从AndroidO到AndroidP，Wifi架构上还是发生了挺多变化的。接口上也在发生变化，所以网上的很多的流程梳理已经跟当前的代码逻辑有一些差异了。不过还好，总体上，只要懂了一个版本的代码，看其他版本问题已经不是很大。

梳理还是简单易懂为要务。

调用WifiManager中的setWifiEabled()开启wifi：

public boolean setWifiEnabled(boolean enabled) {

try {

return mService.setWifiEnabled(getContext().getOpPackageName(), enabled);

} catch (RemoteException e) {

throw e.rethrowFromSystemServer();

}

}

通过aidl调用到系统进程中的服务类WifiServiceImpl.java中：

public synchronized boolean setWifiEnabled(String packageName, boolean enable)

throws RemoteException {

enforceChangePermission();

Slog.d(TAG, "setWifiEnabled: " + enable + " pid=" + Binder.getCallingPid()

+ ", uid=" + Binder.getCallingUid() + ", package=" + packageName);

mLog.info("setWifiEnabled package=% uid=% enable=%").c(packageName)

.c(Binder.getCallingUid()).c(enable).flush();

boolean isFromSettings = checkNetworkSettingsPermission(

Binder.getCallingPid(), Binder.getCallingUid());

// If Airplane mode is enabled, only Settings is allowed to toggle Wifi

if (mSettingsStore.isAirplaneModeOn() && !isFromSettings) {

mLog.info("setWifiEnabled in Airplane mode: only Settings can enable wifi").flush();

return false;

}

// If SoftAp is enabled, only Settings is allowed to toggle wifi

boolean apEnabled =

mWifiStateMachine.syncGetWifiApState() != WifiManager.WIFI_AP_STATE_DISABLED;

if (apEnabled && !isFromSettings) {

mLog.info("setWifiEnabled SoftAp not disabled: only Settings can enable wifi").flush();

return false;

}

/*

* Caller might not have WRITE_SECURE_SETTINGS,

* only CHANGE_WIFI_STATE is enforced

*/

long ident = Binder.clearCallingIdentity();

try {

if (! mSettingsStore.handleWifiToggled(enable)) {

// Nothing to do if wifi cannot be toggled

return true;

}

} finally {

Binder.restoreCallingIdentity(ident);

}

if (mPermissionReviewRequired) {

final int wiFiEnabledState = getWifiEnabledState();

if (enable) {

if (wiFiEnabledState == WifiManager.WIFI_STATE_DISABLING

|| wiFiEnabledState == WifiManager.WIFI_STATE_DISABLED) {

if (startConsentUi(packageName, Binder.getCallingUid(),

WifiManager.ACTION_REQUEST_ENABLE)) {

return true;

}

}

} else if (wiFiEnabledState == WifiManager.WIFI_STATE_ENABLING

|| wiFiEnabledState == WifiManager.WIFI_STATE_ENABLED) {

if (startConsentUi(packageName, Binder.getCallingUid(),

WifiManager.ACTION_REQUEST_DISABLE)) {

return true;

}

}

}

mWifiController.sendMessage(CMD_WIFI_TOGGLED);

return true;

}

此段代码逻辑中有涉及到权限检测，以及wifi开关状态保存等操作，最终调用到了如下方法：

mWifiController.sendMessage(CMD_WIFI_TOGGLED);

WifiController是一个状态机，接收到消息会根据处理逻辑进行不同状态的跳转，如下代码

if (checkScanOnlyModeAvailable()) {

setInitialState(mStaDisabledWithScanState);

} else {

setInitialState(mStaDisabledState);

}

WifiController的初始状态为mStaDisabledState，所以CMD_WIFI_TOGGLED消息应该在此状态下处理，查看其处理逻辑：

case CMD_WIFI_TOGGLED:

if (mSettingsStore.isWifiToggleEnabled()) {

if (doDeferEnable(msg)) {

if (mHaveDeferredEnable) {

// have 2 toggles now, inc serial number and ignore both

mDeferredEnableSerialNumber++;

}

mHaveDeferredEnable = !mHaveDeferredEnable;

break;

}

transitionTo(mDeviceActiveState);

} else if (checkScanOnlyModeAvailable()) {

// only go to scan mode if we aren't in airplane mode

if (mSettingsStore.isAirplaneModeOn()) {

transitionTo(mStaDisabledWithScanState);

}

}

break;

代码逻辑大致为：

先判断当前设备状态是否支持打开wifi，如下方法：

public synchronized boolean isWifiToggleEnabled() {

if (!mCheckSavedStateAtBoot) {

mCheckSavedStateAtBoot = true;

if (testAndClearWifiSavedState()) return true;

}

if (mAirplaneModeOn) {

return mPersistWifiState == WIFI_ENABLED_AIRPLANE_OVERRIDE;

} else {

return mPersistWifiState != WIFI_DISABLED;

}

}

有涉及到飞行模式的相关考虑。

检测是否两次点击调用开启wifi是否时间差太短，如果太短，消息延时处理，否则的话直接跳转到mDeviceActiveState

如果wifi当前不支持打开，而此时“wifi scan always开关”打开，我们仍然要打开wifi，进入到mStaDisabledWithScanState状态。

接着上面的第二个步骤，当我们跳转到mDeviceActiveState之后，会继续相关逻辑处理。

WifiController状态机此时会用到，如下：

addState(mDefaultState);

addState(mStaDisabledState, mDefaultState);

addState(mStaEnabledState, mDefaultState);

addState(mDeviceActiveState, mStaEnabledState);

addState(mStaDisabledWithScanState, mDefaultState);

addState(mEcmState, mDefaultState);

进入到mDeviceActiveState之后会调用其enter方法，调用如下两个方法：

mWifiStateMachinePrime.enterClientMode();

mWifiStateMachine.setHighPerfModeEnabled(false);

通过查阅代码逻辑，可以看出：

/**

* Method to switch wifi into client mode where connections to configured networks will be

* attempted.

*/

public void enterClientMode() {

int mode = ModeStateMachine.CMD_START_CLIENT_MODE;

if (mIsSupportCucc) {

final FrameworkFacade facade = mWifiInjector.getFrameworkFacade();

int networktype = facade.getIntegerSetting(mContext,

Global.NETWORK_PREFERENCE, WIFI_DATA_TYPE);

int mobileDataStatus = facade.getIntegerSetting(mContext,

Global.MOBILE_DATA, MOBILE_DATA_ENABLE);

if (mobileDataStatus == MOBILE_DATA_ENABLE && networktype == MOBILE_DATA_TYPE) {

Log.d(TAG, "CUCC, client mode isn't allowed now, enter scan only mode");

mode = ModeStateMachine.CMD_START_SCAN_ONLY_MODE;

}

}

changeMode(mode);

}

看注释大意为：

使wifi跳转到client模式的一种方法，客户端模式中，