Android framework层GSM短信接收流程

  在底层（native层）接收到短信后通过socket发送RIL_UNSOL_RESPONSE_NEW_SMS 响应给RIL。
        在RIL(见com/android/internal/telephony/RIL.java)中，启动RILReceiver用于接收处理底层发送的响应，
                mReceiver= new RILReceiver();
            mReceiverThread= new Thread(mReceiver, "RILReceiver");
           mReceiverThread.start();
        在RILReceiver中通过socket接收来自native层的响应（Parcel对象）：
 
        建立cocket连接
                LocalSockets = null;
               LocalSocketAddress l;
                s= new LocalSocket();
                l= new LocalSocketAddress(SOCKET_NAME_RIL,
                        LocalSocketAddress.Namespace.RESERVED);
               s.connect(l);
 
        读取响应：
                intlength = 0;
 
                InputStreamis = mSocket.getInputStream();
 
                for(;;) {
                       Parcel p;
 
                       length = readRilMessage(is, buffer);
 
                        if(length < 0) {
                           // End-of-stream reached
                           break;
                        }
 
                        p= Parcel.obtain();
                       p.unmarshall(buffer, 0, length);
                       p.setDataPosition(0);
 
                                //处理响应
                       processResponse(p);
                       p.recycle();
                }
 
                在processResponse处理的响应中分为请求响应与非请求响应，其中接收短信为非请求响应。在RIL中处理的响应很多，这里只讨论对于RIL_UNSOL_RESPONSE_NEW_SMS的响应。在收到RIL_UNSOL_RESPONSE_NEW_SMS响应后processResponse调用responseString方法取得响应消息的内容，使用SmsMessage.newFromCMT方法将内容转化为短消息。使用mGsmSmsRegistrant.notifyRegistrant(newAsyncResult(null, sms, null))方法调用短消息的分发类对短消息进行分发(见android/os/Registrant.java)。
 
                对于mGsmSmsRegistrant.notifyRegistrant短信的分发过程：
                在Registrant中notifyRegistrant(AsyncResultar)方法就是向对应的Handler对象发送消息。
            publicvoid
   notifyRegistrant(AsyncResult ar)
    {
       internalNotifyRegistrant (ar.result,ar.exception);
    }
 
    /*package*/void
    internalNotifyRegistrant(Object result, Throwable exception)
    {
        Handlerh = getHandler();
 
        if(h == null) {
            clear();
        }else {
            Messagemsg = Message.obtain();
 
            msg.what= what;
 
            msg.obj= new AsyncResult(userObj, result, exception);
 
           h.sendMessage(msg);
        }
    }
 
        而mGsmSmsRegistrant中的Handler对象即时通过RIL的父类中的setOnNewGsmSms方法设置。
        在phoneFactory的makeDefaultPhone方法中首先创建RIL实例，然后根据网络模式选择创建GSMPhone或是CDMAPhone。在创建GSMPhone时PhoneBaseSMSDispatcher调用了setOnNewGsmSms方法。
                        sCommandsInterface= new RIL(context, networkMode, cdmaSubscription);
 
                intphoneType = getPhoneType(networkMode);
                if(phoneType == Phone.PHONE_TYPE_GSM) {
                   sProxyPhone = new PhoneProxy(newGSMPhone(context,
                           sCommandsInterface,sPhoneNotifier));
                }
 
在 GSMPhone类中：
        public
    GSMPhone(Context context, CommandsInterface ci, PhoneNotifier notifier,boolean unitTestMode) {
        mSMS= new GsmSMSDispatcher(this, mSmsStorageMonitor, mSmsUsageMonitor);
}
 
在 GsmSMSDispatcher中：
        publicGsmSMSDispatcher(PhoneBase phone, SmsStorageMonitor storageMonitor,
            SmsUsageMonitorusageMonitor) {
 
        super(phone,storageMonitor, usageMonitor);
        Log.v("smstest","GsmSMSDispatcher");
        mDataDownloadHandler= new UsimDataDownloadHandler(mCm);
       mCm.setOnNewGsmSms(this,EVENT_NEW_SMS, null);
       mCm.setOnSmsStatus(this,EVENT_NEW_SMS_STATUS_REPORT, null);
       mCm.setOnNewGsmBroadcastSms(this,EVENT_NEW_BROADCAST_SMS, null);
    }
 
其中：mCm就是phoneFactory的makeDefaultPhone方法中创建的sCommandsInterface的引用。
 
此时，native层中的短信已经传递到了GsmSMSDispatcher中，系统调用handleMessage处理mGsmSmsRegistrant.notifyRegistrant发送的message。
        Handlemessage→ SMSDispatcher.handleMessage → GsmSMSDispatcher.dispatchMessage→ SMSDispatcher.dispatchNormalMessage →SMSDispatcher.dispatchPdus
 
最后dispatchPdus通过“android.provider.Telephony.SMS_RECEIVED”广播将短信息传递给各个感兴趣的app
        protectedvoid dispatchPdus(byte[][] pdus) {
        Intentintent = new Intent(Intents.SMS_RECEIVED_ACTION);
       intent.putExtra("pdus",pdus);
       intent.putExtra("format",getFormat());
        dispatch(intent,RECEIVE_SMS_PERMISSION);
    }
 
自此，一条普通短信从native层传递到了app层。

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