一、总体流程
Android的Phone设计的相当复杂，只有了解了Phone的设计框架才能把握电话的拨号或来电流程，这里介绍一下电话的来电流程。
电话流程图：
电话流程
Framework层的RIL中的RILReceiver线程从rild服务进程中读取modem发送上来的来电消息等信息，通过消息注册-响应机制来通知上层处理，上图清晰地显示了各层之间的消息处理关系，CallManager连接Framework层和应用层的Phone，
CallManager处理GSMPhone注册的消息事件，并且触发CallManager注册的消息事件，而CallNotifier处理CallManager消息，这样就将RIL层的消息一级一级传送的应用层的Phone了。
二、RIL层事件注册过程
2.1 构建对应的Phone对象
在PhoneFactory的makeDefaultPhone函数中，首先构造一个DefaultPhoneNotifier对象和RIL对象，然后从数据库中读取网络模式，根据网络模式得到对应的电话类型，从而构造对应的Phone对象，并为该Phone对象创建一个PhoneProxy代理对象。对于GSM网络，会构造一个GSMPhone对象
//frameworks\base\telephony\java\com\android\internal\telephony\PhoneFactory.java
public static void makeDefaultPhone(Context context) {
synchronized(Phone.class) {
if (!sMadeDefaults) {
sLooper = Looper.myLooper();
sContext = context;
if (sLooper == null) {
throw new RuntimeException("PhoneFactory.makeDefaultPhone must be called from Looper thread");
}
int retryCount = 0;
for(;;) {
boolean hasException = false;
retryCount ++;
try {
new LocalServerSocket("com.android.internal.telephony");
} catch (java.io.IOException ex) {
hasException = true;
}
if ( !hasException ) {
break;
} else if (retryCount > SOCKET_OPEN_MAX_RETRY) {
throw new RuntimeException("PhoneFactory probably already running");
} else {
try {
Thread.sleep(SOCKET_OPEN_RETRY_MILLIS);
} catch (InterruptedException er) {
}
}
}
sPhoneNotifier = new DefaultPhoneNotifier();
// Get preferred network mode
int preferredNetworkMode = RILConstants.PREFERRED_NETWORK_MODE;
if (TelephonyManager.getLteOnCdmaModeStatic() == PhoneConstants.LTE_ON_CDMA_TRUE) {
preferredNetworkMode = Phone.NT_MODE_GLOBAL;
}
//从数据库中读取网络模式
int networkMode = Settings.Global.getInt(context.getContentResolver(),
Settings.Global.PREFERRED_NETWORK_MODE, preferredNetworkMode);
Log.i(LOG_TAG, "Network Mode set to " + Integer.toString(networkMode));
int cdmaSubscription;
int lteOnCdma = TelephonyManager.getLteOnCdmaModeStatic();
switch (lteOnCdma) {
case PhoneConstants.LTE_ON_CDMA_FALSE:
cdmaSubscription = CdmaSubscriptionSourceManager.SUBSCRIPTION_FROM_NV;
Log.i(LOG_TAG, "lteOnCdma is 0 use SUBSCRIPTION_FROM_NV");
break;
case PhoneConstants.LTE_ON_CDMA_TRUE:
cdmaSubscription = CdmaSubscriptionSourceManager.SUBSCRIPTION_FROM_RUIM;
Log.i(LOG_TAG, "lteOnCdma is 1 use SUBSCRIPTION_FROM_RUIM");
break;
case PhoneConstants.LTE_ON_CDMA_UNKNOWN:
default:
//Get cdmaSubscription mode from Settings.System
cdmaSubscription = Settings.Global.getInt(context.getContentResolver(),
Settings.Global.PREFERRED_CDMA_SUBSCRIPTION,
preferredCdmaSubscription);
Log.i(LOG_TAG, "lteOnCdma not set, using PREFERRED_CDMA_SUBSCRIPTION");
break;
}
Log.i(LOG_TAG, "Cdma Subscription set to " + cdmaSubscription);
//reads the system properties and makes commandsinterface
sCommandsInterface = new RIL(context, networkMode, cdmaSubscription);
// Instantiate UiccController so that all other classes can just call getInstance()
UiccController.make(context, sCommandsInterface);
