Java tutorial
/* * Copyright 2011 Google Inc. * * 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.google.android.apps.iosched.ui; import static com.google.android.apps.iosched.util.UIUtils.buildStyledSnippet; import static com.google.android.apps.iosched.util.UIUtils.formatSessionSubtitle; import android.content.Context; import android.content.Intent; import android.database.ContentObserver; import android.database.Cursor; import android.net.Uri; import android.os.Bundle; import android.os.Handler; import android.os.SystemClock; import android.provider.BaseColumns; import android.support.v4.app.ListFragment; import android.text.Spannable; import android.util.Log; import android.view.View; import android.view.ViewGroup; import android.widget.CursorAdapter; import android.widget.ListView; import android.widget.TextView; import com.google.android.apps.iosched.provider.ScheduleContract; import com.google.android.apps.iosched.util.ActivityHelper; import com.google.android.apps.iosched.util.AnalyticsUtils; import com.google.android.apps.iosched.util.NotifyingAsyncQueryHandler; import com.google.android.apps.iosched.util.UIUtils; import com.novoda.droidcon2011.R; /** * A {@link ListFragment} showing a list of sessions. */ public class SessionsFragment extends ListFragment implements NotifyingAsyncQueryHandler.AsyncQueryListener { public static final String EXTRA_SCHEDULE_TIME_STRING = "com.google.android.iosched.extra.SCHEDULE_TIME_STRING"; private static final String STATE_CHECKED_POSITION = "checkedPosition"; private Uri mTrackUri; private Cursor mCursor; private CursorAdapter mAdapter; private int mCheckedPosition = -1; private boolean mHasSetEmptyText = false; private NotifyingAsyncQueryHandler mHandler; private Handler mMessageQueueHandler = new Handler(); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mHandler = new NotifyingAsyncQueryHandler(getActivity().getContentResolver(), this); reloadFromArguments(getArguments()); } public void reloadFromArguments(Bundle arguments) { // Teardown from previous arguments if (mCursor != null) { getActivity().stopManagingCursor(mCursor); mCursor = null; } mCheckedPosition = -1; setListAdapter(null); mHandler.cancelOperation(SearchQuery._TOKEN); mHandler.cancelOperation(SessionsQuery._TOKEN); mHandler.cancelOperation(TracksQuery._TOKEN); // Load new arguments final Intent intent = BaseActivity.fragmentArgumentsToIntent(arguments); final Uri sessionsUri = intent.getData(); final int sessionQueryToken; if (sessionsUri == null) { return; } String[] projection; if (!ScheduleContract.Sessions.isSearchUri(sessionsUri)) { mAdapter = new SessionsAdapter(getActivity()); projection = SessionsQuery.PROJECTION; sessionQueryToken = SessionsQuery._TOKEN; } else { mAdapter = new SearchAdapter(getActivity()); projection = SearchQuery.PROJECTION; sessionQueryToken = SearchQuery._TOKEN; } setListAdapter(mAdapter); // Start background query to load sessions mHandler.startQuery(sessionQueryToken, null, sessionsUri, projection, null, null, ScheduleContract.Sessions.DEFAULT_SORT); // If caller launched us with specific track hint, pass it along when // launching session details. Also start a query to load the track info. mTrackUri = intent.getParcelableExtra(SessionDetailFragment.EXTRA_TRACK); if (mTrackUri != null) { mHandler.startQuery(TracksQuery._TOKEN, mTrackUri, TracksQuery.PROJECTION); } } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE); if (savedInstanceState != null) { mCheckedPosition = savedInstanceState.getInt(STATE_CHECKED_POSITION, -1); } if (!mHasSetEmptyText) { // Could be a bug, but calling this twice makes it become visible when it shouldn't // be