Java tutorial
/* * Copyright 2014 Roy Clarkson * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.royclarkson.springagram; import android.app.Activity; import android.app.ListFragment; import android.os.AsyncTask; import android.os.Bundle; import android.util.Log; import android.view.ContextMenu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.widget.AdapterView; import android.widget.ListAdapter; import android.widget.ListView; import com.royclarkson.springagram.model.GalleryResource; import org.springframework.core.ParameterizedTypeReference; import org.springframework.hateoas.Resources; import org.springframework.http.HttpMethod; import org.springframework.http.ResponseEntity; import org.springframework.web.client.ResourceAccessException; import org.springframework.web.client.RestTemplate; import java.util.ArrayList; import java.util.List; /** * {@link ListFragment} that displays a list of {@link GalleryResource}s * * @author Roy Clarkson */ public class GalleryListFragment extends ListFragment { public static final String TAG = GalleryListFragment.class.getSimpleName(); private static final String ARG_GALLERIES_LIST_URL = "galleries_url"; private String galleriesUrl; private GalleryListFragmentListener galleryListFragmentListener; public GalleryListFragment() { // Required empty public constructor } public static GalleryListFragment newInstance(String galleriesUrl) { GalleryListFragment fragment = new GalleryListFragment(); Bundle args = new Bundle(); args.putString(ARG_GALLERIES_LIST_URL, galleriesUrl); fragment.setArguments(args); return fragment; } //*************************************** // Fragment methods //*************************************** @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); if (getArguments() != null) { this.galleriesUrl = getArguments().getString(ARG_GALLERIES_LIST_URL); } fetchGalleryList(); } @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); registerForContextMenu(this.getListView()); } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); setRetainInstance(true); } @Override public void onAttach(Activity activity) { super.onAttach(activity); try { galleryListFragmentListener = (GalleryListFragmentListener) activity; } catch (ClassCastException e) { throw new ClassCastException( activity.toString() + " must implement OnGalleryFragmentInteractionListener"); } } @Override public void onDetach() { super.onDetach(); galleryListFragmentListener = null; } @Override public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) { super.onCreateContextMenu(menu, v, menuInfo); MenuInflater inflater = new MenuInflater(this.getActivity()); inflater.inflate(R.menu.gallery_list_context_menu, menu); } @Override public boolean onContextItemSelected(MenuItem item) { AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo) item.getMenuInfo(); switch (item.getItemId()) { case R.id.action_delete: deleteGallery(info.position); return true; default: return super.onContextItemSelected(item); } } //*************************************** // ListFragment methods //*************************************** @Override public void onListItemClick(ListView l, View v, int position, long id) { super.onListItemClick(l, v, position, id); if (null != this.galleryListFragmentListener) { this.galleryListFragmentListener.onGallerySelected(position); } } //*************************************** // Private methods //*************************************** public void fetchGalleryList() { new DownloadGalleriesTask().execute(this.galleriesUrl); } private void refreshGalleryList(Resources resources) { if (resources != null) { List<GalleryResource> galleries = new ArrayList<GalleryResource>(resources.getContent()); if (null != this.galleryListFragmentListener) { this.galleryListFragmentListener.onDownloadGalleriesComplete(galleries); } ListAdapter listAdapter = new GalleryListAdapter(getActivity(), galleries); setListAdapter(listAdapter); } } private void deleteGallery(int position) { GalleryResource galleryResource = this.galleryListFragmentListener.getGalleryByPosition(position); new DeleteGalleryTask().execute(galleryResource.getLink("self").getHref()); this.galleryListFragmentListener.onDeleteGalleryByPosition(position); ((GalleryListAdapter) getListAdapter()).notifyDataSetChanged(); } // *************************************** // Listener interface // *************************************** public interface GalleryListFragmentListener { public void onDownloadGalleriesComplete(List<GalleryResource> galleries); public void onGallerySelected(int position); public GalleryResource getGalleryByPosition(int position); public void onDeleteGalleryByPosition(int position); public void onNetworkError(String message); } // *************************************** // Private classes // *************************************** private class DownloadGalleriesTask extends AsyncTask<String, Void, Resources> { Exception exception; @Override protected Resources doInBackground(String... params) { try { final String url = params[0]; RestTemplate restTemplate = RestUtils.getInstance(); ResponseEntity<Resources<GalleryResource>> responseEntity = restTemplate.exchange(url, HttpMethod.GET, RestUtils.getRequestEntity(), new ParameterizedTypeReference<Resources<GalleryResource>>() { }); return responseEntity.getBody(); } catch (Exception e) { this.exception = e; Log.e(TAG, e.getMessage(), e); return null; } } @Override protected void onPostExecute(Resources resources) { if (this.exception != null && this.exception instanceof ResourceAccessException) { galleryListFragmentListener.onNetworkError(this.exception.getMessage()); } else { refreshGalleryList(resources); } } } private class DeleteGalleryTask extends AsyncTask<String, Void, Void> { private Exception exception; @Override protected Void doInBackground(String... params) { try { final String url = params[0]; RestTemplate restTemplate = RestUtils.getInstance(); restTemplate.delete(url); } catch (Exception e) { this.exception = e; Log.e(TAG, e.getMessage(), e); } return null; } @Override protected void onPostExecute(Void v) { if (this.exception != null && this.exception instanceof ResourceAccessException) { galleryListFragmentListener.onNetworkError(this.exception.getMessage()); } } } }