Java tutorial
/* * Copyright 2011 Google Inc. All Rights Reserved. * * 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.walkaround.wave.server.rpc; import com.google.common.net.UriEscapers; import com.google.gdata.client.contacts.ContactsService; import com.google.gdata.data.Link; import com.google.gdata.data.contacts.ContactEntry; import com.google.gdata.data.contacts.ContactFeed; import com.google.gdata.data.extensions.Email; import com.google.gdata.util.ServiceException; import com.google.gson.JsonArray; import com.google.gson.JsonObject; import com.google.gson.JsonPrimitive; import com.google.inject.Inject; import com.google.inject.Provider; import com.google.walkaround.util.server.servlet.AbstractHandler; import com.google.walkaround.util.server.servlet.BadRequestException; import com.google.walkaround.wave.server.auth.UserContext; import com.google.walkaround.wave.shared.SharedConstants; import org.waveprotocol.wave.model.util.Pair; import org.waveprotocol.wave.model.wave.ParticipantId; import java.io.IOException; import java.io.PrintWriter; import java.net.URL; import java.util.List; import java.util.logging.Logger; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * Serves contact information for the signed-in user. * * @author hearnden@google.com (David Hearnden) */ public final class ContactsHandler extends AbstractHandler { @SuppressWarnings("unused") private static final Logger log = Logger.getLogger(ContactsHandler.class.getName()); private final static int MAX_SIZE = com.google.walkaround.wave.shared.ContactsService.MAX_SIZE; private static final String FEED_URL = "https://www.google.com/m8/feeds/contacts/"; private static final String PHOTO_URL = "https://www.google.com/m8/feeds/photos/media/"; @Inject ParticipantId user; @Inject UserContext userContext; // Lazy because it will fail to instantiate if we don't have OAuth credentials. @Inject Provider<ContactsService> contacts; @Override public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException { String encodedAddress = UriEscapers.uriEscaper().escape(user.getAddress()); if (!userContext.hasOAuthCredentials()) { // Return an empty set of contacts; the client will show unknown avatars // and never call PhotosHandler. printJson(new ContactFeed(), encodedAddress, resp); return; } Pair<Integer, Integer> range = getRange(req); log.info("Fetching contacts for: " + user + ", [" + range.first + ", " + range.second + ")"); URL url = new URL(FEED_URL + encodedAddress + "/thin" + "?start-index=" + range.first + "&max-results=" + (range.second - range.first)); ContactFeed results; try { results = contacts.get().getFeed(url, ContactFeed.class); } catch (ServiceException e) { throw new IOException("Contact fetch failed: ", e); } log.info("Fetched " + results.getEntries().size() + " contacts for " + user); // Support ?format=html for debugging. if ("html".equals(req.getParameter("format"))) { printHtml(results, encodedAddress, resp); } else { printJson(results, encodedAddress, resp); } } /** * Gets the request range, and validates it. */ private static Pair<Integer, Integer> getRange(HttpServletRequest req) throws BadRequestException { String fromStr = req.getParameter("from"); String toStr = req.getParameter("to"); int from; int to; try { from = fromStr != null ? Integer.parseInt(fromStr) : 1; to = toStr != null ? Integer.parseInt(toStr) : (from + MAX_SIZE); } catch (NumberFormatException e) { throw new BadRequestException("Range not numeric: " + req.getQueryString(), e); } if (1 > from || from > to) { throw new BadRequestException("Invalid range: [" + from + ", " + to + ")"); } if (to > from + MAX_SIZE) { throw new BadRequestException("Range too large (max " + MAX_SIZE + "): [" + from + ", " + to + ")"); } assert from <= to && to <= from + MAX_SIZE; return Pair.of(from, to); } /** * Prints a contact feed as pretty HTML into a servlet response. This feature * is only for debugging. */ private void printHtml(ContactFeed results, String encodedAddress, HttpServletResponse resp) throws IOException { PrintWriter pw = resp.getWriter(); pw.println("<html>"); pw.println("<body>"); for (ContactEntry e : results.getEntries()) { pw.println("<p>"); pw.println("<img src='/photos" + shortPhotoUrl(encodedAddress, e.getContactPhotoLink()) + "'>"); pw.println(e.getTitle().getPlainText()); pw.println("</p>"); } pw.println("</body>"); pw.println("</html>"); } /** * Prints a contact feed as JSON into a servlet response. */ private void printJson(ContactFeed results, String encodedAddress, HttpServletResponse resp) throws IOException { // Since the fetch API is index based, this handler must return exactly one // result per contact entry. If a contact has 0 email addresses, then an // empty contact is returned, since without the email address, the // information is useless. If a contact has >1 email addresses, a contact // object based on just the first one is returned, due to the // exactly-one-result-per-feed-entry constraint. JsonArray res = new JsonArray(); for (ContactEntry e : results.getEntries()) { JsonObject contact = new JsonObject(); List<Email> emails = e.getEmailAddresses(); if (!emails.isEmpty()) { contact.add("a", new JsonPrimitive(emails.get(0).getAddress())); contact.add("n", new JsonPrimitive(e.getTitle().getPlainText())); contact.add("p", new JsonPrimitive(shortPhotoUrl(encodedAddress, e.getContactPhotoLink()))); } res.add(contact); } resp.getWriter().print(SharedConstants.XSSI_PREFIX + "(" + res.toString() + ")"); } /** * Produces a possibly-shortened path for a contact's photo. * * @param encodedAddress url-encoded address of the viewer * @param link contact link */ private String shortPhotoUrl(String encodedAddress, Link link) { String baseUrl = PHOTO_URL + encodedAddress; String href = link.getHref(); return href.startsWith(baseUrl) ? href.substring(baseUrl.length()) : href; } }