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.Fragment; import android.os.AsyncTask; import android.os.Bundle; import android.util.Log; import android.view.ContextMenu; import android.view.LayoutInflater; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.ViewGroup; import android.widget.AbsListView; import android.widget.AdapterView; import android.widget.ListAdapter; import android.widget.TextView; import com.royclarkson.springagram.model.ItemResource; 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 Fragment} that displays a list of {@link ItemResource}s * * @author Roy Clarkson */ public class PhotoListFragment extends Fragment implements AbsListView.OnItemClickListener { public static final String TAG = PhotoListFragment.class.getSimpleName(); private static final String ARG_PHOTO_LIST_URL = "photos_url"; private String photosUrl; private PhotoListFragmentListener photoListFragmentListener; private AbsListView listView; private ListAdapter listAdapter; public PhotoListFragment() { // Required empty public constructor } public static PhotoListFragment newInstance(String photosUrl) { PhotoListFragment fragment = new PhotoListFragment(); Bundle args = new Bundle(); args.putString(ARG_PHOTO_LIST_URL, photosUrl); fragment.setArguments(args); return fragment; } //*************************************** // Fragment methods //*************************************** @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); if (getArguments() != null) { this.photosUrl = getArguments().getString(ARG_PHOTO_LIST_URL); } fetchPhotoList(); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.fragment_photo, container, false); this.listView = (AbsListView) view.findViewById(android.R.id.list); this.listView.setOnItemClickListener(this); registerForContextMenu(this.listView); return view; } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); setRetainInstance(true); } /** * The default content for this Fragment has a TextView that is shown when * the list is empty. If you would like to change the text, call this method * to supply the text it should use. */ public void setEmptyText(CharSequence emptyText) { View emptyView = listView.getEmptyView(); if (emptyText instanceof TextView) { ((TextView) emptyView).setText(emptyText); } } @Override public void onAttach(Activity activity) { super.onAttach(activity); try { this.photoListFragmentListener = (PhotoListFragmentListener) activity; } catch (ClassCastException e) { throw new ClassCastException(activity.toString() + " must implement OnPhotoSelectedListener"); } } @Override public void onDetach() { super.onDetach(); this.photoListFragmentListener = 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.photo_list_context_menu, menu); } @Override public boolean onContextItemSelected(MenuItem item) { AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo) item.getMenuInfo(); switch (item.getItemId()) { case R.id.action_add_to_gallery: addToGallery(info.position); return true; case R.id.action_delete: deletePhoto(info.position); return true; default: return super.onContextItemSelected(item); } } //*************************************** // OnItemClickListener methods //*************************************** @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { if (null != this.photoListFragmentListener) { this.photoListFragmentListener.onPhotoSelected(position); } } //*************************************** // Listener interface //*************************************** public interface PhotoListFragmentListener { public void onDownloadPhotosComplete(List<ItemResource> photos); public void onPhotoSelected(int position); public ItemResource getPhotoByPosition(int position); public void onDeletePhotoByPosition(int position); public void onPhotoAddToGallerySelected(int position); public void onNetworkError(String message); } //*************************************** // Private methods //*************************************** public void fetchPhotoList() { new DownloadPhotosTask().execute(this.photosUrl); } private void refreshPhotoList(Resources resources) { if (resources != null) { List<ItemResource> photos = new ArrayList<ItemResource>(resources.getContent()); if (null != this.photoListFragmentListener) { this.photoListFragmentListener.onDownloadPhotosComplete(photos); } listAdapter = new PhotoListAdapter(getActivity(), photos); listView.setAdapter(listAdapter); } } private void deletePhoto(int position) { ItemResource itemResource = this.photoListFragmentListener.getPhotoByPosition(position); new DeletePhotoTask().execute(itemResource.getLink(ItemResource.REL_SELF).getHref()); this.photoListFragmentListener.onDeletePhotoByPosition(position); ((PhotoListAdapter) listAdapter).notifyDataSetChanged(); } private void addToGallery(int position) { this.photoListFragmentListener.onPhotoAddToGallerySelected(position); } //*************************************** // Private classes //*************************************** private class DownloadPhotosTask extends AsyncTask<String, Void, Resources> { private Exception exception; @Override protected Resources doInBackground(String... params) { try { final String url = params[0]; ParameterizedTypeReference<Resources<ItemResource>> typeRef = new ParameterizedTypeReference<Resources<ItemResource>>() { }; RestTemplate restTemplate = RestUtils.getInstance(); ResponseEntity<Resources<ItemResource>> responseEntity = restTemplate.exchange(url, HttpMethod.GET, RestUtils.getRequestEntity(), typeRef); 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) { photoListFragmentListener.onNetworkError(this.exception.getMessage()); } else { refreshPhotoList(resources); } } } private class DeletePhotoTask extends AsyncTask<String, Void, Void> { 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) { photoListFragmentListener.onNetworkError(this.exception.getMessage()); } } } }