彩信APN切换流程（framework）
TransactionService之前的流程比较简单不在赘述，现在主要理清下从TransactionService到framework的流程。
首先会走到TransactionService的onStartCommand，在此函数中会对当前网络状态进行判断，然后调用到launchTransaction，如果此时网络不可用，会弹出toast，否则就向自己的handler发送EVENT_TRANSACTION_REQUEST。
Handler收到EVENT_TRANSACTION_REQUEST消息后，根据不同的transactionType对data进行不同的处理，我们用的是SEND_TRANSACTION，所以创建了transaction = newSendTransaction，紧接着调用processTransaction，开始进行transaction。
这里就到了关键的函数----beginMmsConnectivity，会根据此函数的返回值来进行下一步的操作，如果是APN_REQUEST_STARTED，则会把当前的MMS放到等待队列里，直到对应的APNready之后才会发送。
beginMmsConnectivity 会调到connectivityservice的startUsingNetworkFeature，下面重点看下这个函数。
public intstartUsingNetworkFeature(int networkType, Stringfeature, // networkType这里我们是0，也就是TYPE_MOBILE，feature 是 enablemms1
IBinderbinder) {
…….
if(networkType == ConnectivityManager.TYPE_MOBILE) {
//if type is MMS,continue setup data call
Slog.d(TAG, "if type is MMS,continue setup data call");
if (!getMobileDataEnabledByPhoneId(getPhoneIdByFeature(feature)) &&
!(feature.indexOf(Phone.FEATURE_ENABLE_MMS)!=-1)) {
//if (!getMobileDataEnabledByPhoneId(getPhoneIdByFeature(feature))) {
if (DBG) Slog.d(TAG, "requested special network with data disabled - rejected");
return Phone.APN_TYPE_NOT_AVAILABLE;
} if (TextUtils.equals(feature, Phone.FEATURE_ENABLE_DM)) {
usedNetworkType = ConnectivityManager.TYPE_MOBILE_DM;
} else if (TextUtils.equals(feature.substring(0,Phone.FEATURE_ENABLE_MMS.length()), Phone.FEATURE_ENABLE_MMS)){ //这里判断feature的前几位是不是enablemms
skipAvailableCheck = true;
usedNetworkType =ConnectivityManager.getMmsTypeByPhoneId(getPhoneIdByFeature(feature));// 将usedNetworkType赋值为11，即TYPE_MOBILE_DM+1
/* yuqing :if send sms with sim2 ,usedNetworkType=TYPE_MOBILE_DM+1=11 */
} else if (TextUtils.equals(feature, Phone.FEATURE_ENABLE_SUPL)) {
usedNetworkType = ConnectivityManager.TYPE_MOBILE_SUPL;
} else if (TextUtils.equals(feature, Phone.FEATURE_ENABLE_DUN)) {
usedNetworkType = ConnectivityManager.TYPE_MOBILE_DUN;
} else if (TextUtils.equals(feature, Phone.FEATURE_ENABLE_HIPRI)) {
usedNetworkType = ConnectivityManager.TYPE_MOBILE_HIPRI;
}
}
NetworkStateTracker network = mNetTrackers[usedNetworkType]; //根据usedNetworkType来选取对应的NetworkStateTracker
if(DBG) Slog.d(TAG, "network = " + network);
if (network != null) {
if (usedNetworkType != networkType){ //传入的是0，现在NetworkStateTracker是11
Integer currentPid = new Integer(getCallingPid());
NetworkStateTracker radio = mNetTrackers[networkType];
NetworkInfo ni = network.getNetworkInfo();
// TODO: using serviceState to check is better for Msms
if (!skipAvailableCheck && ni.isAvailable() == false) {
if (DBG) Slog.d(TAG, "special network not available");
return Phone.APN_TYPE_NOT_AVAILABLE;
} synchronized(this) {
mFeatureUsers.add(f);
if (!mNetRequestersPids[usedNetworkType].contains(currentPid)) {
// this gets used for per-pid dns whenconnected
mNetRequestersPids[usedNetworkType].add(currentPid);
}
}
mHandler.sendMessageDelayed(mHandler.obtainMessage(EVENT_RESTORE_DEFAULT_NETWORK,
f), getRestoreDefaultNetworkDelay());
if (DBG) Slog.d(TAG,"ni.isConnectedOrConnecting()="+ni.isConnectedOrConnecting()); //当卡2的数据连接还没起来的时候，这里是disconnect
if ((ni.isConnectedOrConnecting() == true) &&
!network.isTeardownRequested()) {
if (ni.isConnected() == true) {
// add the pid-specific dns
handleDnsConfigurationChange(networkType);
if (DBG) Slog.d(TAG, "special network already active");
return Phone.APN_ALREADY_ACTIVE;
}
if (DBG) Slog.d(TAG, "special network already connecting");
return Phone.APN_REQUEST_STARTED;
}
// check if the radio in play can make another contact
// assume if cannot fornow if (!isAlreadyConnecting) {
if (DBG) Slog.d(TAG, "reconnecting to special network");
if(!network.reconnect()){ // 重要函数，实际调用的是MobileDataStateTracker.reconnect()，下面分析
//if the mms apn is not available, remove the request from mMmsFeatureRequest
//if not remove it, the othe mms send request will be pending.
