/*
* Copyright 2013 The Android Open Source Project
*
* 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.example.android.basicsyncadapter;
import android.accounts.Account;
import android.annotation.TargetApi;
import android.app.Activity;
import android.content.ContentResolver;
import android.content.Intent;
import android.content.SyncStatusObserver;
import android.database.Cursor;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;
import android.support.v4.widget.SimpleCursorAdapter;
import android.text.format.Time;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.ListView;
import android.widget.TextView;
import com.example.android.common.accounts.GenericAccountService;
import com.example.android.basicsyncadapter.provider.FeedContract;
/**
* List fragment containing a list of Atom entry objects (articles) stored in the local database.
*
* <p>Database access is mediated by a content provider, specified in
* {@link com.example.android.basicsyncadapter.provider.FeedProvider}. This content
* provider is
* automatically populated by {@link SyncService}.
*
* <p>Selecting an item from the displayed list displays the article in the default browser.
*
* <p>If the content provider doesn't return any data, then the first sync hasn't run yet. This sync
* adapter assumes data exists in the provider once a sync has run. If your app doesn't work like
* this, you should add a flag that notes if a sync has run, so you can differentiate between "no
* available data" and "no initial sync", and display this in the UI.
*
* <p>The ActionBar displays a "Refresh" button. When the user clicks "Refresh", the sync adapter
* runs immediately. An indeterminate ProgressBar element is displayed, showing that the sync is
* occurring.
*/
public class EntryListFragment extends ListFragment
implements LoaderManager.LoaderCallbacks<Cursor> {
private static final String TAG = "EntryListFragment";
/**
* Cursor adapter for controlling ListView results.
*/
private SimpleCursorAdapter mAdapter;
/**
* Handle to a SyncObserver. The ProgressBar element is visible until the SyncObserver reports
* that the sync is complete.
*
* <p>This allows us to delete our SyncObserver once the application is no longer in the
* foreground.
*/
private Object mSyncObserverHandle;
/**
* Options menu used to populate ActionBar.
*/
private Menu mOptionsMenu;
/**
* Projection for querying the content provider.
*/
private static final String[] PROJECTION = new String[]{
FeedContract.Entry._ID,
FeedContract.Entry.COLUMN_NAME_TITLE,
FeedContract.Entry.COLUMN_NAME_LINK,
FeedContract.Entry.COLUMN_NAME_PUBLISHED
};
// Column indexes. The index of a column in the Cursor is the same as its relative position in
// the projection.
/** Column index for _ID */
private static final int COLUMN_ID = 0;
/** Column index for title */
private static final int COLUMN_TITLE = 1;
/** Column index for link */
private static final int COLUMN_URL_STRING = 2;
/** Column index for published */
private static final int COLUMN_PUBLISHED = 3;
/**
* List of Cursor columns to read from when preparing an adapter to populate the ListView.
*/
private static final String[] FROM_COLUMNS = new String[]{
FeedContract.Entry.COLUMN_NAME_TITLE,
FeedContract.Entry.COLUMN_NAME_PUBLISHED
};
/**
* List of Views which will be populated by Cursor data.
*/
private static final int[] TO_FIELDS = new int[]{
android.R.id.text1,
android.R.id.text2};
/**
* Mandatory empty constructor for the fragment manager to instantiate the
* fragment (e.g. upon screen orientation changes).
*/
public EntryListFragment() {}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
}
/**
* Create SyncAccount at launch, if needed.
*
* <p>This will create a new account with the system for our application, register our
* {@link SyncService} with it, and establish a sync schedule.
*/
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
// Create account, if needed
SyncUtils.CreateSyncAccount(activity);
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
mAdapter = new SimpleCursorAdapter(
getActivity(), // Current context
android.R.layout.simple_list_item_activated_2, // Layout for individual rows
null, // Cursor
FROM_COLUMNS, // Cursor columns to use
TO_FIELDS, // Layout fields to use
0 // No flags
);
mAdapter.setViewBinder(new SimpleCursorAdapter.ViewBinder() {
@Override
public boolean setViewValue(View view, Cursor cursor, int i) {
if (i == COLUMN_PUBLISHED) {
// Convert timestamp to human-readable date
Time t = new Time();
t.set(cursor.getLong(i));
((TextView) view).setText(t.format("%Y-%m-%d %H:%M"));
return true;
} else {
// Let SimpleCursorAdapter handle other fields automatically
return false;
}
}
});
setListAdapter(mAdapter);
setEmptyText(getText(R.string.loading));
getLoaderManager().initLoader(0, null, this);
}
@Override
public void onResume() {
super.onResume();
mSyncStatusObserver.onStatusChanged(0);
// Watch for sync state changes
final int mask = ContentResolver.SYNC_OBSERVER_TYPE_PENDING |
ContentResolver.SYNC_OBSERVER_TYPE_ACTIVE;
mSyncObserverHandle = ContentResolver.addStatusChangeListener(mask, mSyncStatusObserver);
}
@Override
public void onPause() {
super.onPause();
if (mSyncObserverHandle != null) {
ContentResolver.removeStatusChangeListener(mSyncObserverHandle);
mSyncObserverHandle = null;
}
}
/**
* Query the content provider for data.
