Android Wifi 启动过程,AndroidP wifi启动流程
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，