起因
android 5.0之前是，Phone进程对外的服务都是通过TelephonyManager来实现的。现在多出来了个TelecomManager来给应用调用电话相关的功能。所以要看看，这个TelecomManager是何方神圣。
使用举例
Dialer中，拨打电话的时候，最后会调用TelecomManager的placeCall函数。
final TelecomManager tm = (TelecomManager)context.getSystemService(Context.TELECOM_SERVICE);
tm.placeCall(intent.getData(), intent.getExtras());
发现是通过getSystemService来获得的。所以看一下是怎么注册到Context里面去的,是在frameworks/base/core/java/android/app/SystemServiceRegistry.java里面:
registerService(Context.TELECOM_SERVICE, TelecomManager.class,
new CachedServiceFetcher<TelecomManager>() {
@Override
public TelecomManager createService(ContextImpl ctx) {
return new TelecomManager(ctx.getOuterContext());
}});
这样，应用通过getSystemService接口就可以方便使用TelecomManager的实例了。回到placeCall这个函数:
public void placeCall(Uri address, Bundle extras) {
ITelecomService service = getTelecomService();
if (service != null) {
if (address == null) {
Log.w(TAG, "Cannot place call to empty address.");
}
try {
service.placeCall(address, extras == null ? new Bundle() : extras,
mContext.getOpPackageName());
} catch (RemoteException e) {
Log.e(TAG, "Error calling ITelecomService#placeCall", e);
}
}
}
发现是调用ITelecomService这个service
private ITelecomService getTelecomService() {
return ITelecomService.Stub.asInterface(ServiceManager.getService(Context.TELECOM_SERVICE));
}
又是通过Context.TELECOM_SERVICE，发现和之前Dialer用统一个关键词来获得service，但是注意，这个两个不同的方式获得，所以对应的service也不一样。
后面这个是通过ServiceManager来找到系统的服务，然后转成对应的服务端引用。说明必然有个地方把这个
ITelecomService加入到ServiceManager中。所以，搜索代码：
在frameworks/base/services/core/java/com/android/server/telecom/TelecomLoaderService.java的内部类TelecomServiceConnection的onServiceConnected中添加
private class TelecomServiceConnection implements ServiceConnection {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
// Normally, we would listen for death here, but since telecom runs in the same process
// as this loader (process="system") thats redundant here.
try {
service.linkToDeath(new IBinder.DeathRecipient() {
@Override
public void binderDied() {
connectToTelecom();
}
}, 0);
SmsApplication.getDefaultMmsApplication(mContext, false);
ServiceManager.addService(Context.TELECOM_SERVICE, service);
....
即，通过bindService连接了某个service，然后把通过binder返回的service添加到ServiceManager中。
在TelecomLoaderService中可以看到，是绑定了TelecomService（packages/services/Telecomm/src/com/android/server/telecom/components/TelecomService.java），看TelecomService的onBind函数
@Override
public IBinder onBind(Intent intent) {
Log.d(this, "onBind");
initializeTelecomSystem(this);
synchronized (getTelecomSystem().getLock()) {
return getTelecomSystem().getTelecomServiceImpl().getBinder();
}
}
当bindService的命令来的时候，做了两件事，一个是初始化TelecomSystem，一个是返回TelecomServiceImpl中的binder实例（实现了ITelecomService的stub端）。
- initializeTelecomSystem里面生成了TelecomSystem对象，在TelecomSystem的构造函数里面，创建了CallsManager/TelecomServiceImpl/CallIntentProcessor/PhoneAccountRegistrar/MissedCallNotifier等重要的telecom实例。
- getTelecomSystem().getTelecomServiceImpl().getBinder():实际就是得到了packages/services/Telecomm/src/com/android/server/telecom/TelecomServiceImpl.java中的mBinderImpl
private final ITelecomService.Stub mBinderImpl = new ITelecomService.Stub() {
@Override
public PhoneAccountHandle getDefaultOutgoingPhoneAccount(String uriScheme,
String callingPackage) {
synchronized (mLock) {
if (!canReadPhoneState(callingPackage, "getDefaultOutgoingPhoneAccount")) {
return null;
}
....
-
即，最后TelecomManager调用TelecomServiceImpl的placeCall函数完成打电话操作。
/**
* @see android.telecom.TelecomManager#placeCall
*/
@Override
public void placeCall(Uri handle, Bundle extras, String callingPackage) {
enforceCallingPackage(callingPackage);
if (!canCallPhone(callingPackage, "placeCall")) {
throw new SecurityException("Package " + callingPackage
+ " is not allowed to place phone calls");
}// Note: we can still get here for the default/system dialer, even if the Phone // permission is turned off. This is because the default/system dialer is always // allowed to attempt to place a call (regardless of permission state), in case // it turns out to be an emergency call. If the permission is denied and the // call is being made to a non-emergency number, the call will be denied later on // by {@link UserCallIntentProcessor}. final boolean hasCallAppOp = mAppOpsManager.noteOp(AppOpsManager.OP_CALL_PHONE, Binder.getCallingUid(), callingPackage) == AppOpsManager.MODE_ALLOWED; final boolean hasCallPermission = mContext.checkCallingPermission(CALL_PHONE) == PackageManager.PERMISSION_GRANTED; synchronized (mLock) { final UserHandle userHandle = Binder.getCallingUserHandle(); long token = Binder.clearCallingIdentity(); try { final Intent intent = new Intent(Intent.ACTION_CALL, handle); intent.putExtras(extras); new UserCallIntentProcessor(mContext, userHandle).processIntent(intent, callingPackage, hasCallAppOp && hasCallPermission); } finally { Binder.restoreCallingIdentity(token); } } }
问题：什么时候完成发生的启动TelecomService的？
回答：系统启动时SystemServer（frameworks/base/services/java/com/android/server/SystemServer.java）会启动TelecomLoaderService。
mSystemServiceManager.startService(TelecomLoaderService.class);
当系统回调onBootPhase的时候，就会调用connectToTelecom函数去启动TelecomService。
@Override
public void onBootPhase(int phase) {
if (phase == PHASE_ACTIVITY_MANAGER_READY) {
registerDefaultAppNotifier();
registerCarrierConfigChangedReceiver();
connectToTelecom();
}
}
感受：
Google为了弄个用户用的TelecomManager居然搞了这么大的一圈。其实，这就是分层的设计理念。不同层次的调用对应不同的方法。
另外，通过分析也知道了CallsManager等相关函数的创建点。总之，收获满满。