//根据网络模式得到电话类型
int phoneType = TelephonyManager.getPhoneType(networkMode);
//根据电话类型创建对应类型的Phone对象，并且使用创建的Phone对象来构造PhoneProxy代理对象
if (phoneType == PhoneConstants.PHONE_TYPE_GSM) {
Log.i(LOG_TAG, "Creating GSMPhone");
sProxyPhone = new PhoneProxy(new GSMPhone(context,sCommandsInterface, sPhoneNotifier));
} else if (phoneType == PhoneConstants.PHONE_TYPE_CDMA) {
switch (TelephonyManager.getLteOnCdmaModeStatic()) {
case PhoneConstants.LTE_ON_CDMA_TRUE:
Log.i(LOG_TAG, "Creating CDMALTEPhone");
sProxyPhone = new PhoneProxy(new CDMALTEPhone(context,sCommandsInterface, sPhoneNotifier));
break;
case PhoneConstants.LTE_ON_CDMA_FALSE:
default:
Log.i(LOG_TAG, "Creating CDMAPhone");
sProxyPhone = new PhoneProxy(new CDMAPhone(context,sCommandsInterface, sPhoneNotifier));
break;
}
}
sMadeDefaults = true;
}
}
}
2.2 构建对象GSMPhone
在构造GSMPhone对象时，首先使用父类的成员变量CommandsInterfac mCM设置电话类型，由于RIL类实现了CommandsInterfac接口，因此mCM引用RIL对象。在构造GSMPhone对象时通过参数传入并设置父类PhoneBase的成员变量mCM。
//frameworks\base\telephony\java\com\android\internal\telephony\gsm\ GSMPhone.java
public GSMPhone (Context context, CommandsInterface ci, PhoneNotifier notifier, boolean unitTestMode) {
super(notifier, context, ci, unitTestMode);
mCM.setPhoneType(Phone.PHONE_TYPE_GSM);
mIccCard.set(MsUiccController.getInstance(this).getIccCard());
mIccRecords = mIccCard.get().getIccRecords();
mCT = new GsmCallTracker(this);
mSST = new GsmServiceStateTracker (this);
mSMS = new GsmSMSDispatcher(this, mSmsStorageMonitor, mSmsUsageMonitor);
if (!unitTestMode) {
mSimPhoneBookIntManager = new SimPhoneBookInterfaceManager(this);
mSimSmsIntManager = new SimSmsInterfaceManager(this, mSMS);
mSubInfo = new PhoneSubInfo(this);
}
mCM.registerForAvailable(this, EVENT_RADIO_AVAILABLE, null);
registerForSimRecordEvents();
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.registerForNetworkAttached(this, EVENT_REGISTERED_TO_NETWORK, null);
mHandlerThread = new HandlerThread("GSMPhone_AsyncThread");
mHandlerThread.start();
mAsyncThread = new AsyncThread(mHandlerThread.getLooper());
if (false) {
try {
//debugSocket = new LocalServerSocket("com.android.internal.telephony.debug");
debugSocket = new ServerSocket();
debugSocket.setReuseAddress(true);
debugSocket.bind (new InetSocketAddress("127.0.0.1", 6666));
debugPortThread
= new Thread(
new Runnable() {
public void run() {
for(;;) {
try {
Socket sock;
sock = debugSocket.accept();
Log.i(LOG_TAG, "New connection; resetting radio");
mCM.resetRadio(null);
sock.close();
} catch (IOException ex) {
Log.w(LOG_TAG,
"Exception accepting socket", ex);
}
}
}
},
"GSMPhone debug");
debugPortThread.start();
} catch (IOException ex) {
Log.w(LOG_TAG, "Failure to open com.android.internal.telephony.debug socket", ex);
}
}
//Change the system property
SystemProperties.set(TelephonyProperties.CURRENT_ACTIVE_PHONE,
new Integer(Phone.PHONE_TYPE_GSM).toString());
}
2.3 父类PhoneBase
