnect();
            return result;
        }catch(MalformedURLException e){
            e.printStackTrace();
        }catch (IOException e){
            e.printStackTrace();
        }
    }

这是我的url getorder.php

的代码

<?php

$hostname = "localhost";
$username = "root";
$password = "";
$database = "y77";

$conn = new mysqli($hostname, $username, $password, $database);


if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}

$orders = array(); 
session_start();


$id=$_POST["id"];
$stmt =$conn->prepare("SELECT `orderid`, `pickuptime`, `pickupdate` FROM `order` WHERE `id`=$id");

$stmt->execute();

$stmt->bind_result($orderid, $pickuptime, $pickupdate);

while($stmt->fetch()){
$temp = [
'orderid'=>$orderid,
'pickuptime'=>$pickuptime,
'pickupdate'=>$pickupdate
];
array_push($orders, $temp);
}

echo json_encode($orders);
?>