android 2.2数据连接过程

整个数据连接过程主要靠DataConnection及其对应cdma和gsm的子类

数据连接包含几种状态，构造函数里面必须添加这几种状态，并且指定一个初始状态，如下代码

293         addState(mDefaultState);
294             addState(mInactiveState, mDefaultState);
295             addState(mActivatingState, mDefaultState);
296             addState(mActiveState, mDefaultState);
297             addState(mDisconnectingState, mDefaultState);
298             addState(mDisconnectingBadDnsState, mDefaultState);
299         setInitialState(mInactiveState);

设置初始化状态为mInactiveState，意思是未激活的连接

private DcInactiveState mInactiveState = new DcInactiveState();

所有的状态类都是继承自HierarchicalState，就像

private class DcInactiveState extends HierarchicalState

状态之间可以相互转换，可以接收消息，进行连接断开等操作

需要进行连接之时，调用

public void connect(Message onCompletedMsg, ApnSetting apn)；或者

public void connect(Message onCompletedMsg)，前者指定apn设置，后者为null

两个方法都是向当前状态发送消息

sendMessage(obtainMessage(EVENT_CONNECT, new ConnectionParams(apn, onCompletedMsg)));或者

sendMessage(obtainMessage(EVENT_CONNECT, new ConnectionParams(null, onCompletedMsg)));

mInactiveState收到消息之后

554                 case EVENT_CONNECT:
555                     if (DBG) log("DcInactiveState msg.what=EVENT_CONNECT");
556                     ConnectionParams cp = (ConnectionParams) msg.obj;
557                     cp.tag = mTag;
558                     onConnect(cp);
559                     transitionTo(mActivatingState);
560                     retVal = true;
561                     break;
调用onConnect(cp)，这是个abstract函数，在GsmDataConnection和CdmaDataConnection里面得到了实现，在CdmaDataConnection的onConnect(cp)里面，调用RIL.java里面的方法：

98 Message msg = obtainMessage(EVENT_SETUP_DATA_CONNECTION_DONE, cp);
99 msg.obj = cp;

101         phone.mCM.setupDataCall(Integer.toString(RILConstants.SETUP_DATA_TECH_CDMA),
102                 Integer.toString(dataProfile), cp.apn.apn, cp.apn.user,
103                 cp.apn.password, Integer.toString(RILConstants.SETUP_DATA_AUTH_PAP_CHAP), msg);

这样，把请求发送到RIL层之后，转换到mActivatingState状态，接下来就是等待RIL层回应了

跟上一篇博客学习RIL那样，会形成一个异步结果，绑定到消息里面发上来

AsyncResult.forMessage(rr.mResult, ret, null);

rr.mResult.sendToTarget();

而上面的mActivationState状态会收到

589                 case EVENT_SETUP_DATA_CONNECTION_DONE:
590                     if (DBG) log("DcActivatingState msg.what=EVENT_SETUP_DATA_CONNECTION_DONE");
591
592                     ar = (AsyncResult) msg.obj;
593                     cp = (ConnectionParams) ar.userObj;
594
595                     SetupResult result = onSetupConnectionCompleted(ar);
596                     switch (result) {
597                         case SUCCESS:
598                             // All is well
599                             mActiveState.setEnterNotificationParams(cp, FailCause.NONE);
600                             transitionTo(mActiveState);
601                             break;
602                         case ERR_BadCommand:
603                             // Vendor ril rejected the command and didn't connect.
604                             // Transition to inactive but send notifications after
605                             // we've entered the mInactive state.
606                             mInactiveState.setEnterNotificationParams(cp, result.mFailCause);
607                             transitionTo(mInactiveState);
608                             break;
609                         case ERR_BadDns:
610                             // Connection succeeded but DNS info is bad so disconnect
611                             EventLog.writeEvent(EventLogTags.PDP_BAD_DNS_ADDRESS, dnsServers[0]);
612                             tearDownData(cp);
613                             transitionTo(mDisconnectingBadDnsState);
614                             break;
615                         case ERR_Other:
616                             // Request the failure cause and process in this state
617                             phone.mCM.getLastDataCallFailCause(
618                                     obtainMessage(EVENT_GET_LAST_FAIL_DONE, cp));
619                             break;
620                         case ERR_Stale:
621                             // Request is stale, ignore.
622                             break;
623                         default:
624                             throw new RuntimeException("Unkown SetupResult, should not happen");
625                     }
626                     retVal = true;
627                     break;

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