AndroidC2DM(推送技术).doc

Android C2DM云端推送一基础知识当我们开发需要和服务器交互的应用程序时，基本上都需要获取服务器端的数据，比如地震及时通就需要及时获取服务器上最新的地震信息。要获取服务器上不定时更新的信息一般来说有两种方法，第一种是客户端使用Pull（拉）的方式，隔一段时间就去服务器上获取信息，看是否有更新的信息出现。第二种就是服务器使用Push（推送）的方式，当服务器端有新信息了，则把最新的信息Push到客户端上。虽然Pull和Push两种方式都能实现获取服务器端更新信息的功能，但是明显来说Push is better than pull。因为Pull方式更费客户端的网络流量，更主要的是费电量。Android从2.2版本开始增加了Cloud to Device Messaging（C2DM）框架，在系统中支持了Push功能，基于Android平台使用Push功能更加简单了。虽然C2DM目前还处在实验室阶段，不过小规模的使用应该没问题下面我们就来体验一下Android的C2DM功能。二C2DM框架使用Android的C2DM功能有几个要求：1. 需要Android2.2及以上的系统版本。2. 使用C2DM功能的Android设备上需要设置好Google的账户。3. 需要在这里注册使用C2DM功能的用户邮箱账号（最好为C2DM单独注册一个Gmail邮箱账号）。我们接下来C2DM的一个完整过程，这里借用一下Google官方推出的Chrome To Phone过程图来说明下。 图1 C2DM操作过程图要使用C2DM来进行Push操作，基本上要使用以下6个步骤： （1）注册：Android设备把使用C2DM功能的用户账户（比如）和App名称发送给C2DM服务器。 （2）C2DM服务器会返回一个registration_id值给Android设备，设备需要保存这个registration_id值。 （3）Android设备把获得的registration_id和C2DM功能的用户账户（）发送给自己的服务器，不过一般用户账户信息因为和服务器确定好的，所以不必发送。这样Android设备就完成了C2DM功能的注册过程，接下来就可以接收C2DM服务器Push过来的消息了。 （4）服务器获得数据。这里图中的例子Chrome To Phone，服务器接收到Chrome浏览器发送的数据。数据也可以是服务器本地产生的。这里的服务器是Google AppEngine（很好的一项服务，可惜在国内被屏了），要换成自己的服务器。服务器还要获取注册使用C2DM功能的用户账户（）的ClientLogin权限Auth。 （5）服务器把要发送的数据和registration_id一起，并且头部带上获取的Auth，使用POST的方式发送给C2DM服务器。 （6）C2DM服务器会以Push的方式把数据发送给对应的Android设备，Android设备只要在程序中按之前和服务器商量好的格式从对应的key中获取数据即可。 这样我们就大概明白了C2DM的工作流程，下面我们就结合一个实例来具体的说明以上6个步骤。三实例开发我们要创建的程序名称为AndroidC2DMDemo，包名为com.ichliebephone.c2dm。开始之前我们先去C2DM网页上注册一下使用C2DM功能的用户账户。 其中应用程序名要填写带包名的完整名称，比如这里为om.ichliebephone.c2dm. AndroidC2DMDemo。 这里的contact邮箱使用一个你能接收到邮件的邮箱即可，下面的Role（sender）account邮箱最好单独注册一个Gmail邮箱来使用C2DM服务。我们这里使用的是专门注册的邮箱。 提交后，过一段时间就会收到Google发送过来的确认邮件，然后你就可以使用C2DM的Push服务了。 介绍了这么多，我们先来快速完成一个实例，只完成Android设备端的注册部分，不包含向服务器发送registration_id和服务器向C2DM服务器发送数据的具体代码，这部分只是用Ubuntu下的curl命令来模拟，主要是快速亲自体验一下Push的结果。创建一个Android工程AndroidC2DMDemo，并且包含进Google的开源例子Chrome To Phone中的c2dm包com.google.android.c2dm，包中包含三个Java类，分别为：第一个类为C2DMBaseReceiver：java view plaincopy1 /* 2 * Copyright 2010 Google Inc. 3 * 4 * Licensed under the Apache License, Version 2.0 (the License); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * /licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an AS IS BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.android.c2dm; 18 19 import java.io.IOException; 20 21 import android.app.AlarmManager; 22 import android.app.IntentService; 23 import android.app.PendingIntent; 24 import android.content.Context; 25 import android.content.Intent; 26 import android.os.PowerManager; 27 import android.util.Log; 28 29 /* 30 * Base class for C2D message receiver. Includes constants for the 31 * strings used in the protocol. 32 */ 33 /* 34 * 接收和处理C2DM消息的基类 35 * */ 36 public abstract class C2DMBaseReceiver extends IntentService 37 /和C2DM Push的Intent内容相关 38 /重新向C2DM服务器注册 39 private static final String C2DM_RETRY = ent.RETRY; 40 /向C2DM服务器注册后的回调处理 41 public static final String REGISTRATION_CALLBACK_INTENT = ent.REGISTRATION; 42 /接收到C2DM服务器的推送消息 43 private static final String C2DM_INTENT = ent.RECEIVE; 44 45 / Logging tag 46 private static final String TAG = C2DM; 47 48 / Extras in the registration callback intents. 