分析Connection的創建

MO的時候，CallIntentProcessor(packages/services/Telecomm/src/com/android/server/telecom/CallIntentProcessor.java)收到去電請求后，會調用CallsManager的startOutgoingCall生成一個Call對象，在其中會走前一篇（綁定InCallService）的邏輯，然后繼續往下走，最終到CallsManager.placeOutgoingCall函數，里面通過call.startCreateConnection來創建Connection。最后走到ConnectionServiceWrapper.createConnection()從此走上ConnectionService相關之路。

首先是通過ConnectionServiceWrapper來獲得ConnectionService(frameworks/base/telecomm/java/android/telecom/ConnectionService.java),也就是在ConnectionServiceWrapper中通過bindService來和ConnectionService相連。事件上TelephonyConnectionService(packages/services/Telephony/src/com/android/services/telephony/TelephonyConnectionService.java)繼承ConnectionService，最后連的是TelephonyConnectionService。
并且，和InCallService類似，連接成功后，設置IConnectionServiceAdapter.Stub的一個adapter到ConnectionService，以完成雙向調用。

 mServiceInterface.addConnectionServiceAdapter(adapter)

最后存在了ConnectionServiceAdapter(frameworks/base/telecomm/java/android/telecom/ConnectionServiceAdapter.java)對象中。

創建connection之前，把ConnectionServiceWrapper對象設置到Call對象中，這樣，當有相關操作的時候(比如answer),會調用ConnectionServiceWrapper對象，最終會調用ConnectionService來傳到framework下面去。

    if (mResponse != null && attempt != null) {
        Log.i(this, "Trying attempt %s", attempt);
        PhoneAccountHandle phoneAccount = attempt.connectionManagerPhoneAccount;
        ConnectionServiceWrapper service =
                mRepository.getService(
                        phoneAccount.getComponentName(),
                        phoneAccount.getUserHandle());
        if (service == null) {
            Log.i(this, "Found no connection service for attempt %s", attempt);
            attemptNextPhoneAccount();
        } else {
            mCall.setConnectionManagerPhoneAccount(attempt.connectionManagerPhoneAccount);
            mCall.setTargetPhoneAccount(attempt.targetPhoneAccount);
            mCall.setConnectionService(service);
            setTimeoutIfNeeded(service, attempt);

            service.createConnection(mCall, new Response(service));
        }
    }

走了一圈，最后到了ConnectionService.createConnection，里面根據是MO/MT調用了onCreateOutgoingConnection/onCreateInComingConnection,這里我們看onCreateOutgoingConnection，在這個里面創建最終的connection，并調用phone.dial()撥號，把命令發到RIL。

    com.android.internal.telephony.Connection originalConnection;
    try {
        if (isAddParticipant) {
            phone.addParticipant(number);
            return;
        } else {
            originalConnection = phone.dial(number, null, request.getVideoState(), bundle);
        }
    } catch (CallStateException e) {

然后把dial生成的connection和service包里面的connection相關聯。

  connection.setOriginalConnection(originalConnection);

這樣，當底層有電話狀態變化的時候，會傳到connection中，然后再傳到call，最后到UI。