php - 如何对从 phpMyAdmin 获取数据的 ListView 进行排序

Question

我有一个简单的 Android 应用程序，它从 phpMyAdmin DB 获取数据并将其显示在 ListView 中。在我的数据库中，我有两列，第一列称为 place_name，第二列称为 Numbers_of_visits。我可以毫无问题地从数据库获取数据。

但是我在尝试根据最高访问次数(即数据库中的)对 ListView 进行排序时遇到问题，因此访问次数最高的地方应该位于顶部，依此类推。

请大家帮我做到这一点

这是我的 Jvav 代码

        package com.example.ems_project;

    import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.util.ArrayList;
    import java.util.Comparator;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;

    import org.apache.http.HttpResponse;
    import org.apache.http.client.ClientProtocolException;
    import org.apache.http.client.HttpClient;
    import org.apache.http.client.methods.HttpPost;
    import org.apache.http.impl.client.DefaultHttpClient;
    import org.json.JSONArray;
    import org.json.JSONException;
    import org.json.JSONObject;

    import android.app.Activity;
    import android.os.AsyncTask;
    import android.os.Bundle;
    import android.widget.ListView;
    import android.widget.SimpleAdapter;
    import android.widget.Toast;

    public class PlacesListView extends Activity {
        private String jsonResult;
        private String url = "http://ibrahimaldosari.t15.org/listview.php";
        private ListView listView;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.listview_main2);
            listView = (ListView) findViewById(R.id.listview);
            accessWebService();
        }

        // Async Task to access the web
        private class JsonReadTask extends AsyncTask<String, Void, String> {
            @Override
            protected String doInBackground(String... params) {
                HttpClient httpclient = new DefaultHttpClient();
                HttpPost httppost = new HttpPost(params[0]);
                try {
                    HttpResponse response = httpclient.execute(httppost);
                    jsonResult = inputStreamToString(response.getEntity().getContent()).toString();
                }

                catch (ClientProtocolException e) { 
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                return null;
            }

            private StringBuilder inputStreamToString(InputStream is) {
                String rLine = "";
                StringBuilder answer = new StringBuilder();
                BufferedReader rd = new BufferedReader(new InputStreamReader(is));

                try {
                    while ((rLine = rd.readLine()) != null) {
                        answer.append(rLine);
                    }
                }

                catch (IOException e) {
                    // e.printStackTrace();
                    Toast.makeText(getApplicationContext(), "Error..." + e.toString(), Toast.LENGTH_LONG).show();
                }
                return answer;
            }

            @Override
            protected void onPostExecute(String result) {
                ListDrwaer();
            }
        }// end async task

        public void accessWebService() {
            JsonReadTask task = new JsonReadTask();
            // passes values for the urls string array
            task.execute(new String[] { url });
        }

        // build hash set for list view
        public void ListDrwaer() {
            List<Map<String, String>> employeeList = new ArrayList<Map<String, String>>();

            try {
                JSONObject jsonResponse = new JSONObject(jsonResult);
                JSONArray jsonMainNode = jsonResponse.optJSONArray("placestable");

                for (int i = 0; i < jsonMainNode.length(); i++) {


                    JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
                    String name = jsonChildNode.optString("name");
                    int number = jsonChildNode.optInt("visit");

                    String outPut = name + "---" + number;
                    employeeList.add(createEmployee("places", outPut));

                }
            } catch (JSONException e) {
                Toast.makeText(getApplicationContext(), "Error" + e.toString(),Toast.LENGTH_SHORT).show();
            }

            SimpleAdapter simpleAdapter = new SimpleAdapter(this, employeeList, android.R.layout.simple_list_item_1, new String[] { "places" }, new int[] { android.R.id.text1 });

            listView.setAdapter(simpleAdapter);

        }

        private HashMap<String, String> createEmployee(String name, String number) {
            HashMap<String, String> employeeNameNo = new HashMap<String, String>();
            employeeNameNo.put(name, number);
            return employeeNameNo;
        }
    }

这是我正在使用的 php 文件

<?php
  $host="mysql.freehostingnoads.net"; //replace with database hostname 
   $username="u746805016_ibrr1"; //replace with database username 
  $password="113281188"; //replace with database password 
  $db_name="u746805016_ibrr1"; //replace with database name

  $con=mysql_connect("$host", "$username", "$password")or die("cannot connect"); 
  mysql_select_db("$db_name")or die("cannot select DB");
  $sql = "select * from placestable"; 
  $result = mysql_query($sql);
  $json = array();

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

Answer 1

您可以通过两种方式实现此目的。1. 在服务器端，将选择查询稍微更改为如下所示:

$sql = "从placestable中选择* ORDER BY访问DESC";

或者2. 通过在应用程序端对此进行排序。但随后我将创建带有字段的 Employee 类:姓名和访问，并实现 Comparable 接口(interface)。