49 /向C2DM注册返回的intent中包含的key 50 public static final String EXTRA_UNREGISTERED = unregistered; 51 public static final String EXTRA_ERROR = error; 52 public static final String EXTRA_REGISTRATION_ID = registration_id; 53 /向C2DM注册出错的原因 54 public static final String ERR_SERVICE_NOT_AVAILABLE = SERVICE_NOT_AVAILABLE; 55 public static final String ERR_ACCOUNT_MISSING = ACCOUNT_MISSING; 56 public static final String ERR_AUTHENTICATION_FAILED = AUTHENTICATION_FAILED; 57 public static final String ERR_TOO_MANY_REGISTRATIONS = TOO_MANY_REGISTRATIONS; 58 public static final String ERR_INVALID_PARAMETERS = INVALID_PARAMETERS; 59 public static final String ERR_INVALID_SENDER = INVALID_SENDER; 60 public static final String ERR_PHONE_REGISTRATION_ERROR = PHONE_REGISTRATION_ERROR; 61 62 / wakelock 63 private static final String WAKELOCK_KEY = C2DM_LIB; 64 65 private static PowerManager.WakeLock mWakeLock; 66 private final String senderId; 67 68 /* 69 * The C2DMReceiver class must create a no-arg constructor and pass the 70 * sender id to be used for registration. 71 */ 72 public C2DMBaseReceiver(String senderId) 73 / senderId is used as base name for threads, etc. 74 super(senderId); 75 this.senderId = senderId; 76 77 /下面几个是接收到C2DM Push过来的信息后的回调函数，都可以在继承的子类中处理 78 /* 79 * Called when a cloud message has been received. 80 */ 81 /* 82 * 接收到C2DM服务器Push的消息后的回调函数，需要在继承的子类中处理 83 * */ 84 protected abstract void onMessage(Context context, Intent intent); 85 86 /* 87 * Called on registration error. Override to provide better 88 * error messages. 89 * 90 * This is called in the context of a Service - no dialog or UI. 91 */ 92 /* 93 * 出错的回调函数 94 * */ 95 public abstract void onError(Context context, String errorId); 96 97 /* 98 * Called when a registration token has been received. 99 */ 100 /* 101 * 注册后的回调函数 102 * */ 103 public void onRegistered(Context context, String registrationId) throws IOException 104 / registrationId will also be saved 105 106 107 /* 108 * Called when the device has been unregistered. 109 */ 110 /* 111 * 取消注册的回调函数 112 * */ 113 public void onUnregistered(Context context) 114 115 116 /IntentService的方法 117 Override 118 public final void onHandleIntent(Intent intent) 119 try 120 Context context = getApplicationContext(); 121 if (intent.getAction().equals(REGISTRATION_CALLBACK_INTENT) 122 handleRegistration(context, intent);/处理注册后的回调 123 else if (intent.getAction().equals(C2DM_INTENT) 124 onMessage(context, intent);/处理C2DM Push消息的回调 125 else if (intent.getAction().equals(C2DM_RETRY) 126 C2DMessaging.register(context, senderId); /重新注册 127 128 finally 129 / Release the power lock, so phone can get back to sleep. 130 / The lock is reference counted by default, so multiple 131 / messages are ok. 132 133 / If the onMessage() needs to spawn a thread or do something else, 134 / it should use its own lock. 135 mWakeLock.release(); 136 137 138 139 140 /* 141 * Called from the broadcast receiver. 142 * Will process the received intent, call handleMessage(), registered(), etc. 143 * in background threads, with a wake lock, while keeping the service 144 * alive. 145 */ 146 static void runIntentInService(Context context, Intent intent) 147 if (mWakeLock = null) 148 / This is called from BroadcastReceiver, there is no init. 149 PowerManager pm = 150 (PowerManager) context.getSystemService(Context.POWER_SERVICE); 151 mWakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, 152 WAKELOCK_KEY); 153 154 mWakeLock.acquire(); 155 156 / Use a naming convention, similar with how permissions and intents are 157 / used. Alternatives are introspection or an ugly use of statics. 