Communication - 02.Call U
App层
从大拇哥Click CallButton开始手机便已明白，主人这是要打电话。当然，你可以选择直接拨号，也可以通过ContactList，或者从通话记录着手。这些都只是UI的设计不同而已，终归都会有一个统一的入口开始Calling。这个汇合点就是：
android:targetActivity="OutgoingCallBroadcaster"
这是一个独立的Activity，你可以设计各种花里胡哨的拨号方式、Activities，而后通过startActivity跨应用访问来开始 OutgoingCallBroadcaster的生命周期。
CallController.placeCall调用PhoneUtils.placeCall之后，便由app层进入到了framework层。
可以看出app层没有什么太复杂的逻辑，重点还是OutgoingCallBroadcaster之前的UI发挥。
Framework层
作为办实事的framework层，CallManager类 需要知道手机使用的是何种制式的网络，从而调用该制式的类的方法。显然，这里有“工厂方法”的影子。而GsmCallTracker类 调用RIL去发送AT。同时也需要监控Calling的各种状态返回给上层。
public interface Phone
public class PhoneProxy extends Handler implements Phone {}；
public abstract class PhoneBase extends Handler implements Phone {} public class GSMPhone extends PhoneBase {}
从上图可以看出，我们的首要目的是让上层用户获得一个XXXPhone。
PhoneApp类 中 onCreate方法 调用PhoneFactory类的静态方法 makeDefaultPhones():
- PhoneFactory
sCommandsInterface = new RIL(context, networkMode, cdmaSubscription);
int phoneType = getPhoneType(networkMode); if (phoneType == RILConstants.GSM_PHONE) { sProxyPhone = new PhoneProxy(new GSMPhone(context, sCommandsInterface, sPhoneNotifier)); Log.i(LOG_TAG, “Creating GSMPhone”); } else if (phoneType == RILConstants.CDMA_PHONE) { sProxyPhone = new PhoneProxy(new CDMAPhone(context, sCommandsInterface, sPhoneNotifier)); Log.i(LOG_TAG, “Creating CDMAPhone”); }
Android的应用程序可以使用 PhoneFactory.getDefaultPhone 来获得Phone对象，从而进行一些调用操作。
phone = PhoneFactory.getDefaultPhone(); //返回的是代理，因为面向对象中多态特性适用于多种制式的phone
这样，上层用户便获得了XXXPhone，但却是个代理。
到此为止，app.mCM.dial()中，直接调用GSMPhone.dial()，而GSMPhone对象将通话能力交给 GsmCallTracker类 管理和维护。
- GsmCallTracker类
GsmCallTracker类在 GSMPhone的构造函数 中创建。
mCM.setPhoneType(Phone.PHONE_TYPE_GSM); mCT = new GsmCallTracker(this); mSST = new GsmServiceStateTracker (this); mSMS = new GsmSMSDispatcher(this); mIccFileHandler = new SIMFileHandler(this); mSIMRecords = new SIMRecords(this); mDataConnection = new GsmDataConnectionTracker (this); mSimCard = new SimCard(this); if (!unitTestMode) { mSimPhoneBookIntManager = new SimPhoneBookInterfaceManager(this); mSimSmsIntManager = new SimSmsInterfaceManager(this); mSubInfo = new PhoneSubInfo(this); } mStkService = StkService.getInstance(mCM, mSIMRecords, mContext, (SIMFileHandler)mIccFileHandler, mSimCard); mCM.registerForAvailable(this, EVENT_RADIO_AVAILABLE, null); mSIMRecords.registerForRecordsLoaded(this, EVENT_SIM_RECORDS_LOADED, null); mCM.registerForOffOrNotAvailable(this, EVENT_RADIO_OFF_OR_NOT_AVAILABLE, null); mCM.registerForOn(this, EVENT_RADIO_ON, null); mCM.setOnUSSD(this, EVENT_USSD, null); mCM.setOnSuppServiceNotification(this, EVENT_SSN, null); mSST.registerForNetworkAttach(this, EVENT_REGISTERED_TO_NETWORK, null);
从Tracker可见其与 Handler消息机制 的相关性，而GSMCallTracker在本质上就是一个Handler，那么Tracker与底层的通信机制，也就是与RIL的前端RILJ(ril java)的communication是关键。GsmCallTracker端注册三个EVENT，从而接收并响应RIL对象发出的三种类型的Handler消息。