构造GSMPhone对象同时也会创建一个GsmCallTracker对象，GSMCallTracker实现了电话的拨打（Dial）、接听/拒绝(accept/reject)、挂断（hangup）、保持（hold）、切换以及电话会议等功能，它还负责查询Modem当前有多少路通话，维护电话状态等功能。GSMCallTracker中包含了GsmConnection、RegistrantList、 GSMCall和Phone.State等类的对象实例。在GSMCallTracker构造函数中向RIL类实例注册了RegistrantList，当通话状态及射频Radio状态变化时，就会通知GSMCallTracker。
//frameworks\base\telephony\java\com\android\internal\telephony\ PhoneBase.java
protected PhoneBase(PhoneNotifier notifier, Context context, CommandsInterface ci,
boolean unitTestMode) {
this.mNotifier = notifier;
this.mContext = context;
mLooper = Looper.myLooper();
mCM = ci;
setPropertiesByCarrier();
setUnitTestMode(unitTestMode);
SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
mDnsCheckDisabled = sp.getBoolean(DNS_SERVER_CHECK_DISABLED_KEY, false);
mCM.setOnCallRing(this, EVENT_CALL_RING, null);
mIsVoiceCapable = mContext.getResources().getBoolean(com.android.internal.R.bool.config_voice_capable);
mDoesRilSendMultipleCallRing = SystemProperties.getBoolean(
TelephonyProperties.PROPERTY_RIL_SENDS_MULTIPLE_CALL_RING, true);
Log.d(LOG_TAG, "mDoesRilSendMultipleCallRing=" + mDoesRilSendMultipleCallRing);
mCallRingDelay = SystemProperties.getInt(
TelephonyProperties.PROPERTY_CALL_RING_DELAY, 3000);
Log.d(LOG_TAG, "mCallRingDelay=" + mCallRingDelay);
// Initialize device storage and outgoing SMS usage monitors for SMSDispatchers.
mSmsStorageMonitor = new SmsStorageMonitor(this);
mSmsUsageMonitor = new SmsUsageMonitor(context);
}
2.4 电话Tracker
cm引用RIL对象，在这里注册了电话状态改变事件，视频电话状态改变事件，无线开关事件等。由于RIL实现了CommandsInterface接口，并继承于BaseCommands抽象类，registerForCallStateChanged函数实现在RIL的父类BaseCommands中
这里为RIL注册了一些消息事件，并指定GsmCallTracker来处理这些消息。
//frameworks\base\telephony\java\com\android\internal\telephony\gsm\ GsmCallTracker.java
GsmCallTracker (GSMPhone phone) {
this.phone = phone;
cm = phone.mCM;
cm.registerForCallStateChanged(this, EVENT_CALL_STATE_CHANGE, null);
cm.registerForVideoCallStateChanged(this, EVENT_CALL_STATE_CHANGE, null);
cm.registerForOn(this, EVENT_RADIO_AVAILABLE, null);
cm.registerForNotAvailable(this, EVENT_RADIO_NOT_AVAILABLE, null);
sendEmptyMessage(EVENT_INITIALIZE);
}
2.5 注册监听状态函数
该函数通过Handler及对应的事件消息来构造一个Registrant对象，并将其注册到mCallStateRegistrants对象中，mCallStateRegistrants为RegistrantList类型变量，定义在RIL的父类BaseCommands中，RegistrantList类是用于保存注册的处理指定消息的所有Handler，RegistrantList类首先将某个消息及处理该消息的Handler封装成Registrant对象，并将该对象保存到成员变量registrants动态数组中。
//frameworks\base\telephony\java\com\android\internal\telephony\BaseCommands.java
public void registerForCallStateChanged(Handler h, int what, Object obj) {
Registrant r = new Registrant (h, what, obj);
mCallStateRegistrants.add(r);
}
2.6 电话流程状态
对于电话状态改变事件，注册的Handle对象为GsmCallTracker，因此在电话状态改变事件到来时，GsmCallTracker将处理EVENT_CALL_STATE_CHANGE消息事件。
GsmCallTracker有三个成员变量：
- GsmCall ringingCall = new GsmCall(this) 前台Call，其中对应的Connection是ACTIVE,DIALING,ALERTING状态的，即激活状态
- GsmCall foregroundCall = new GsmCall(this) 后台Call，其中对应的Connection是HOLDING状态的，即保持状态