158 String receiver = context.getPackageName() + .C2DMReceiver; 159 intent.setClassName(context, receiver); 160 161 context.startService(intent); 162 163 164 165 /处理注册后的回调 166 private void handleRegistration(final Context context, Intent intent) 167 final String registrationId = intent.getStringExtra(EXTRA_REGISTRATION_ID); 168 String error = intent.getStringExtra(EXTRA_ERROR); 169 String removed = intent.getStringExtra(EXTRA_UNREGISTERED); 170 Log.v(TAG, handleRegistration); 171 /打印出接收到的registraton_id 172 Log.v(TAG, dmControl: registrationId = + registrationId + 173 , error = + error + , removed = + removed); 174 if (Log.isLoggable(TAG, Log.DEBUG) 175 Log.d(TAG, dmControl: registrationId = + registrationId + 176 , error = + error + , removed = + removed); 177 178 if (removed != null) 179 / Remember we are unregistered 180 C2DMessaging.clearRegistrationId(context); 181 onUnregistered(context); 182 return; 183 else if (error != null) 184 / we are not registered, can try again 185 C2DMessaging.clearRegistrationId(context); 186 / Registration failed 187 Log.e(TAG, Registration error + error); 188 onError(context, error); 189 if (SERVICE_NOT_AVAILABLE.equals(error) 190 long backoffTimeMs = C2DMessaging.getBackoff(context); 191 192 Log.d(TAG, Scheduling registration retry, backoff = + backoffTimeMs); 193 Intent retryIntent = new Intent(C2DM_RETRY); 194 PendingIntent retryPIntent = PendingIntent.getBroadcast(context, 195 0 /*requestCode*/, retryIntent, 0 /*flags*/); 196 197 AlarmManager am = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE); 198 am.set(AlarmManager.ELAPSED_REALTIME, 199 backoffTimeMs, retryPIntent); 200 201 / Next retry should wait longer. 202 backoffTimeMs *= 2; 203 C2DMessaging.setBackoff(context, backoffTimeMs); 204 205 else 206 try 207 onRegistered(context, registrationId); 208 C2DMessaging.setRegistrationId(context, registrationId); 209 catch (IOException ex) 210 Log.e(TAG, Registration error + ex.getMessage(); 211 212 213 214 第二个类为C2DMBroadcastReceiver：java view plaincopy215 /* 216 */ 217 package com.google.android.c2dm; 218 219 import android.app.Activity; 220 import android.content.BroadcastReceiver; 221 import android.content.Context; 222 import android.content.Intent; 223 224 /* 225 * Helper class to handle BroadcastReciver behavior. 226 * - can only run for a limited amount of time - it must start a real service 227 * for longer activity 228 * - must get the power lock, must make sure its released when all done. 229 * 230 */ 231 /* 232 * 帮助类，帮忙处理BroadcastReciver过程 233 * */ 234 public class C2DMBroadcastReceiver extends BroadcastReceiver 235 236 Override 237 public final void onReceive(Context context, Intent intent) 238 / To keep things in one place. 239 C2DMBaseReceiver.runIntentInService(context, intent); 240 setResult(Activity.RESULT_OK, null /* data */, null /* extra */); 241 242 第三个类为C2DMessaging：java view plaincopy243 /* 244 * Copyright 2010 Google Inc. 245 * 246 * Licensed under the Apache License, Version 2.0 (the License); 247 * you may not use this file except in compliance with the License. 248 * You may obtain a copy of the License at 249 * 250 * /licenses/LICENSE-2.0 251 * 252 * Unless required by applicable law or agreed to in writing, software 253 * distributed under the License is distributed on an AS IS BASIS, 254 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 255 * See the License for the specific language governing permissions and 256 * limitations under the License. 257 */ 258 259 package com.google.android.c2dm; 260 261 import android.app.PendingIntent; 262 import android.content.Context; 263 import android.content.Intent; 264 import android.content.SharedPreferences; 265 import android.content.SharedPreferences.Editor; 266 267 /* 268 * Utilities for device registration. 