Android Wifi 启动过程,AndroidP wifi启动流程
從AndroidO到AndroidP，Wifi架構上還是發生了挺多變化的。接口上也在發生變化，所以網上的很多的流程梳理已經跟當前的代碼邏輯有一些差異了。不過還好，總體上，只要懂了一個版本的代碼，看其他版本問題已經不是很大。
梳理還是簡單易懂為要務。
調用WifiManager中的setWifiEabled()開啟wifi：
public boolean setWifiEnabled(boolean enabled) {
try {
return mService.setWifiEnabled(getContext().getOpPackageName(), enabled);
} catch (RemoteException e) {
throw e.rethrowFromSystemServer();
}
}
通過aidl調用到系統進程中的服務類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;
}
此段代碼邏輯中有涉及到權限檢測，以及wifi開關狀態保存等操作，最終調用到了如下方法：
mWifiController.sendMessage(CMD_WIFI_TOGGLED);
WifiController是一個狀態機，接收到消息會根據處理邏輯進行不同狀態的跳轉，如下代碼
if (checkScanOnlyModeAvailable()) {
setInitialState(mStaDisabledWithScanState);
} else {
setInitialState(mStaDisabledState);
}
WifiController的初始狀態為mStaDisabledState，所以CMD_WIFI_TOGGLED消息應該在此狀態下處理，查看其處理邏輯：
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;
代碼邏輯大致為：
先判斷當前設備狀態是否支持打開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;
}
}
有涉及到飛行模式的相關考慮。
檢測是否兩次點擊調用開啟wifi是否時間差太短，如果太短，消息延時處理，否則的話直接跳轉到mDeviceActiveState
如果wifi當前不支持打開，而此時“wifi scan always開關”打開，我們仍然要打開wifi，進入到mStaDisabledWithScanState狀態。
接著上面的第二個步驟，當我們跳轉到mDeviceActiveState之后，會繼續相關邏輯處理。
WifiController狀態機此時會用到，如下：
addState(mDefaultState);
addState(mStaDisabledState, mDefaultState);
addState(mStaEnabledState, mDefaultState);
addState(mDeviceActiveState, mStaEnabledState);
addState(mStaDisabledWithScanState, mDefaultState);
addState(mEcmState, mDefaultState);
進入到mDeviceActiveState之后會調用其enter方法，調用如下兩個方法：
mWifiStateMachinePrime.enterClientMode();
mWifiStateMachine.setHighPerfModeEnabled(false);
通過查閱代碼邏輯，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);
}
看注釋大意為：
使wifi跳轉到client模式的一種方法，客戶端模式中，
總結
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