Android选择查询JSON无限循环每10秒

Question

早上好，向所有人致以问候，我是Android JAVA的新手，在网上搜索，我找到了一个java android类，通过JSON和PHP在mysql中查询数据库，现在我正在尝试，它是每10秒钟无休止地进行一次咨询。 搜索互联网，评论以下代码，但不知道如何实现它... 任何帮助，评论，非常感谢，问候

这是该类的代码：

public class VerA extends ActionBarActivity {

String myJSON;

private static final String TAG_RESULTS="result";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "nombre";
private static final String TAG_ADD ="telefono";
private Handler mHandler;
private int mInterval = 8000; // 5 seconds by default, can be changed later


JSONArray peoples = null;

ArrayList<HashMap<String, String>> personList;

ListView list;




@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    list = (ListView) findViewById(R.id.listView);
    personList = new ArrayList<HashMap<String,String>>();
    mHandler = new Handler();
    startRepeatingTask();
    getData();



}




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

        for(int i=0;i<peoples.length();i++){
            JSONObject c = peoples.getJSONObject(i);
            String id = c.getString(TAG_ID);
            String name = c.getString(TAG_NAME);
            String address = c.getString(TAG_ADD);

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

            persons.put(TAG_ID,id);
            persons.put(TAG_NAME,name);
            persons.put(TAG_ADD,address);

            personList.add(persons);
        }

        ListAdapter adapter = new SimpleAdapter(
                VerA.this, personList, R.layout.list_item,
                new String[]{TAG_ID,TAG_NAME,TAG_ADD},
                new int[]{R.id.id, R.id.name, R.id.address}
        );

        list.setAdapter(adapter);

    } 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://tuescuelanoticias.x10.mx/selectAllJSON.php");

            // Depends on your web service
            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();
}


///course method, which should refresh the query on the base dedatos every 8 seconds

Runnable mStatusChecker = new Runnable() {
    @Override
    public void run() {
        getData();
        mHandler.postDelayed(mStatusChecker, mInterval);
    }
};
void startRepeatingTask() {
    mStatusChecker.run();
}
}

更新代码：

 public class VerA extends ActionBarActivity {

String myJSON;
private static final String TAG_RESULTS="result";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "nombre";
private static final String TAG_ADD ="telefono";
Handler handler = new Handler();
JSONArray peoples = null;

ArrayList<HashMap<String, String>> personList;

ListView list;




@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    list = (ListView) findViewById(R.id.listView);
    personList = new ArrayList<HashMap<String,String>>();
    getData();
    handler.postDelayed(runnable, 8000);


}



  // METODO QUE MUESTRA LA LISTA O LA MATRIZ
protected void showList(){
    try {
        JSONObject jsonObj = new JSONObject(myJSON);
        peoples = jsonObj.getJSONArray(TAG_RESULTS);

        for(int i=0;i<peoples.length();i++){
            JSONObject c = peoples.getJSONObject(i);
            String id = c.getString(TAG_ID);
            String name = c.getString(TAG_NAME);
            String address = c.getString(TAG_ADD);

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

            persons.put(TAG_ID,id);
            persons.put(TAG_NAME,name);
            persons.put(TAG_ADD,address);

            personList.add(persons);
        }

        ListAdapter adapter = new SimpleAdapter(
                VerA.this, personList, R.layout.list_item,
                new String[]{TAG_ID,TAG_NAME,TAG_ADD},
                new int[]{R.id.id, R.id.name, R.id.address}
        );

        list.setAdapter(adapter);

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

}


   ///METODO QUE EXTRAE LOS DATOS DE EL JASON PHP
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://tuescuelanoticias.x10.mx/selectAllJSON.php");

            // Depends on your web service
            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();
}


  ///LOS METODOS SIGUIENTES MUESTRAN LA OPCION DE MENU Y CONFIGRUACIO
@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);

}

  ///DISQUE PARA QUE SE REFRESQUE CADA 8 SEGUNDOS, AL PARECER SI TRAE LOS         DATOS PERO NO LOS DIBUJA
 private Runnable runnable = new Runnable() {
public void run() {
    showList();
        // Do some updates
        handler.postDelayed(this, 8000);

}
  };


 }

或如何在我的代码中实现AnsyTask

Answer 1

基本上，您正在寻找能够每10秒检查一次数据库的服务。如果有新数据，那么它将获取该数据。为此，您可以使用服务创建一个扩展Service类覆盖onstartCommand（）方法的类，并在此方法内部编写您的网络请求代码，不要忘记用户线程，否则服务将花费更多时间。如果您要创建一个不可销毁的服务，如果重新启动移动设备，该服务将不会被杀死，那么您应该返回Service.START_STICKY。

AlarmManager alarmManager=(AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(context, AlarmReceiver.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intent, 0);
alarmManager.setRepeating(AlarmManager.RTC_WAKEUP,System.currentTimeMillis(),100000,                                                                 pendingIntent);

通过这种方式，您可以每10秒间隔进行一次网络呼叫。但是在几秒钟内执行服务并不是一个好习惯，因为它会耗尽你的电池。