- GsmCall backgroundCall = new GsmCall(this) 来电Call，其中对应的Connection是INCOMING,WAITING状态的，即来电状态
三、电话流程函数跟踪
3.1 构建全局对象及注册事件
在Phone进程启动的时，PhoneApp的onCreate函数首先被调用，PhoneApp会构造各种全局对象，同时也会注册一些事件。
mCM = CallManager.getInstance();
mCM.registerPhone(phone);
//function here
public boolean registerPhone(Phone phone) {
Phone basePhone = getPhoneBase(phone);
if (basePhone != null && !mPhones.contains(basePhone)) {
if (DBG) {
Log.d(LOG_TAG, "registerPhone(" +
phone.getPhoneName() + " " + phone + ")");
}
if (mPhones.isEmpty()) {
mDefaultPhone = basePhone;
}
mPhones.add(basePhone);
mRingingCalls.add(basePhone.getRingingCall());
mBackgroundCalls.add(basePhone.getBackgroundCall());
mForegroundCalls.add(basePhone.getForegroundCall());
registerForPhoneStates(basePhone);
return true;
}
return false;
}
private void registerForPhoneStates(Phone phone) {
// for common events supported by all phones
phone.registerForPreciseCallStateChanged(mHandler, EVENT_PRECISE_CALL_STATE_CHANGED, null);
phone.registerForDisconnect(mHandler, EVENT_DISCONNECT, null);
phone.registerForNewRingingConnection(mHandler, EVENT_NEW_RINGING_CONNECTION, null);
phone.registerForUnknownConnection(mHandler, EVENT_UNKNOWN_CONNECTION, null);
phone.registerForIncomingRing(mHandler, EVENT_INCOMING_RING, null);
phone.registerForRingbackTone(mHandler, EVENT_RINGBACK_TONE, null);
phone.registerForInCallVoicePrivacyOn(mHandler, EVENT_IN_CALL_VOICE_PRIVACY_ON, null);
phone.registerForInCallVoicePrivacyOff(mHandler, EVENT_IN_CALL_VOICE_PRIVACY_OFF, null);
phone.registerForDisplayInfo(mHandler, EVENT_DISPLAY_INFO, null);
phone.registerForSignalInfo(mHandler, EVENT_SIGNAL_INFO, null);
phone.registerForResendIncallMute(mHandler, EVENT_RESEND_INCALL_MUTE, null);
phone.registerForMmiInitiate(mHandler, EVENT_MMI_INITIATE, null);
phone.registerForMmiComplete(mHandler, EVENT_MMI_COMPLETE, null);
phone.registerForSuppServiceFailed(mHandler, EVENT_SUPP_SERVICE_FAILED, null);
phone.registerForServiceStateChanged(mHandler, EVENT_SERVICE_STATE_CHANGED, null);
// for events supported only by GSM and CDMA phone
if (phone.getPhoneType() == PhoneConstants.PHONE_TYPE_GSM ||
phone.getPhoneType() == PhoneConstants.PHONE_TYPE_CDMA) {
phone.setOnPostDialCharacter(mHandler, EVENT_POST_DIAL_CHARACTER, null);
}
// for events supported only by CDMA phone
if (phone.getPhoneType() == PhoneConstants.PHONE_TYPE_CDMA ){
phone.registerForCdmaOtaStatusChange(mHandler, EVENT_CDMA_OTA_STATUS_CHANGE, null);
phone.registerForSubscriptionInfoReady(mHandler, EVENT_SUBSCRIPTION_INFO_READY, null);
phone.registerForCallWaiting(mHandler, EVENT_CALL_WAITING, null);
phone.registerForEcmTimerReset(mHandler, EVENT_ECM_TIMER_RESET, null);
}
}
3.2 CallManager层事件注册过程
在启动PhoneApp时，同样也会创建一个CallNotifier对象
notifier = CallNotifier.init(this, phone, ringer, mBtHandsfree, new CallLogAsync());这构造CallNotifier对象过程中，为CallManager层注册了一些消息事件，并指定CallNotifier来处理这些消息
