Android SimpleAdapter刷新

Question

我在屏幕上刷新数据有问题，app通过JSON获取数据一切正常，但现在我需要在菜单中执行刷新按钮。我根据一个例子构建了我的应用程序。据我所知，使用SimpleAdapter并且需要编写自定义适配器是个好主意。你能帮帮我吗？

的ServiceHandler

public class ServiceHandler {
static String response = null;
public final static int GET = 1;
public final static int POST = 2;

public ServiceHandler() {

}

/*
 * Making service call
 * @url - url to make request
 * @method - http request method
 * */
public String makeServiceCall(String url, int method) {
    return this.makeServiceCall(url, method, null);
}

/*
 * Making service call
 * @url - url to make request
 * @method - http request method
 * @params - http request params
 * */
public String makeServiceCall(String url, int method,
        List<NameValuePair> params) {
    try {
        // http client
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpEntity httpEntity = null;
        HttpResponse httpResponse = null;

        // Checking http request method type
        if (method == POST) {
            HttpPost httpPost = new HttpPost(url);
            // adding post params
            if (params != null) {
                httpPost.setEntity(new UrlEncodedFormEntity(params));
            }

            httpResponse = httpClient.execute(httpPost);

        } else if (method == GET) {
            // appending params to url
            if (params != null) {
                String paramString = URLEncodedUtils
                        .format(params, "utf-8");
                url += "?" + paramString;
            }
            HttpGet httpGet = new HttpGet(url);

            httpResponse = httpClient.execute(httpGet);

        }
        httpEntity = httpResponse.getEntity();
        response = EntityUtils.toString(httpEntity);

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    return response;

}
}

MainActivity

public class MainActivity extends ListActivity {

    private ProgressDialog pDialog;

    // URL to get contacts JSON
    private static String url = "******";

    // JSON Node names
    private static final String TAG_ZLECENIA = "zlecenia";
    private static final String TAG_ID = "id";
    private static final String TAG_CO = "co";
    private static final String TAG_KYDA = "kyda";
    private static final String TAG_ILE = "ile";
    private static final String TAG_LIM = "lim_czas";


    // zlecenia JSONArray
    JSONArray zlecenia = null;

    // Hashmap for ListView
    ArrayList<HashMap<String, String>> ZleceniaList;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ZleceniaList = new ArrayList<HashMap<String, String>>();

        ListView lv = getListView();

        // Listview on item click listener
        lv.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                // getting values from selected ListItem
                String co = ((TextView) view.findViewById(R.id.co))
                        .getText().toString();
                String kyda = ((TextView) view.findViewById(R.id.kyda))
                        .getText().toString();
            }
        });

        // Calling async task to get json
        new GetContacts().execute();
    }

    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    /**
     * Async task class to get json by making HTTP call
     * */
    private class GetContacts extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            // Showing progress dialog
            pDialog = new ProgressDialog(MainActivity.this);
            pDialog.setMessage("Please wait...");
            pDialog.setCancelable(false);
            pDialog.show();

        }

        @Override
        protected Void doInBackground(Void... arg0) {
            // Creating service handler class instance
            ServiceHandler sh = new ServiceHandler();

            // Making a request to url and getting response
            String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);

            Log.d("Response: ", "> " + jsonStr);

            if (jsonStr != null) {
                try {
                    JSONObject jsonObj = new JSONObject(jsonStr);

                    // Getting JSON Array node
                    zlecenia = jsonObj.getJSONArray(TAG_ZLECENIA);

                    // looping through All Contacts
                    for (int i = 0; i < zlecenia.length(); i++) {
                        JSONObject c = zlecenia.getJSONObject(i);

                        String id = c.getString(TAG_ID);
                        String co = c.getString(TAG_CO);
                        String kyda = c.getString(TAG_KYDA);
                        String ile = c.getString(TAG_ILE);
                        String lim = c.getString(TAG_LIM);

                        // tmp hashmap for single contact
                        HashMap<String, String> zlecenia = new HashMap<String, String>();

                        // adding each child node to HashMap key => value
                        zlecenia.put(TAG_ID, id);
                        zlecenia.put(TAG_CO, co);
                        zlecenia.put(TAG_KYDA, kyda);
                        zlecenia.put(TAG_ILE, ile);
                        zlecenia.put(TAG_LIM, lim);

                        // adding contact to contact list
                        ZleceniaList.add(zlecenia);
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            } else {
                Log.e("ServiceHandler", "Couldn't get any data from the url");
            }

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);
            // Dismiss the progress dialog
            if (pDialog.isShowing())
                pDialog.dismiss();
            /**
             * Updating parsed JSON data into ListView
             * */
            ListAdapter adapter = new SimpleAdapter(
                    MainActivity.this, ZleceniaList, R.layout.list_item,
                    new String[] { TAG_KYDA, TAG_CO, TAG_ILE, TAG_LIM,},
                    new int[] { R.id.kyda, R.id.co, R.id.ile, R.id.lim });

            setListAdapter(adapter);
        }

    }

}

休息/菜单/ main.xml中

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context=".MainActivity" >
    <item
        android:id="@+id/action_refresh"
        android:showAsAction="ifRoom"
        android:title="Refresh"
        android:icon="@drawable/ic_refresh_white_36dp"

         />
</menu>

Answer 1

您必须覆盖 onOptionsItemSelected（）方法并处理刷新菜单项单击操作。