WIFI启动流程-NEW

在Android4.0 wifi启动流程一中，就分析到启动wifimonitor线程来接收wpa_supplicant发送的消息，之后切换到SupplicantStartingState状态。

在wifiMonitor.java中wifiMonitor线程的开始就是连接supplicant，程序如下：

public void run() {

 

            if (connectToSupplicant()) {

                // Send a message indicating that it is now possible to send commands

                // to the supplicant

                mStateMachine.sendMessage(SUP_CONNECTION_EVENT);

            } else {

                mStateMachine.sendMessage(SUP_DISCONNECTION_EVENT);

                return;

            }

connectToSupplicant()调用JNI函数WifiNative.connectToSupplicant()，如果连接成功则向wifiStatemachine发送SUP_CONNECTION_EVENT消息。

在wifistateMachine.java中，wifi状态机当前状态是SupplicantStartingState，处理SUP_CONNECTION_EVENT消息，如下：

classSupplicantStartingStateextends State {

        @Override

        public void enter() {

            if (DBG) log(getName() + "\n");

            EventLog.writeEvent(EVENTLOG_WIFI_STATE_CHANGED, getName());

        }

        @Override

        public boolean processMessage(Message message) {

            if (DBG) log(getName() + message.toString() + "\n");

            switch(message.what) {

                case WifiMonitor.SUP_CONNECTION_EVENT:

                    if (DBG) log("Supplicant connection established");

                    setWifiState(WIFI_STATE_ENABLED);

                    mSupplicantRestartCount = 0;

                    /* Reset the supplicant state to indicate the supplicant

                     * state is not known at this time */

                    mSupplicantStateTracker.sendMessage(CMD_RESET_SUPPLICANT_STATE);

                    mWpsStateMachine.sendMessage(CMD_RESET_WPS_STATE);

                    /* Initialize data structures */

                    mLastBssid = null;

                    mLastNetworkId = WifiConfiguration.INVALID_NETWORK_ID;

                    mLastSignalLevel = -1;

 

                    mWifiInfo.setMacAddress(WifiNative.getMacAddressCommand());

 

                    WifiConfigStore.initialize(mContext);

 

                    sendSupplicantConnectionChangedBroadcast(true);

                    transitionTo(mDriverStartedState);

                    break;

1，  setWifiState(WIFI_STATE_ENABLED)：设置wifi状态，通知有关进程wifi的状态。

WifiEnabler接收到该消息时会调用handleWifiStateChanged，如下：

if (WifiManager.WIFI_STATE_CHANGED_ACTION.equals(action)) {

                handleWifiStateChanged(intent.getIntExtra(

                        WifiManager.EXTRA_WIFI_STATE, WifiManager.WIFI_STATE_UNKNOWN));

handleWifiStateChanged定义如下：

private void handleWifiStateChanged(int state) {

        switch (state) {

            case WifiManager.WIFI_STATE_ENABLING:

                mSwitch.setEnabled(false);

                break;

            case WifiManager.WIFI_STATE_ENABLED:

                setSwitchChecked(true);

                mSwitch.setEnabled(true);

                break;

根据此消息WIFI_STATE_ENABLED会把settings里的Switch控件设置成enable状态。

 

WifiSettings接收到WIFI_STATE_CHANGED_ACTION会调用updateWifiState函数，如下：

private void handleEvent(Context context, Intent intent) {

        String action = intent.getAction();

        if (WifiManager.WIFI_STATE_CHANGED_ACTION.equals(action)) {

           updateWifiState(intent.getIntExtra(WifiManager.EXTRA_WIFI_STATE,

                    WifiManager.WIFI_STATE_UNKNOWN));

updateWifiState函数定义如下：

private void updateWifiState(int state) {

        getActivity().invalidateOptionsMenu();

 

        switch (state) {

            case WifiManager.WIFI_STATE_ENABLED:

                mScanner.resume();

                return; // not break, to avoid the call to pause() below

 

            case WifiManager.WIFI_STATE_ENABLING:

                addMessagePreference(R.string.wifi_starting);

                break;

 

            case WifiManager.WIFI_STATE_DISABLED:

                addMessagePreference(R.string.wifi_empty_list_wifi_off);

                break;

        }

 

        mLastInfo = null;

        mLastState = null;

        mScanner.pause();

}

根据WIFI_STATE_ENABLED消息会调用mScanner.resume()函数，该函数会发送一个空消息，如下：

void resume() {

            if (!hasMessages(0)) {

                sendEmptyMessage(0);

            }

        }

之后handleMessage会调用mWifiManager.startScanActive函数进行ap扫描。

public void handleMessage(Message message) {

            if (mWifiManager.startScanActive()) {

在WifiManager.java中：

public boolean startScanActive() {

        try {

           mService.startScan(true);

            return true;

        } catch (RemoteException e) {

            return false;

        }

    }

这里调用了mService.startScan(true)函数，在wifiService.java中：

public void startScan(boolean forceActive) {

        enforceChangePermission();

       mWifiStateMachine.startScan(forceActive);

    }

这里调用了mWifiStateMachine.startScan(forceActive)，在WifiStateMachine.java中：

public void startScan(boolean forceActive) {

        sendMessage(obtainMessage(CMD_START_SCAN,forceActive?

                SCAN_ACTIVE : SCAN_PASSIVE, 0));

    }

由于forceActive为true，则有发送了一个消息。

2，  mSupplicantStateTracker.sendMessage(CMD_RESET_SUPPLICANT_STATE)：resetsupplicant。

3，  mWifiInfo.setMacAddress(WifiNative.getMacAddressCommand())：回去mac地址赋给wifiinfo类。

4，  transitionTo(mDriverStartedState)：切换到DriverStartedState状态。

 

在DriverStartedState状态接收到CMD_START_SCAN命令进行处理：

case CMD_START_SCAN:

                    eventLoggingEnabled = false;

                    WifiNative.scanCommand(message.arg1 == SCAN_ACTIVE);

                    mScanResultIsPending = true;

                    break;

调用JNI函数WifiNative.scanCommand进行ap扫描。

当扫描完成时，wifiMonitor线程会接收到SCAN_RESULTS事件，然后发送消息：

case SCAN_RESULTS:

                    mStateMachine.sendMessage(SCAN_RESULTS_EVENT);

                    break;