//***** Constructors GsmCallTracker (GSMPhone phone) { this.phone = phone; cm = phone.mCM; cm.registerForCallStateChanged(this, EVENT_CALL_STATE_CHANGE, null); cm.registerForOn(this, EVENT_RADIO_AVAILABLE, null); cm.registerForNotAvailable(this, EVENT_RADIO_NOT_AVAILABLE, null); }
handleMessage方法中接收并响应RIL对象发出的 Handler回调消息类型，其中对应以上的三个EVENT：
case EVENT_CALL_STATE_CHANGE: pollCallsWhenSafe(); break; case EVENT_RADIO_AVAILABLE: handleRadioAvailable(); break; case EVENT_RADIO_NOT_AVAILABLE: handleRadioNotAvailable(); break;
发现状态变化，最终都会调用cm.getCurrentCalls方法，向RIL对象查询当前Call List。RIL处理完毕，再次向上层给Tracker发送消息。
handleMessage方法中接收，并调用handlePollCalls，根据Call List当前所有的通话连接完成通话状态的更新。
case EVENT_POLL_CALLS_RESULT: ar = (AsyncResult)msg.obj; if (msg == lastRelevantPoll) { if (DBG_POLL) log( "handle EVENT_POLL_CALL_RESULT: set needsPoll=F"); needsPoll = false; lastRelevantPoll = null; handlePollCalls((AsyncResult)msg.obj); } break;
- 通话管理模型
Modem收到AT指令返回字符串返回值，解析创建 DriverCall对象列表，该列表能够真实反映出Modem无线通信模块中所有通话连接的真实信息！
GsmConnection对象表示一个通话连接，根据DriverCall的一些基本信息创建，并更新。
GsmConnection更新的同时同步调用所属的GsmCall对象，并更新相关信息。
在 GSMCallTracker 中维护着通话列表，顺序记录了正连接上的通话状态。
三路电话，每一路默认最大7个连接：
GsmCall ringingCall = new GsmCall(this); GsmCall foregroundCall = new GsmCall(this); GsmCall backgroundCall = new GsmCall(this);
分为了三个类别进行管理：
RingingCall: INCOMING ,WAITING
ForegourndCall: ACTIVE, DIALING ,ALERTING
BackgroundCall: HOLDING
GSMCallTracker通过GsmConnection与DriverCall之间的比较 从而判断通话连接状况的前后变化，改变通话状态相关信息做出相应调整。
handlePollCalls((AsyncResult)msg.obj) 解析出最新通话连接状况，与上一次connection状态比较。而后更新通话相关信息，主要是CallTracker对象中的state, connections, foregroundCall, backgroundCall, ringingCall对象的更新。
OK， 让我们来继续拨号：
Connection dial (String dialString, int clirMode, UUSInfo uusInfo) throws CallStateException { // note that this triggers call state changed notif clearDisconnected(); if (!canDial()) { throw new CallStateException("cannot dial in current state"); } // The new call must be assigned to the foreground call. // That call must be idle, so place anything that's // there on hold if (foregroundCall.getState() == GsmCall.State.ACTIVE) { // this will probably be done by the radio anyway // but the dial might fail before this happens // and we need to make sure the foreground call is clear // for the newly dialed connection switchWaitingOrHoldingAndActive(); // Fake local state so that // a) foregroundCall is empty for the newly dialed connection // b) hasNonHangupStateChanged remains false in the // next poll, so that we don't clear a failed dialing call fakeHoldForegroundBeforeDial(); } if (foregroundCall.getState() != GsmCall.State.IDLE) { //we should have failed in !canDial() above before we get here throw new CallStateException("cannot dial in current state"); } // Dialing, prepare to create a connection
