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.GData; import com.google.gwt.gdata.client.GDataSystemPackage; import com.google.gwt.gdata.client.calendar.CalendarEntry; import com.google.gwt.gdata.client.calendar.CalendarEntryCallback; import com.google.gwt.gdata.client.calendar.CalendarFeed; import com.google.gwt.gdata.client.calendar.CalendarFeedCallback; 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 delete a calendar. */ public class CalendarDeleteCalendarDemo 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 CalendarDeleteCalendarDemo(); } @Override public String getDescription() { return "<p>This sample demonstrates how to delete an existing " + "calendar of the authenticated user. It retrieves a list of " + "the user's own calendars, and delete the first calendar with " + "title that starts with 'GWT-Calendar-Client'. The owncalendars " + "feed is used for calendar deletion.</p>"; } @Override public String getName() { return "Calendar - Deleting a calendar"; } }; } 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 retrieving the user's calendars. */ public CalendarDeleteCalendarDemo() { 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(); } } /** * Delete a calendar entry using the Calendar service and * the calendar entry uri. * On success and failure, display a status message. * * @param calendarEntryUri The uri of the calendar entry to delete */ private void deleteCalendar(String calendarEntryUri) { showStatus("Deleting calendar...", false); service.deleteEntry(calendarEntryUri, new CalendarEntryCallback() { public void onFailure(CallErrorException caught) { showStatus("An error occurred while deleting a calendar: " + caught.getMessage(), true); } public void onSuccess(CalendarEntry result) { showStatus("Deleted a calendar.", false); } }); } /** * Retrieve the calendars feed using the calendar service and * the calendars feed uri. * On success, identify the first calendar entry with a title starting * with "GWT-Calendar-Client", this will be the calendar that will be * deleted. * If no calendar is found, display a message. * Otherwise call deleteCalendar to delete the calendar. Alternatively * we could also have used targetCalendar.deleteEntry to * delete the calendar, but the effect is the same. * * @param calendarsFeedUri The uri of the calendars feed */ private void getCalendars(String calendarsFeedUri) { showStatus("Loading calendars...", false); service.getOwnCalendarsFeed(calendarsFeedUri, new CalendarFeedCallback() { public void onFailure(CallErrorException caught) { showStatus("An error occurred while retrieving the Calendar feed: " + caught.getMessage(), true); } public void onSuccess(CalendarFeed result) { CalendarEntry[] entries = result.getEntries(); if (entries.length == 0) { showStatus("You have no calendars.", false); } else { CalendarEntry targetCalendar = null; for (CalendarEntry entry : entries) { String title = entry.getTitle().getText(); if (title.startsWith("GWT-Calendar-Client")) { targetCalendar = entry; break; } } if (targetCalendar == null) { showStatus("Did not find a calendar entry whose title starts " + "with the prefix 'GWT-Calendar-Client'.", false); } else { String calendarEntryUri = targetCalendar.getSelfLink().getHref(); deleteCalendar(calendarEntryUri); } } } }); } /** * 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_DeleteCalendarDemo_v2.0"); if (User.getStatus(scope) == AuthSubStatus.LOGGED_IN) { Button startButton = new Button("Delete a calendar"); startButton.addClickHandler(new ClickHandler() { public void onClick(ClickEvent event) { getCalendars("http://www.google.com/calendar/feeds/default/" + "owncalendars/full"); } }); mainPanel.setWidget(0, 0, startButton); } else { showStatus("You are not logged on to Google Calendar.", true); } } }