php - Android:如何使我检索到的(从 mysql 中)JSON 解析数据添加到 ListView 每分钟刷新一次

Question

在下面的代码中，有一个 Activity 通过 php 从 mysql 数据库(6 个字符串)获取数据到 android 应用程序并直接到 ListView。

数据获取工作正常，我只需要 ListView 自动“自动”刷新它，并提醒用户通过声音和振动获取新数据。

将感谢您提供解决方案，在此先感谢。

P.S:我知道我正在使用来自 API 22 等的已弃用方法。

<?php

    define('HOST','my_hostname..');
    define('USERNAME','mysql username');
    define('PASSWORD','mysql password');
    define('DB','mysql db name');

    $con = mysqli_connect(HOST,USERNAME,PASSWORD,DB) or die('Unable to      

    connect');

    $sql = "select * from orders";

    $res = mysqli_query($con,$sql);

    $result = array();

   while($row = mysqli_fetch_array($res)){
   array_push($result,
   array('user'=>$row[0],'city'=>$row[1],'street'=>$row[2],          
   'streetnumber'=>$row[3],'phone'=>$row[4],'name'=>$row[5]));
   }

   echo json_encode(array("result"=>$result));

   mysqli_close($con);

   ?>

Android Studio Activity

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.BasicHttpParams;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;


public class ViewOrdersActivity extends ActionBarActivity  {

    String myJSON;

    private static final String TAG_RESULTS="result";
    private static final String TAG_USER = "user";
    private static final String TAG_CITY = "city";
    private static final String TAG_STREET ="street";
    private static final String TAG_STREETNUMBER ="streetnumber";
    private static final String TAG_PHONE ="phone";
    private static final String TAG_NAME ="name";

    JSONArray ORDERS = null;

    ArrayList<HashMap<String, String>> ordersList;

    ListView list;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_view_orders);
        list = (ListView) findViewById(R.id.listView);
        ordersList = new ArrayList<HashMap<String,String>>();

        getData();

    }



    protected void showList(){
        try {
            JSONObject jsonObj = new JSONObject(myJSON);
            ORDERS = jsonObj.getJSONArray(TAG_RESULTS);

            for(int i=0;i<ORDERS.length();i++){
                JSONObject c = ORDERS.getJSONObject(i);
                String user = c.getString(TAG_USER);
                String city = c.getString(TAG_CITY);
                String street = c.getString(TAG_STREET);
                String streetnumber = c.getString(TAG_STREETNUMBER);
                String phone = c.getString(TAG_PHONE);
                String name = c.getString(TAG_NAME);


                HashMap<String,String> orders = new HashMap<String,String>();

                orders.put(TAG_USER, user);
                orders.put(TAG_CITY, city);
                orders.put(TAG_STREET, street);
                orders.put(TAG_STREETNUMBER, streetnumber);
                orders.put(TAG_PHONE, phone);
                orders.put(TAG_NAME, name);


                ordersList.add(orders);
            }

            ListAdapter adapter = new SimpleAdapter(
                    ViewOrdersActivity.this, ordersList, R.layout.list_item,
                    new String[]{TAG_USER, TAG_CITY, TAG_STREET, TAG_STREETNUMBER, TAG_PHONE, TAG_NAME},
                    new int[]{R.id.user, R.id.city, R.id.street,R.id.streetnumber, R.id.phone , R.id.name}
            );

            list.setAdapter(adapter);
            list.invalidateViews();

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

    }


    public void getData(){
        class GetDataJSON extends AsyncTask<String, Void, String>{


            @Override
            protected String doInBackground(String... params) {

                DefaultHttpClient httpclient = new DefaultHttpClient(new BasicHttpParams());
                HttpPost httppost = new HttpPost("http://myweb/folder/myphpfile.php");

                httppost.setHeader("Content-type", "application/json");

                InputStream inputStream = null;
                String result = null;
                try {
                    HttpResponse response = httpclient.execute(httppost);
                    HttpEntity entity = response.getEntity();

                    inputStream = entity.getContent();
                    // json is UTF-8 by default
                    BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"), 8);
                    StringBuilder sb = new StringBuilder();

                    String line = null;
                    while ((line = reader.readLine()) != null)
                    {
                        sb.append(line + "\n");
                    }
                    result = sb.toString();
                } catch (Exception e) {
                    // Oops
                }
                finally {
                    try{if(inputStream != null)inputStream.close();}catch(Exception squish){}
                }
                return result;
            }

            @Override
            protected void onPostExecute(String result){
                myJSON=result;
                showList();
            }

        }

        GetDataJSON g = new GetDataJSON();
        g.execute();
    }



    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, 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();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

Answer 1

这道题可以通过两种方式完成，一种是通过 TimerTask 类，另一种是通过 Handler 类。我更喜欢 Handler one，所以我发布了如何使用 Handler

http://developer.android.com/reference/java/util/TimerTask.html

final Handler handler = new Handler()
handler.postDelayed( new Runnable() {

    @Override
    public void run() {
        YOUR_ADAPTER_GOES_HERE.notifyDataSetChanged();
        //dont forget to call getData();
        handler.postDelayed( this, 60 * 10000 ); //ensure to run after 10 minutes
    }
}, 60 * 10000 );

您只能在主 (UI) 线程中更新 UI。

通过在主线程中创建处理程序，您可以确保您发布到处理程序的所有内容也在主线程中运行。