if (isMmsFeature(feature) && mMmsFeatureRequest.size() > 0) {
mMmsFeatureRequest.remove(0);
}
return Phone.APN_TYPE_NOT_AVAILABLE;
}
} else {
if (DBG) Slog.d(TAG, "already reconnecting to special network");
}
return Phone.APN_REQUEST_STARTED;
} else{ synchronized(this) {
mFeatureUsers.add(f);
}
mHandler.sendMessageDelayed(mHandler.obtainMessage(EVENT_RESTORE_DEFAULT_NETWORK,
f), getRestoreDefaultNetworkDelay());
return network.startUsingNetworkFeature(feature,
getCallingPid(), getCallingUid());
}
}
return Phone.APN_TYPE_NOT_AVAILABLE;
}
MobileDataStateTracker.reconnect()中会调用setEnableApn (mApnType,true)，此时的apntype是已经转换好了的， mApnType =networkTypeToApnType(netType);
代码如下，我们在创建的时候，选择的是第11个即mNetTrackers[usedNetworkType]，也就是说netype =11，但是经过这个函数转换后神奇的变成了MMS，不知是何用意，暂且先不管。
public static StringnetworkTypeToApnType(int netType) {
switch(netType) {
case ConnectivityManager.TYPE_MOBILE:
return Phone.APN_TYPE_DEFAULT; // TODO - use just one of these
case ConnectivityManager.TYPE_MOBILE_MMS:
return Phone.APN_TYPE_MMS;
case ConnectivityManager.TYPE_MOBILE_SUPL:
return Phone.APN_TYPE_SUPL;
case ConnectivityManager.TYPE_MOBILE_DUN:
return Phone.APN_TYPE_DUN;
case ConnectivityManager.TYPE_MOBILE_HIPRI:
return Phone.APN_TYPE_HIPRI;
case ConnectivityManager.TYPE_MOBILE_DM:
return Phone.APN_TYPE_DM;
default:
// Msms MMS netType @zha
if (ConnectivityManager.isNetworkTypeValid(netType)) {
return Phone.APN_TYPE_MMS;
} else {
Log.e(TAG, "Error mapping networkType " + netType + " toapnType.");
return null;
}
}
}
setEnableApn调用了mPhoneService.enableApnType(apnType)，即DataConnectionTracker.enableApnType,返回值就是此函数中给出的，此函数中又调用了apnTypeToId来转换ID，
转换为APN_MMS_ID，紧接着调用setEnabled，发送EVENT_ENABLE_NEW_APN给自己的handler，回调到onEnableApn--àonEnableNewApn()
调用GsmDataConnectionTracker的onEnableNewApn，这里会调用 cleanUpConnection(true, Phone.REASON_APN_SWITCHED);disconnect当前APN，
停止netstate的poll，也就是为什么我们看到E的图标没有了。
调用MsmsGsmDataConnectionTracker的enableApnType，到MsmsGsmDataConnectionTrackerProxy.onEnableNewApn,此函数就是最终gprsattach的地方。
public staticvoid onEnableNewApn(int phoneId) {
synchronized (sInstance) {
log("onEnableNewApn(" + phoneId + ") activePhoneId:" +sActivePhoneId);
if (phoneId == INVALID_PHONE_ID){ //传入PHONEID不正确
log("phoneId is invalid,onEnableNewApn out!!!");
return;
}
sRequestConnectPhoneId = phoneId;
sRequestPhoneIdBeforeVoiceCallEnd = sRequestConnectPhoneId;
if (sActivePhoneId != INVALID_PHONE_ID) {
if(sRequestConnectPhoneId!=sActivePhoneId){ //当前APN存在，且phoneid和请求值不等，即双卡之间切换时
if(sTracker[sActivePhoneId].isAllPdpDisconnectDone()) { //PDP连接全部断开时，switchphone E图标消失，否则强制断开连接。
checkAndSwitchPhone(sActivePhoneId, null);
} else {
sTracker[sActivePhoneId].cleanupConnections(true,
Phone.REASON_DATA_DISABLED);
}
}else{
sTracker[sActivePhoneId].onEnableNewApnInternal();
}
} else { //当前activephone不存在，
if(sTracker[sRequestConnectPhoneId].getCurrentGprsState() ==ServiceState.STATE_IN_SERVICE) { //如果GPRS inservice，发起数据连接
sTracker[sRequestConnectPhoneId].trySetupData(Phone.REASON_APN_SWITCHED);
sActivePhoneId = sRequestConnectPhoneId;
} else {
sTracker[sRequestConnectPhoneId].mGsmPhone.mCM.setGprsAttach(null);//notinservice ，则发起gprsattach
sActivePhoneId = sRequestConnectPhoneId;
}
}
if(phoneId == sActivePhoneId){ //如果传入值和当前active值相同
// do not need to switch phone, so we initialize sRequestConnectPhoneId.
sRequestConnectPhoneId=INVALID_PHONE_ID;
}
log("onEnableNewApn out");
}
}
如果这次setapnenable没有成功（返回APN_REQUEST_STARTED），TransactionService会将当前的Transaction放入pending列表，
并侦听EVENT_DATA_STATE_CHANGED事件，在合适的时候重新发起，调用processPendingTransaction处理pending的Transaction。