*
* <p>Loaders do queries in a background thread. They also provide a ContentObserver that is
* triggered when data in the content provider changes. When the sync adapter updates the
* content provider, the ContentObserver responds by resetting the loader and then reloading
* it.
*/
@Override
public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
// We only have one loader, so we can ignore the value of i.
// (It'll be '0', as set in onCreate().)
return new CursorLoader(getActivity(), // Context
FeedContract.Entry.CONTENT_URI, // URI
PROJECTION, // Projection
null, // Selection
null, // Selection args
FeedContract.Entry.COLUMN_NAME_PUBLISHED + " desc"); // Sort
}
/**
* Move the Cursor returned by the query into the ListView adapter. This refreshes the existing
* UI with the data in the Cursor.
*/
@Override
public void onLoadFinished(Loader<Cursor> cursorLoader, Cursor cursor) {
mAdapter.changeCursor(cursor);
}
/**
* Called when the ContentObserver defined for the content provider detects that data has
* changed. The ContentObserver resets the loader, and then re-runs the loader. In the adapter,
* set the Cursor value to null. This removes the reference to the Cursor, allowing it to be
* garbage-collected.
*/
@Override
public void onLoaderReset(Loader<Cursor> cursorLoader) {
mAdapter.changeCursor(null);
}
/**
* Create the ActionBar.
*/
@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
super.onCreateOptionsMenu(menu, inflater);
mOptionsMenu = menu;
inflater.inflate(R.menu.main, menu);
}
/**
* Respond to user gestures on the ActionBar.
*/
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
// If the user clicks the "Refresh" button.
case R.id.menu_refresh:
SyncUtils.TriggerRefresh();
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* Load an article in the default browser when selected by the user.
*/
@Override
public void onListItemClick(ListView listView, View view, int position, long id) {
super.onListItemClick(listView, view, position, id);
// Get a URI for the selected item, then start an Activity that displays the URI. Any
// Activity that filters for ACTION_VIEW and a URI can accept this. In most cases, this will
// be a browser.
// Get the item at the selected position, in the form of a Cursor.
Cursor c = (Cursor) mAdapter.getItem(position);
// Get the link to the article represented by the item.
String articleUrlString = c.getString(COLUMN_URL_STRING);
if (articleUrlString == null) {
Log.e(TAG, "Attempt to launch entry with null link");
return;
}
Log.i(TAG, "Opening URL: " + articleUrlString);
// Get a Uri object for the URL string
Uri articleURL = Uri.parse(articleUrlString);
Intent i = new Intent(Intent.ACTION_VIEW, articleURL);
startActivity(i);
}
/**
* Set the state of the Refresh button. If a sync is active, turn on the ProgressBar widget.
* Otherwise, turn it off.
*
* @param refreshing True if an active sync is occuring, false otherwise
*/
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public void setRefreshActionButtonState(boolean refreshing) {
if (mOptionsMenu == null || Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB) {
return;
}
final MenuItem refreshItem = mOptionsMenu.findItem(R.id.menu_refresh);
if (refreshItem != null) {
if (refreshing) {
refreshItem.setActionView(R.layout.actionbar_indeterminate_progress);
} else {
refreshItem.setActionView(null);
}
}
}
/**
* Crfate a new anonymous SyncStatusObserver. It's attached to the app's ContentResolver in
* onResume(), and removed in onPause(). If status changes, it sets the state of the Refresh
* button. If a sync is active or pending, the Refresh button is replaced by an indeterminate
* ProgressBar; otherwise, the button itself is displayed.
*/
private SyncStatusObserver mSyncStatusObserver = new SyncStatusObserver() {
/** Callback invoked with the sync adapter status changes. */
@Override
public void onStatusChanged(int which) {
getActivity().runOnUiThread(new Runnable() {
/**
* The SyncAdapter runs on a background thread. To update the UI, onStatusChanged()
* runs on the UI thread.
*/
@Override
public void run() {
// Create a handle to the account that was created by
// SyncService.CreateSyncAccount(). This will be used to query the system to
// see how the sync status has changed.
Account account = GenericAccountService.GetAccount(SyncUtils.ACCOUNT_TYPE);
if (account == null) {
// GetAccount() returned an invalid value. This shouldn't happen, but
// we'll set the status to "not refreshing".
setRefreshActionButtonState(false);
return;
}
// Test the ContentResolver to see if the sync adapter is active or pending.
// Set the state of the refresh button accordingly.
boolean syncActive = ContentResolver.isSyncActive(
account, FeedContract.CONTENT_AUTHORITY);
boolean syncPending = ContentResolver.isSyncPending(
account, FeedContract.CONTENT_AUTHORITY);
setRefreshActionButtonState(syncActive || syncPending);
}
});
}
};
}