Java tutorial
/* * Copyright 2012 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 es.tor.push.android; import static es.tor.push.android.Constants.GCM_SEND_ENDPOINT; import static es.tor.push.android.Constants.JSON_CANONICAL_IDS; import static es.tor.push.android.Constants.JSON_ERROR; import static es.tor.push.android.Constants.JSON_FAILURE; import static es.tor.push.android.Constants.JSON_MESSAGE_ID; import static es.tor.push.android.Constants.JSON_MULTICAST_ID; import static es.tor.push.android.Constants.JSON_PAYLOAD; import static es.tor.push.android.Constants.JSON_REGISTRATION_IDS; import static es.tor.push.android.Constants.JSON_RESULTS; import static es.tor.push.android.Constants.JSON_SUCCESS; import static es.tor.push.android.Constants.PARAM_COLLAPSE_KEY; import static es.tor.push.android.Constants.PARAM_DELAY_WHILE_IDLE; import static es.tor.push.android.Constants.PARAM_PAYLOAD_PREFIX; import static es.tor.push.android.Constants.PARAM_REGISTRATION_ID; import static es.tor.push.android.Constants.PARAM_TIME_TO_LIVE; import static es.tor.push.android.Constants.TOKEN_CANONICAL_REG_ID; import static es.tor.push.android.Constants.TOKEN_ERROR; import static es.tor.push.android.Constants.TOKEN_MESSAGE_ID; import es.tor.push.android.Result.Builder; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStream; import java.net.HttpURLConnection; import java.net.URL; import java.net.URLEncoder; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Map.Entry; import java.util.Random; import java.util.logging.Level; import java.util.logging.Logger; import com.fasterxml.jackson.core.type.TypeReference; import com.fasterxml.jackson.databind.ObjectMapper; /** * Helper class to send messages to the GCM service using an API Key. */ public class Sender { protected static final String UTF8 = "UTF-8"; /** * Initial delay before first retry, without jitter. */ protected static final int BACKOFF_INITIAL_DELAY = 1000; /** * Maximum delay before a retry. */ protected static final int MAX_BACKOFF_DELAY = 1024000; protected final Random random = new Random(); protected final Logger logger = Logger.getLogger(getClass().getName()); private final String key = "AIzaSyBClMwWCcJMuajUNoEeCwQidPflqoPvgIM"; /** * Sends a message to one device, retrying in case of unavailability. * * <p> * <strong>Note: </strong> this method uses exponential back-off to retry in * case of service unavailability and hence could block the calling thread * for many seconds. * * @param message * message to be sent, including the device's registration id. * @param registrationId * device where the message will be sent. * @param retries * number of retries in case of service unavailability errors. * * @return result of the request (see its javadoc for more details) * * @throws IllegalArgumentException * if registrationId is {@literal null}. * @throws InvalidRequestException * if GCM didn't returned a 200 or 503 status. * @throws IOException * if message could not be sent. */ public Result send(Message message, String registrationId, int retries) throws IOException { int attempt = 0; Result result = null; int backoff = BACKOFF_INITIAL_DELAY; boolean tryAgain; do { attempt++; if (logger.isLoggable(Level.FINE)) { logger.fine("Attempt #" + attempt + " to send message " + message + " to regIds " + registrationId); } result = sendNoRetry(message, registrationId); tryAgain = result == null && attempt <= retries; if (tryAgain) { int sleepTime = backoff / 2 + random.nextInt(backoff); sleep(sleepTime); if (2 * backoff < MAX_BACKOFF_DELAY) { backoff *= 2; } } } while (tryAgain); if (result == null) { throw new IOException("Could not send message after " + attempt + " attempts"); } return result; } /** * Sends a message without retrying in case of service unavailability. See * {@link #send(Message, String, int)} for more info. * * @return result of the post, or {@literal null} if the GCM service was * unavailable. * * @throws InvalidRequestException * if GCM didn't returned a 200 or 503 status. * @throws IllegalArgumentException * if registrationId