pendingMO = new GsmConnection(phone.getContext(), dialString, this, foregroundCall); hangupPendingMO = false; if (pendingMO.address == null || pendingMO.address.length() == 0 || pendingMO.address.indexOf(PhoneNumberUtils.WILD) >= 0 ) { // Phone number is invalid pendingMO.cause = Connection.DisconnectCause.INVALID_NUMBER; // handlePollCalls() will notice this call not present // and will mark it as dropped. pollCallsWhenSafe(); } else { // Always unmute when initiating a new call setMute(false); // Dialing... goto RIL JAVA
cm.dial(pendingMO.address, clirMode, uusInfo, obtainCompleteMessage()); } updatePhoneState(); phone.notifyPreciseCallStateChanged(); return pendingMO; }
RILJ层
RILJ层，即为RIL的最上层，也就是JAVA编写的部分，主要用于Handler交互。
public void dial(String address, int clirMode, UUSInfo uusInfo, Message result) {
RILRequest rr = RILRequest.obtain(RIL_REQUEST_DIAL, result); rr.mp.writeString(address); rr.mp.writeInt(clirMode); rr.mp.writeInt(0); // UUS information is absent if (uusInfo == null) { rr.mp.writeInt(0); // UUS information is absent } else { rr.mp.writeInt(1); // UUS information is present rr.mp.writeInt(uusInfo.getType()); rr.mp.writeInt(uusInfo.getDcs()); rr.mp.writeByteArray(uusInfo.getUserData()); } if (RILJ_LOGD) riljLog(rr.serialString() + "> " + requestToString(rr.mRequest)); send(rr); }
主要分为两部分：1.构建RILRequest；2. 把它发出去。
private void send(RILRequest rr) { Message msg; if (mSocket == null) { rr.onError(RADIO_NOT_AVAILABLE, null); rr.release(); return; } msg = mSender.obtainMessage(EVENT_SEND, rr); acquireWakeLock(); msg.sendToTarget(); }
Target就是 class RILSender。
RILJ作为RIL的最前端与framework通过handler交流，与下层则通过socket通信。有点“承前启后”的意思。
@Override public void handleMessage(Message msg) { RILRequest rr = (RILRequest)(msg.obj); RILRequest req = null; switch (msg.what) { case EVENT_SEND: /** * mRequestMessagePending++ already happened for every * EVENT_SEND, thus we must make sure * mRequestMessagePending-- happens once and only once */ boolean alreadySubtracted = false; try { LocalSocket s; s = mSocket; if (s == null) { rr.onError(RADIO_NOT_AVAILABLE, null); rr.release(); if (mRequestMessagesPending > 0) mRequestMessagesPending--; alreadySubtracted = true; return; } synchronized (mRequestsList) { mRequestsList.add(rr); mRequestMessagesWaiting++; } if (mRequestMessagesPending > 0) mRequestMessagesPending--; alreadySubtracted = true; byte[] data; data = rr.mp.marshall(); rr.mp.recycle(); rr.mp = null; if (data.length > RIL_MAX_COMMAND_BYTES) { throw new RuntimeException( "Parcel larger than max bytes allowed! " + data.length); } // parcel length in big endian dataLength[0] = dataLength[1] = 0; dataLength[2] = (byte)((data.length >> 8) & 0xff); dataLength[3] = (byte)((data.length) & 0xff); //Log.v(LOG_TAG, "writing packet: " + data.length + " bytes"); s.getOutputStream().write(dataLength); s.getOutputStream().write(data); }
... ... case EVENT_WAKE_LOCK_TIMEOUT:
最后将数据写入通过LocalSocket连接对象获取输出流。
以上便是Java部分，RIL的重难点在于下面的C部分。简单的阐述，只是针对dial，但对流程的理解多少有点帮助。
Telephony的架构有太多细节可以探究，有志者可以摸索，“自己动脑丰衣足食”，本人摸索完毕后就不再此赘述了。
补充：看到园内一篇介绍开会注意事项的随笔，其中有云：戒条八、不要忘记把会议总结发送给与会人
我这也算是个人的学习总结性随笔，好记性不如烂笔头。
HAPPY WEEKEND:-)
