android 2.2資料連線過程

整個資料連線過程主要靠DataConnection及其對應cdma和gsm的子類

資料連線包含幾種狀態，建構函式裡面必須添加這幾種狀態，並且指定一個初始狀態，如下代碼

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); 

設定初始化狀態為mInactiveState，意思是未啟用的串連

private DcInactiveState mInactiveState = new DcInactiveState();

所有的狀態類都是繼承自HierarchicalState，就像

private class DcInactiveState extends HierarchicalState

狀態之間可以相互轉換，可以接收訊息，進行串連斷開等操作

需要進行串連之時，調用

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

public void connect(Message onCompletedMsg)，前者指定apn設定，後者為null

兩個方法都是向目前狀態發送訊息

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

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

mInactiveState收到訊息之後

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;
調用onConnect(cp)，這是個abstract函數，在GsmDataConnection和CdmaDataConnection裡面得到了實現，在CdmaDataConnection的onConnect(cp)裡面，調用RIL.java裡面的方法：

 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); 

這樣，把請求發送到RIL層之後，轉換到mActivatingState狀態，接下來就是等待RIL層回應了

跟上一篇部落格學習RIL那樣，會形成一個非同步結果，綁定到訊息裡面發上來

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

rr.mResult.sendToTarget();

而上面的mActivationState狀態會收到

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;