分析Connection的创建

MO的时候，CallIntentProcessor(packages/services/Telecomm/src/com/android/server/telecom/CallIntentProcessor.java)收到去电请求后，会调用CallsManager的startOutgoingCall生成一个Call对象，在其中会走前一篇（绑定InCallService）的逻辑，然后继续往下走，最终到CallsManager.placeOutgoingCall函数，里面通过call.startCreateConnection来创建Connection。最后走到ConnectionServiceWrapper.createConnection()从此走上ConnectionService相关之路。

首先是通过ConnectionServiceWrapper来获得ConnectionService(frameworks/base/telecomm/java/android/telecom/ConnectionService.java),也就是在ConnectionServiceWrapper中通过bindService来和ConnectionService相连。事件上TelephonyConnectionService(packages/services/Telephony/src/com/android/services/telephony/TelephonyConnectionService.java)继承ConnectionService，最后连的是TelephonyConnectionService。
并且，和InCallService类似，连接成功后，设置IConnectionServiceAdapter.Stub的一个adapter到ConnectionService，以完成双向调用。

 mServiceInterface.addConnectionServiceAdapter(adapter)

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

创建connection之前，把ConnectionServiceWrapper对象设置到Call对象中，这样，当有相关操作的时候(比如answer),会调用ConnectionServiceWrapper对象，最终会调用ConnectionService来传到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，里面根据是MO/MT调用了onCreateOutgoingConnection/onCreateInComingConnection,这里我们看onCreateOutgoingConnection，在这个里面创建最终的connection，并调用phone.dial()拨号，把命令发到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相关联。

  connection.setOriginalConnection(originalConnection);

这样，当底层有电话状态变化的时候，会传到connection中，然后再传到call，最后到UI。