269 * 270 * Will keep track of the registration token in a private preference. 271 */ 272 /* 273 * 和注册相关的一些实用函数 274 * */ 275 public class C2DMessaging 276 public static final String EXTRA_SENDER = sender; 277 public static final String EXTRA_APPLICATION_PENDING_INTENT = app; 278 public static final String REQUEST_UNREGISTRATION_INTENT = ent.UNREGISTER; 279 public static final String REQUEST_REGISTRATION_INTENT = ent.REGISTER; 280 public static final String LAST_REGISTRATION_CHANGE = last_registration_change; 281 public static final String BACKOFF = backoff; 282 public static final String GSF_PACKAGE = com.google.android.gsf; /GSF为GoogleServicesFramework.apk的缩写 283 284 285 / package 286 static final String PREFERENCE = com.google.android.c2dm; 287 288 private static final long DEFAULT_BACKOFF = 30000; 289 290 /* 291 * Initiate c2d messaging registration for the current application 292 */ 293 public static void register(Context context, 294 String senderId) 295 Intent registrationIntent = new Intent(REQUEST_REGISTRATION_INTENT); 296 registrationIntent.setPackage(GSF_PACKAGE); 297 registrationIntent.putExtra(EXTRA_APPLICATION_PENDING_INTENT, 298 PendingIntent.getBroadcast(context, 0, new Intent(), 0); 299 registrationIntent.putExtra(EXTRA_SENDER, senderId); 300 context.startService(registrationIntent); 301 / TODO: if intent not found, notification on need to have GSF 302 303 304 /* 305 * Unregister the application. New messages will be blocked by server. 306 */ 307 public static void unregister(Context context) 308 Intent regIntent = new Intent(REQUEST_UNREGISTRATION_INTENT); 309 regIntent.setPackage(GSF_PACKAGE); 310 regIntent.putExtra(EXTRA_APPLICATION_PENDING_INTENT, PendingIntent.getBroadcast(context, 311 0, new Intent(), 0); 312 context.startService(regIntent); 313 314 315 /* 316 * Return the current registration id. 317 * 318 * If result is empty, the registration has failed. 319 * 320 * return registration id, or empty string if the registration is not complete. 321 */ 322 public static String getRegistrationId(Context context) 323 final SharedPreferences prefs = context.getSharedPreferences( 324 PREFERENCE, 325 Context.MODE_PRIVATE); 326 String registrationId = prefs.getString(dm_registration, ); 327 return registrationId; 328 329 330 public static long getLastRegistrationChange(Context context) 331 final SharedPreferences prefs = context.getSharedPreferences( 332 PREFERENCE, 333 Context.MODE_PRIVATE); 334 return prefs.getLong(LAST_REGISTRATION_CHANGE, 0); 335 336 337 static long getBackoff(Context context) 338 final SharedPreferences prefs = context.getSharedPreferences( 339 PREFERENCE, 340 Context.MODE_PRIVATE); 341 return prefs.getLong(BACKOFF, DEFAULT_BACKOFF); 342 343 344 static void setBackoff(Context context, long backoff) 345 final SharedPreferences prefs = context.getSharedPreferences( 346 PREFERENCE, 347 Context.MODE_PRIVATE); 348 Editor editor = prefs.edit(); 349 editor.putLong(BACKOFF, backoff); 350 mit(); 351 352 353 354 / package 355 static void clearRegistrationId(Context context) 356 final SharedPreferences prefs = context.getSharedPreferences( 357 PREFERENCE, 358 Context.MODE_PRIVATE); 359 Editor editor = prefs.edit(); 360 editor.putString(dm_registration, ); 361 editor.putLong(LAST_REGISTRATION_CHANGE, System.currentTimeMil