Java tutorial
/* * Copyright 2008 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.gwt.gdata.sample.hellogdata.client; import com.google.gwt.accounts.client.AuthSubStatus; import com.google.gwt.accounts.client.User; import com.google.gwt.event.dom.client.ClickEvent; import com.google.gwt.event.dom.client.ClickHandler; import com.google.gwt.gdata.client.EventEntry; import com.google.gwt.gdata.client.EventEntryCallback; import com.google.gwt.gdata.client.GData; import com.google.gwt.gdata.client.GDataSystemPackage; import com.google.gwt.gdata.client.atom.Text; import com.google.gwt.gdata.client.calendar.CalendarEventEntry; import com.google.gwt.gdata.client.calendar.CalendarEventFeed; import com.google.gwt.gdata.client.calendar.CalendarEventFeedCallback; import com.google.gwt.gdata.client.calendar.CalendarEventQuery; import com.google.gwt.gdata.client.calendar.CalendarService; import com.google.gwt.gdata.client.impl.CallErrorException; import com.google.gwt.user.client.ui.Button; import com.google.gwt.user.client.ui.FlexTable; import com.google.gwt.user.client.ui.Label; /** * The following example demonstrates how to update a Calendar event. */ public class CalendarUpdateEventDemo extends GDataDemo { /** * This method is used by the main sample app to obtain * information on this sample and a sample instance. * * @return An instance of this demo. */ public static GDataDemoInfo init() { return new GDataDemoInfo() { @Override public GDataDemo createInstance() { return new CalendarUpdateEventDemo(); } @Override public String getDescription() { return "<p>This sample demonstrates how to update the title " + "of an existing event. A full text query is used to locate " + "an event with a title/description containing " + "'GWT-Calendar-Client', where the first match " + "is updated with the new title. The private/full feed is " + "used for the event update.</p>"; } @Override public String getName() { return "Calendar - Updating an event"; } }; } private CalendarService service; private FlexTable mainPanel; private final String scope = "http://www.google.com/calendar/feeds/"; /** * Setup the Calendar service and create the main content panel. * If the user is not logged on to Calendar display a message, * otherwise start the demo by querying the user's calendar events. */ public CalendarUpdateEventDemo() { mainPanel = new FlexTable(); initWidget(mainPanel); if (!GData.isLoaded(GDataSystemPackage.CALENDAR)) { showStatus("Loading the GData Calendar package...", false); GData.loadGDataApi(GDATA_API_KEY, new Runnable() { public void run() { startDemo(); } }, GDataSystemPackage.CALENDAR); } else { startDemo(); } } /** * Retrieves a Calendar events feed using a Query object. * In GData, feed URIs can contain querystring parameters. The * GData query objects aid in building parameterized feed URIs. * On success, identify the first event entry with a title starting * with "GWT-Calendar-Client", this will be the event that will be updated. * If no event is found, display a message. * Otherwise call updateEvent to update the event. * * @param eventsFeedUri The uri of the events feed */ private void queryEvents(String eventsFeedUri) { showStatus("Querying for events...", false); CalendarEventQuery query = CalendarEventQuery.newInstance(eventsFeedUri); query.setFullTextQuery("GWT-Calendar-Client"); service.getEventsFeed(query, new CalendarEventFeedCallback() { public void onFailure(CallErrorException caught) { showStatus("An error occurred while retrieving the Event feed: " + caught.getMessage(), true); } public void onSuccess(CalendarEventFeed result) { CalendarEventEntry[] entries = (CalendarEventEntry[]) result.getEntries(); if (entries.length == 0) { showStatus("No events found containing the text 'GWT-Calendar-Client'.", false); } else { CalendarEventEntry targetEvent = null; for (CalendarEventEntry entry : entries) { String title = entry.getTitle().getText(); if (title.startsWith("GWT-Calendar-Client")) { targetEvent = entry; break; } } if (targetEvent == null) { showStatus("Did not find a event entry whose title starts with " + "the prefix 'GWT-Calendar-Client'.", false); } else { updateEvent(targetEvent); } } } }); } /** * Displays a status message to the user. * * @param message The message to display. * @param isError Indicates whether the status is an error status. */ private void showStatus(String message, boolean isError) { mainPanel.clear(); mainPanel.insertRow(0); mainPanel.addCell(0); Label msg = new Label(message); if (isError) { msg.setStylePrimaryName("hm-error"); } mainPanel.setWidget(0, 0, msg); } /** * Starts this demo. */ private void startDemo() { service = CalendarService.newInstance("HelloGData_Calendar_UpdateEventDemo_v12.0"); if (User.getStatus(scope) == AuthSubStatus.LOGGED_IN) { Button startButton = new Button("Update an event"); startButton.addClickHandler(new ClickHandler() { public void onClick(ClickEvent event) { queryEvents("http://www.google.com/calendar/feeds/default/private/full"); } }); mainPanel.setWidget(0, 0, startButton); } else { showStatus("You are not logged on to Google Calendar.", true); } } /** * Update an event by making use of the updateEntry * method of the Entry class. * Set the event's title to an arbitrary string. Here * we prefix the title with 'GWT-Calendar-Client' so that * we can identify which events were updated by this demo. * On success and failure, display a status message. * * @param targetEvent The event entry which to update */ private void updateEvent(CalendarEventEntry targetEvent) { targetEvent.setTitle(Text.newInstance()); targetEvent.getTitle().setText("GWT-Calendar-Client - updated event"); showStatus("Updating a Calendar event...", false); targetEvent.updateEntry(new EventEntryCallback() { public void onFailure(CallErrorException caught) { showStatus("An error occurred while updating a Calendar event: " + caught.getMessage(), true); } public void onSuccess(EventEntry result) { showStatus("Updated a Calendar event.", false); } }); } }