private void registerForNotifications() {
mCM.registerForNewRingingConnection(this, PHONE_NEW_RINGING_CONNECTION, null);
mCM.registerForPreciseCallStateChanged(this, PHONE_STATE_CHANGED, null);
mCM.registerForDisconnect(this, PHONE_DISCONNECT, null);
mCM.registerForUnknownConnection(this, PHONE_UNKNOWN_CONNECTION_APPEARED, null);
mCM.registerForIncomingRing(this, PHONE_INCOMING_RING, null);
mCM.registerForCdmaOtaStatusChange(this, EVENT_OTA_PROVISION_CHANGE, null);
mCM.registerForCallWaiting(this, PHONE_CDMA_CALL_WAITING, null);
mCM.registerForDisplayInfo(this, PHONE_STATE_DISPLAYINFO, null);
mCM.registerForSignalInfo(this, PHONE_STATE_SIGNALINFO, null);
mCM.registerForInCallVoicePrivacyOn(this, PHONE_ENHANCED_VP_ON, null);
mCM.registerForInCallVoicePrivacyOff(this, PHONE_ENHANCED_VP_OFF, null);
mCM.registerForRingbackTone(this, PHONE_RINGBACK_TONE, null);
mCM.registerForResendIncallMute(this, PHONE_RESEND_MUTE, null);
}
3.3 状态变化的介绍：
- 当有PHONE_NEW_RINGING_CONNECTION类型消息到来时，意味着一个RINGING或WAITING的连接（connection）出现，此时handleMessage函数调用onNewRingingConnection来处理。后者先检查Settings里的设置是否可以接听电话；然后进 行响铃（见InCallTonePlayer）和显示InCallScreen的UI，见PhoneUtils.showIncomingCallUi()和PhoneApp.displayCallScreen()两个函数。通话过程中的铃音提示由线程类InCallTonePlayer完成。
- 当有PHONE_INCOMING_RING类型的消息到来时，意味着RIL层受到Ring，此处播放铃音。它使用的是Ringer.ring()函数，它会创建一个线程去播放铃音,见Ringer.makeLooper函数。
- 当有PHONE_STATE_CHANGED消息时，表明Phone的状态发生了改变，比如响铃后接通了电话，此时处理函数是onPhoneStateChanged，比如再次确认停止铃音、更新状态栏列的状态通知等。
- 当有PHONE_DISCONNECT消息时，表明电话连接已挂断或RingCall断掉。其处理函数是onDisconnect。它清理现场诸如音频通道恢复、来电响铃的停止确认、对InCallScreen的UI清理、若有未接电话须在状态栏显示等。
3.4 电话状态改变事件处理
我们已经知道在RIL中分别创建了两个线程，一个用于往rild套接字中写入数据，一个用于从该套接字中读取rild服务进程发送上来的数据。对于来电事件，RILReceiver会读取到rild发送过来的来电信息。
RIL
以下这段代码是RILReceiver线程不断循环读取来自rild的AT Response，
调用processResponse进行处理，根据返回结果中不同的Request号，
调用到相应的responseXXX函数簇，获取AT执行结果。
//frameworks\base\telephony\java\com\android\internal\telephony\RIL.java
try {
InputStream is = mSocket.getInputStream();
for (;;) {
Parcel p;
//从rild套接字中读取消息
length = readRilMessage(is, buffer);
if (length < 0) {
// End-of-stream reached
break;
}
//将读取到的数据序列化到Parcel对象中
p = Parcel.obtain();
p.unmarshall(buffer, 0, length);
p.setDataPosition(0);
//数据处理
processResponse(p);
p.recycle();
}
} catch (java.io.IOException ex) {
Log.i(LOG_TAG, "'" + SOCKET_NAME_RIL + "' socket closed", ex);
} catch (Throwable tr) {
Log.e(LOG_TAG, "Uncaught exception read length=" + length +
"Exception:" + tr.toString());
}
private void processResponse (Parcel p) {
int type;
type = p.readInt();
if (type == RESPONSE_UNSOLICITED) {
processUnsolicited (p);
} else if (type == RESPONSE_SOLICITED) {
processSolicited (p);
}
releaseWakeLockIfDone();
}
在Android之rild进程启动源码分析介绍了，rild服务进程会接收到两种类型的消息，一种是Ap向Bp发送请求，Bp给Ap发送回复消息，一种是Bp主动给Ap发送事件，对于请求响应事件，调用processSolicited函数来处理，而对于BP主动发起的事件则调用processUnsolicited函数来处理。来电属于BP主动发起的请求事件，因此processUnsolicited函数将处理来电请求
protected void processUnsolicited (Parcel p) {