is {@literal null}. */ public Result sendNoRetry(Message message, String registrationId) throws IOException { StringBuilder body = newBody(PARAM_REGISTRATION_ID, registrationId); Boolean delayWhileIdle = message.isDelayWhileIdle(); if (delayWhileIdle != null) { addParameter(body, PARAM_DELAY_WHILE_IDLE, delayWhileIdle ? "1" : "0"); } String collapseKey = message.getCollapseKey(); if (collapseKey != null) { addParameter(body, PARAM_COLLAPSE_KEY, collapseKey); } Integer timeToLive = message.getTimeToLive(); if (timeToLive != null) { addParameter(body, PARAM_TIME_TO_LIVE, Integer.toString(timeToLive)); } for (Entry<String, String> entry : message.getData().entrySet()) { String key = PARAM_PAYLOAD_PREFIX + entry.getKey(); String value = entry.getValue(); addParameter(body, key, URLEncoder.encode(value, UTF8)); } String requestBody = body.toString(); logger.finest("Request body: " + requestBody); HttpURLConnection conn = post(GCM_SEND_ENDPOINT, requestBody); int status = conn.getResponseCode(); if (status == 503) { logger.fine("GCM service is unavailable"); return null; } if (status != 200) { throw new InvalidRequestException(status); } try { BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream())); try { String line = reader.readLine(); if (line == null || line.equals("")) { throw new IOException("Received empty response from GCM service."); } String[] responseParts = split(line); String token = responseParts[0]; String value = responseParts[1]; if (token.equals(TOKEN_MESSAGE_ID)) { Builder builder = new Result.Builder().messageId(value); // check for canonical registration id line = reader.readLine(); if (line != null) { responseParts = split(line); token = responseParts[0]; value = responseParts[1]; if (token.equals(TOKEN_CANONICAL_REG_ID)) { builder.canonicalRegistrationId(value); } else { logger.warning("Received invalid second line from GCM: " + line); } } Result result = builder.build(); if (logger.isLoggable(Level.FINE)) { logger.fine("Message created succesfully (" + result + ")"); } return result; } else if (token.equals(TOKEN_ERROR)) { return new Result.Builder().errorCode(value).build(); } else { throw new IOException("Received invalid response from GCM: " + line); } } finally { reader.close(); } } finally { conn.disconnect(); } } /** * Sends a message to many devices, retrying in case of unavailability. * * <p> * <strong>Note: </strong> this method uses exponential back-off to retry in * case of service unavailability and hence could block the calling thread * for many seconds. * * @param message * message to be sent. * @param regIds * registration id of the devices that will receive the message. * @param retries * number of retries in case of service unavailability errors. * * @return combined result of all requests made. * * @throws IllegalArgumentException * if registrationIds is {@literal null} or empty. * @throws InvalidRequestException * if GCM didn't returned a 200 or 503 status. * @throws IOException * if message could not be sent. */ public MulticastResult send(Message message, List<String> regIds, int retries) throws IOException { int attempt = 0; MulticastResult multicastResult = null; int backoff = BACKOFF_INITIAL_DELAY; // Map of results by registration id, it will be updated after each // attempt // to send the messages Map<String, Result> results = new HashMap<String, Result>(); List<String> unsentRegIds = new ArrayList<String>(regIds); boolean tryAgain; List<Long> multicastIds = new ArrayList<Long>(); do { attempt++; if (logger.isLoggable(Level.FINE)) { logger.fine("Attempt #" + attempt + " to send message " + message + " to regIds " + unsentRegIds); } multicastResult = sendNoRetry(message, unsentRegIds); long multicastId = multicastResult.getMulticastId(); logger.fine("multicast_id on attempt # " + attempt + ": " + multicastId); multicastIds.add(multicastId); unsentRegIds = updateStatus(unsentRegIds, results, multicastResult); tryAgain = !unsentRegIds.isEmpty() && attempt <= retries; if (tryAgain) { int sleepTime = backoff / 2 + random.nextInt(backoff); sleep(sleepTime); if (2 * backoff < MAX_BACKOFF_DELAY) { backoff *= 2; } } } while (tryAgain); // calculate summary int success = 0, failure = 0, canonicalIds = 0; for (Result result : results.values()) { if (result.getMessageId() != null) { success++; if (result.getCanonicalRegistrationId() != null) { canonicalIds++; } } else { failure++; } } // build a new object with the overall result long multicastId = multicastIds.remove(0); MulticastResult.Builder builder = new MulticastResult.Builder(success, failure, canonicalIds, multicastId) .retryMulticastIds(multicastIds); // add results, in the same order as the input for (String regId : regIds) { Result result = results.get(regId); builder.addResult(result); } return builder.build(); } /** * Updates the status of the messages sent to devices and the list of * devices that should be retried. * * @param unsentRegIds * list of devices that are still pending an update. * @param allResults * map of status that will be updated. * @param multicastResult * result of the last multicast sent. * * @return updated version of devices that should be retried. */ private List<String> updateStatus(List<String> unsentRegIds, Map<String, Result> allResults, MulticastResult multicastResult) { List<Result> results = multicastResult.getResults(); if (results.size() != unsentRegIds.size()) { // should never happen, unless there is a flaw in the algorithm throw new RuntimeException("Internal error: sizes do not match. " + "currentResults: " + results + "; unsentRegIds: " + unsentRegIds); } List<String> newUnsentRegIds = new ArrayList<String>(); for (int i = 0; i < unsentRegIds.size(); i++) { String regId = unsentRegIds.get(i); Result result = results.get(i); allResults.put(regId, result); String error = result.getErrorCodeName(); if (error != null && error.equals(Constants.ERROR_UNAVAILABLE)) { newUnsentRegIds.add(regId); } } return newUnsentRegIds; } /** * Sends a message without retrying in case of service unavailability. See * {@link #send(Message, List, int)} for more info. * * @return {@literal true} if the message was sent successfully, * {@literal false} if it failed but could be retried. * * @throws IllegalArgumentException * if registrationIds is {@literal null} or empty. * @throws InvalidRequestException * if GCM didn't returned a 200 status. * @throws IOException * if message could not be sent or received. */ public MulticastResult sendNoRetry(Message message, List<String> registrationIds) throws IOException { if (nonNull(registrationIds).isEmpty()) { throw new IllegalArgumentException("registrationIds cannot be empty"); } Map<String, Object> jsonRequest = new HashMap<String, Object>(); jsonRequest.put(PARAM_TIME_TO_LIVE, message.getTimeToLive()); jsonRequest.put(PARAM_COLLAPSE_KEY, message.getCollapseKey()); jsonRequest.put(PARAM_DELAY_WHILE_IDLE, message.isDelayWhileIdle()); jsonRequest.put(JSON_REGISTRATION_IDS, registrationIds); Map<String, String> payload = message.getData(); if (!payload.isEmpty()) { jsonRequest.put(JSON_PAYLOAD, payload); } ObjectMapper mapper = new ObjectMapper(); String requestBody = mapper.writeValueAsString(jsonRequest); // JSONValue.toJSONString(jsonRequest); logger.finest("JSON request: " + requestBody); HttpURLConnection conn = post(GCM_SEND_ENDPOINT, "application/json", requestBody); int status = conn.getResponseCode(); String responseBody; if (status != 200) { responseBody = getString(conn.getErrorStream()); logger.finest("JSON error response: " + responseBody); throw new InvalidRequestException(status, responseBody); } responseBody = getString(conn.getInputStream()); logger.finest("JSON response: " + responseBody); Map<String, Object> jsonResponse = mapper.readValue(responseBody, new TypeReference<Map<String, Object>>() { }); /*Map<String, Object> jsonResponse = gson.fromJson(requestBody, new TypeToken<Map<String, Object>>() { }.getType());*/ int success = (Integer) jsonResponse.get(JSON_SUCCESS); int failure = (Integer) jsonResponse.get(JSON_FAILURE); int canonicalIds = (Integer) jsonResponse.get(JSON_CANONICAL_IDS); long