visible. setEmptyText(getString(R.string.empty_sessions)); mHasSetEmptyText = true; } } /** {@inheritDoc} */ public void onQueryComplete(int token, Object cookie, Cursor cursor) { if (getActivity() == null) { return; } if (token == SessionsQuery._TOKEN || token == SearchQuery._TOKEN) { onSessionOrSearchQueryComplete(cursor); } else if (token == TracksQuery._TOKEN) { onTrackQueryComplete(cursor); } else { Log.d("SessionsFragment/onQueryComplete", "Query complete, Not Actionable: " + token); cursor.close(); } } /** * Handle {@link SessionsQuery} {@link Cursor}. */ private void onSessionOrSearchQueryComplete(Cursor cursor) { if (mCursor != null) { // In case cancelOperation() doesn't work and we end up with consecutive calls to this // callback. getActivity().stopManagingCursor(mCursor); mCursor = null; } mCursor = cursor; getActivity().startManagingCursor(mCursor); mAdapter.changeCursor(mCursor); if (mCheckedPosition >= 0 && getView() != null) { getListView().setItemChecked(mCheckedPosition, true); } } /** * Handle {@link TracksQuery} {@link Cursor}. */ private void onTrackQueryComplete(Cursor cursor) { try { if (!cursor.moveToFirst()) { return; } // Use found track to build title-bar ActivityHelper activityHelper = ((BaseActivity) getActivity()).getActivityHelper(); String trackName = cursor.getString(TracksQuery.TRACK_NAME); activityHelper.setActionBarTitle(trackName); activityHelper.setActionBarColor(cursor.getInt(TracksQuery.TRACK_COLOR)); AnalyticsUtils.getInstance(getActivity()).trackPageView("/Tracks/" + trackName); } finally { cursor.close(); } } @Override public void onResume() { super.onResume(); mMessageQueueHandler.post(mRefreshSessionsRunnable); getActivity().getContentResolver().registerContentObserver(ScheduleContract.Sessions.CONTENT_URI, true, mSessionChangesObserver); if (mCursor != null) { mCursor.requery(); } } @Override public void onPause() { super.onPause(); mMessageQueueHandler.removeCallbacks(mRefreshSessionsRunnable); getActivity().getContentResolver().unregisterContentObserver(mSessionChangesObserver); } @Override public void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); outState.putInt(STATE_CHECKED_POSITION, mCheckedPosition); } /** {@inheritDoc} */ @Override public void onListItemClick(ListView l, View v, int position, long id) { // Launch viewer for specific session, passing along any track knowledge // that should influence the title-bar. final Cursor cursor = (Cursor) mAdapter.getItem(position); final String sessionId = cursor.getString(cursor.getColumnIndex(ScheduleContract.Sessions.SESSION_ID)); final Uri sessionUri = ScheduleContract.Sessions.buildSessionUri(sessionId); final Intent intent = new Intent(Intent.ACTION_VIEW, sessionUri); intent.putExtra(SessionDetailFragment.EXTRA_TRACK, mTrackUri); ((BaseActivity) getActivity()).openActivityOrFragment(intent); getListView().setItemChecked(position, true); mCheckedPosition = position; } public void clearCheckedPosition() { if (mCheckedPosition >= 0) { getListView().setItemChecked(mCheckedPosition, false); mCheckedPosition = -1; } } /** * {@link CursorAdapter} that renders a {@link SessionsQuery}. */ private class SessionsAdapter extends CursorAdapter { public SessionsAdapter(Context context) { super(context, null); } /** {@inheritDoc} */ @Override public View newView(Context context, Cursor cursor, ViewGroup parent) { return getActivity().getLayoutInflater().inflate(R.layout.list_item_session, parent, false); } /** {@inheritDoc} */ @Override public void bindView(View view, Context context, Cursor cursor) { final TextView titleView = (TextView) view.findViewById(R.id.session_title); final TextView subtitleView = (TextView) view.findViewById(R.id.session_subtitle); titleView.setText(cursor.getString(SessionsQuery.TITLE)); // Format time block this session occupies final long blockStart = cursor.getLong(SessionsQuery.BLOCK_START); final long blockEnd = cursor.getLong(SessionsQuery.BLOCK_END); final String roomName = cursor.getString(SessionsQuery.ROOM_NAME); final String subtitle = formatSessionSubtitle(blockStart, blockEnd, roomName, context); subtitleView.setText(subtitle); final boolean starred = cursor.getInt(SessionsQuery.STARRED) != 0; view.findViewById(R.id.star_button).setVisibility(starred ? View.VISIBLE : View.INVISIBLE); // Possibly indicate that the session has occurred in the past. UIUtils.setSessionTitleColor(blockStart, blockEnd, titleView, subtitleView); } } /** * {@link CursorAdapter} that renders a {@link SearchQuery}. */ private class SearchAdapter extends CursorAdapter { public SearchAdapter(Context context) { super(context, null); } /** {@inheritDoc} */ @Override public View newView(Context context, Cursor cursor, ViewGroup parent) { return getActivity().getLayoutInflater().inflate(R.layout.list_item_session, parent, false); } /** {@inheritDoc} */ @Override public void bindView(View view, Context context, Cursor cursor) { ((TextView) view.findViewById(R.id.session_title)).setText(cursor.getString(SearchQuery.TITLE)); final String snippet = cursor.getString(SearchQuery.SEARCH_SNIPPET); final Spannable styledSnippet = buildStyledSnippet(snippet); ((TextView) view.findViewById(R.id.session_subtitle)).setText(styledSnippet); final boolean starred = cursor.getInt(SearchQuery.STARRED) != 0; view.findViewById(R.id.star_button).setVisibility(starred ? View.VISIBLE : View.INVISIBLE); } } private ContentObserver mSessionChangesObserver = new ContentObserver(new Handler()) { @Override public void onChange(boolean selfChange) { if (mCursor != null) { mCursor.requery(); } } }; private Runnable mRefreshSessionsRunnable = new Runnable() { public void run() { if (mAdapter != null) { // This is used to refresh session title colors. mAdapter.notifyDataSetChanged(); } // Check again on the next quarter hour, with some padding to account for network // time differences. long nextQuarterHour = (SystemClock.uptimeMillis() / 900000 + 1) * 900000 + 5000; mMessageQueueHandler.postAtTime(mRefreshSessionsRunnable, nextQuarterHour); } }; /** * {@link com.google.android.apps.iosched.provider.ScheduleContract.Sessions} query parameters. */ private interface SessionsQuery { int _TOKEN = 0x1; String[] PROJECTION = { BaseColumns._ID, ScheduleContract.Sessions.SESSION_ID, ScheduleContract.Sessions.SESSION_TITLE, ScheduleContract.Sessions.SESSION_STARRED, ScheduleContract.Blocks.BLOCK_START, ScheduleContract.Blocks.BLOCK_END, ScheduleContract.Rooms.ROOM_NAME, }; int _ID = 0; int SESSION_ID = 1; int TITLE = 2; int STARRED = 3; int BLOCK_START = 4; int BLOCK_END = 5; int ROOM_NAME = 6; } /** * {@link com.google.android.apps.iosched.provider.ScheduleContract.Tracks} query parameters. */ private interface TracksQuery { int _TOKEN = 0x2; String[] PROJECTION = { ScheduleContract.Tracks.TRACK_NAME, ScheduleContract.Tracks.TRACK_COLOR, }; int TRACK_NAME = 0; int TRACK_COLOR = 1; } /** {@link com.google.android.apps.iosched.provider.ScheduleContract.Sessions} search query * parameters. */ private interface SearchQuery { int _TOKEN = 0x3; String[] PROJECTION = { BaseColumns._ID, ScheduleContract.Sessions.SESSION_ID, ScheduleContract.Sessions.SESSION_TITLE, ScheduleContract.Sessions.SEARCH_SNIPPET, ScheduleContract.Sessions.SESSION_STARRED, }; int _ID = 0; int SESSION_ID = 1; int TITLE = 2; int SEARCH_SNIPPET = 3; int STARRED = 4; } }