int response;
Object ret;
response = p.readInt();
try {
switch(response) {
case RIL_UNSOL_RESPONSE_CALL_STATE_CHANGED: ret = responseVoid(p); break;
default:
throw new RuntimeException("Unrecognized unsol response: " + response);
}
} catch (Throwable tr) {
Log.e(LOG_TAG, "Exception processing unsol response: " + response +
"Exception:" + tr.toString());
return;
}
switch(response) {
case RIL_UNSOL_RESPONSE_CALL_STATE_CHANGED:
if (RILJ_LOGD) unsljLog(response);
mCallStateRegistrants.notifyRegistrants(new AsyncResult(null, null, null));
break;
}
}
mCallStateRegistrants为RegistrantList类型变量，前面已经介绍了消息注册过程，这里调用RegistrantList的notifyRegistrants函数来通知所有注册过该消息的Handler处理该消息。
//frameworks\base\core\java\android\os\RegistrantList.java
public void notifyRegistrants(){
internalNotifyRegistrants(null, null);
}
private synchronized void internalNotifyRegistrants (Object result, Throwable exception){
for (int i = 0, s = registrants.size(); i < s ; i++) {
Registrant r = (Registrant) registrants.get(i);
r.internalNotifyRegistrant(result, exception);
}
}
这里循环遍历成员变量registrants中保存的所有Registrant对象，前面介绍到，在注册某个Handler处理指定消息时，首先将其封装为Registrant对象，这里取出该消息对应的所有Registrant对象，并调用该对象的internalNotifyRegistrant函数来触发注册的Handler处理该消息。
//frameworks\base\core\java\android\os\Registrant.java
void internalNotifyRegistrant (Object result, Throwable exception){
Handler h = getHandler();
if (h == null) {
clear();
} else {
Message msg = Message.obtain();
msg.what = what;
msg.obj = new AsyncResult(userObj, result, exception);
h.sendMessage(msg);
}
}
该函数其是就是向注册的Handler中发送消息，消息为注册的消息类型。由于在构造GsmCallTracker对象时，已经在BaseCommands中注册了EVENT_CALL_STATE_CHANGE消息的处理Handler为GsmCallTracker对象本身，
cm.registerForCallStateChanged(this, EVENT_CALL_STATE_CHANGE, null);
因此mCallStateRegistrants.notifyRegistrants(new AsyncResult(null, null, null))将向GsmCallTracker对象发送EVENT_CALL_STATE_CHANGE的消息
//frameworks\base\telephony\java\com\android\internal\telephony\CallTracker.java
public void handleMessage (Message msg) {
AsyncResult ar;
switch (msg.what) {
case EVENT_CALL_STATE_CHANGE:
pollCallsWhenSafe();
break;
}
}
函数最终调用pollCallsWhenSafe来处理EVENT_CALL_STATE_CHANGE消息，pollCallsWhenSafe用于查询当前的通话状态。
protected void pollCallsWhenSafe() {
needsPoll = true;
if (checkNoOperationsPending()) {
lastRelevantPoll = obtainMessage(EVENT_POLL_CALLS_RESULT);
cm.getCurrentCalls(lastRelevantPoll);
}
}
函数checkNoOperationsPending就是判断变量pendingOperations是否等于0，如果等于0，则调用CommandsInterface的getCurrentCalls函数来发送一个EVENT_POLL_CALLS_RESULT消息，该函数实现在RIL.java中。
AT命令CLCC查询结果对应于Connection类中的成员变量，一 路电话对应一个对象。
//frameworks\base\telephony\java\com\android\internal\telephony\RIL.java
public void getCurrentCalls (Message result) {
RILRequest rr = RILRequest.obtain(RIL_REQUEST_GET_CURRENT_CALLS, result);
if (RILJ_LOGD) riljLog(rr.serialString() + "> " + requestToString(rr.mRequest));
send(rr);
}
未完~~
文 | 力卉编程
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