multicastId = (Long) jsonResponse.get(JSON_MULTICAST_ID); MulticastResult.Builder builder = new MulticastResult.Builder(success, failure, canonicalIds, multicastId); @SuppressWarnings("unchecked") List<Map<String, Object>> results = (List<Map<String, Object>>) jsonResponse.get(JSON_RESULTS); if (results != null) { for (Map<String, Object> jsonResult : results) { String messageId = (String) jsonResult.get(JSON_MESSAGE_ID); String canonicalRegId = (String) jsonResult.get(TOKEN_CANONICAL_REG_ID); String error = (String) jsonResult.get(JSON_ERROR); Result result = new Result.Builder().messageId(messageId).canonicalRegistrationId(canonicalRegId) .errorCode(error).build(); builder.addResult(result); } } MulticastResult multicastResult = builder.build(); return multicastResult; } private String[] split(String line) throws IOException { String[] split = line.split("=", 2); if (split.length != 2) { throw new IOException("Received invalid response line from GCM: " + line); } return split; } /** * Make an HTTP post to a given URL. * * @return HTTP response. */ protected HttpURLConnection post(String url, String body) throws IOException { return post(url, "application/x-www-form-urlencoded;charset=UTF-8", body); } protected HttpURLConnection post(String url, String contentType, String body) throws IOException { if (url == null || body == null) { throw new IllegalArgumentException("arguments cannot be null"); } if (!url.startsWith("https://")) { logger.warning("URL does not use https: " + url); } logger.fine("Sending POST to " + url); logger.finest("POST body: " + body); byte[] bytes = body.getBytes(); HttpURLConnection conn = getConnection(url); conn.setDoOutput(true); conn.setUseCaches(false); conn.setFixedLengthStreamingMode(bytes.length); conn.setRequestMethod("POST"); conn.setRequestProperty("Content-Type", contentType); conn.setRequestProperty("Authorization", "key=" + key); OutputStream out = conn.getOutputStream(); out.write(bytes); out.close(); return conn; } /** * Creates a map with just one key-value pair. */ protected static final Map<String, String> newKeyValues(String key, String value) { Map<String, String> keyValues = new HashMap<String, String>(1); keyValues.put(nonNull(key), nonNull(value)); return keyValues; } /** * Creates a {@link StringBuilder} to be used as the body of an HTTP POST. * * @param name * initial parameter for the POST. * @param value * initial value for that parameter. * @return StringBuilder to be used an HTTP POST body. */ protected static StringBuilder newBody(String name, String value) { return new StringBuilder(nonNull(name)).append('=').append(nonNull(value)); } /** * Adds a new parameter to the HTTP POST body. * * @param body * HTTP POST body * @param name * parameter's name * @param value * parameter's value */ protected static void addParameter(StringBuilder body, String name, String value) { nonNull(body).append('&').append(nonNull(name)).append('=').append(nonNull(value)); } /** * Gets an {@link HttpURLConnection} given an URL. */ protected HttpURLConnection getConnection(String url) throws IOException { HttpURLConnection conn = (HttpURLConnection) new URL(url).openConnection(); return conn; } /** * Convenience method to convert an InputStream to a String. * * <p> * If the stream ends in a newline character, it will be stripped. */ protected static String getString(InputStream stream) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(nonNull(stream))); StringBuilder content = new StringBuilder(); String newLine; do { newLine = reader.readLine(); if (newLine != null) { content.append(newLine).append('\n'); } } while (newLine != null); if (content.length() > 0) { // strip last newline content.setLength(content.length() - 1); } return content.toString(); } static <T> T nonNull(T argument) { if (argument == null) { throw new IllegalArgumentException("argument cannot be null"); } return argument; } void sleep(long millis) { try { Thread.sleep(millis); } catch (InterruptedException e) { Thread.currentThread().interrupt(); } } }