您的位置：首页 > 移动开发 > Android开发

Android WiFi Toggle ON/OFF流程分析

2014-07-17 18:58 316 查看

转自： http://blog.csdn.net/lilian0118/article/details/22376059

WiFi toggled on流程分析

这一章来分析一下从Settings打开wifi后，framework所有的流程以及状态转换，调用的主要函数就是WiFiMananger的setWifiEnabled(boolean enabled)，这个函数在前面介绍的WifiService启动流程中也有提到，当SystemServer
创建了个WifiService后，就会调用它的checkAndStartWifi，在这个函数里面，也同样会调用到setWifiEnabled(boolean enabled)，这是为了恢复用户在开机之前的wifi状态。下面来详细分析WifiMananger的setWifiEnabled函数。先来看看总体的流程图

对照上面的流程图，我们从WifiMananger的setWifiEnabled来分析一下代码：

[java] view
plaincopy

public boolean setWifiEnabled(boolean enabled) {

try {

return mService.setWifiEnabled(enabled);

} catch (RemoteException e) {

return false;

}

}

[java] view
plaincopy

WifiService.java

public synchronized boolean setWifiEnabled(boolean enable) {

enforceChangePermission();

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

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

if (DBG) {

Slog.e(TAG, "Invoking mWifiStateMachine.setWifiEnabled\n");

}

/*

* 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);

}

mWifiController.sendMessage(CMD_WIFI_TOGGLED);

return true;

}

在WifiService里面，先把传进来的参数写到WifiSettingsStore里面，WifiSettingsStore调用Settings提供的ContentProviders写到Sqlite的DB里面，所以我们看到mWifiController.sendMessage(CMD_WIFI_TOGGLED)是没有把这个参数传递过去的。接着去看WifiController里面如何处理CMD_WIFI_TOGGLED，由前面的WifiService启动流程分析，我们知道CMD_WIFI_TOGGLED将由WifiController的ApStaDisabledState来处理：

[java] view
plaincopy

class ApStaDisabledState extends State {

private int mDeferredEnableSerialNumber = 0;

private boolean mHaveDeferredEnable = false;

private long mDisabledTimestamp;

@Override

public void enter() {

mWifiStateMachine.setSupplicantRunning(false);

// Supplicant can't restart right away, so not the time we switched off

mDisabledTimestamp = SystemClock.elapsedRealtime();

mDeferredEnableSerialNumber++;

mHaveDeferredEnable = false;

}

@Override

public boolean processMessage(Message msg) {

switch (msg.what) {

case CMD_WIFI_TOGGLED:

case CMD_AIRPLANE_TOGGLED:

if (mSettingsStore.isWifiToggleEnabled()) {

if (doDeferEnable(msg)) {

if (mHaveDeferredEnable) {

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

mDeferredEnableSerialNumber++;

}

mHaveDeferredEnable = !mHaveDeferredEnable;

break;

}

if (mDeviceIdle == false) {

transitionTo(mDeviceActiveState);

} else {

checkLocksAndTransitionWhenDeviceIdle();

}

}

break;

WifiController的ApStaDisabledState的处理很简单，只是简单的transition到DeviceActiveState，因为DeviceActiveState的父State是StaEnabledState，由StateMachine的知识，我们先到StaEnabledState和DeviceActiveState的enter()函数来看看：

[java] view
plaincopy

class StaEnabledState extends State {

@Override

public void enter() {

mWifiStateMachine.setSupplicantRunning(true);

}

class DeviceActiveState extends State {

@Override

public void enter() {

mWifiStateMachine.setOperationalMode(WifiStateMachine.CONNECT_MODE);

mWifiStateMachine.setDriverStart(true);

mWifiStateMachine.setHighPerfModeEnabled(false);

}

上面分别是调用WifiStateMachine的四个函数，这四个函数都是给WifiStateMachine发送四个消息，分别是CMD_START_SUPPLICANT、SET_OPERATIONAL_MODE、CMD_START_DRIVER和SET_HTGH_PERF_MODE，如上图中的Figure 1所示。接着我们到WifiStateMachine的InitialState中去看看如何处理CMD_START_SUPPLICANT：

[java] view
plaincopy

public boolean processMessage(Message message) {

switch (message.what) {

case CMD_START_SUPPLICANT:

if (mWifiNative.loadDriver()) {

try {

mNwService.wifiFirmwareReload(mInterfaceName, "STA");

} catch (Exception e) {

loge("Failed to reload STA firmware " + e);

// continue

}

try {

mNwService.disableIpv6(mInterfaceName);

} catch (RemoteException re) {

loge("Unable to change interface settings: " + re);

} catch (IllegalStateException ie) {

loge("Unable to change interface settings: " + ie);

}

mWifiMonitor.killSupplicant(mP2pSupported);

if(mWifiNative.startSupplicant(mP2pSupported)) {

setWifiState(WIFI_STATE_ENABLING);

if (DBG) log("Supplicant start successful");

mWifiMonitor.startMonitoring();

transitionTo(mSupplicantStartingState);

} else {

loge("Failed to start supplicant!");

}

} else {

loge("Failed to load driver");

}

break;

这里主要调用WifiNative的loadDriver和startSupplicant两个函数去加载wifi driver和启动wpa_supplicant，当启动成功wpa_supplicant后，就会调用WifiMonitor的startMonitoring去和wpa_supplicant建立socket连接，并不断的从wpa_supplicant收event。wpa_supplicant是一个独立的运行程序，它和应用程序之间通过socket来通信，主要存在两个socket连接，一个用来向wpa_supplicant发送命令，另一个是wpa_supplicant用来向应用程序通知event，应用程序在收到event后可以知道当前的连接状态来进行下一步动作。我们进入到WifiMonitor.startMonitoring这个函数看看：

[java] view
plaincopy

public synchronized void startMonitoring(String iface) {

WifiMonitor m = mIfaceMap.get(iface);

if (m == null) {

Log.e(TAG, "startMonitor called with unknown iface=" + iface);

return;

}

Log.d(TAG, "startMonitoring(" + iface + ") with mConnected = " + mConnected);

if (mConnected) {

m.mMonitoring = true;

m.mWifiStateMachine.sendMessage(SUP_CONNECTION_EVENT);

} else {

if (DBG) Log.d(TAG, "connecting to supplicant");

int connectTries = 0;

while (true) {

if (mWifiNative.connectToSupplicant()) {

m.mMonitoring = true;

m.mWifiStateMachine.sendMessage(SUP_CONNECTION_EVENT);

new MonitorThread(mWifiNative, this).start();

mConnected = true;

break;

}

if (connectTries++ < 5) {

try {

Thread.sleep(1000);

} catch (InterruptedException ignore) {

}

} else {

mIfaceMap.remove(iface);

m.mWifiStateMachine.sendMessage(SUP_DISCONNECTION_EVENT);

Log.e(TAG, "startMonitoring(" + iface + ") failed!");

break;

}

}

}

}

这个方法里面主要调用WifiNative的connenctToSupplicant去和wpa_supplicant建立socket连接，然后给WifiStateMachine发送一个SUP_CONNECTION_EVENT消息，最后新建一个MonitorThread运行，MonitorThread就是一个循环，不断的从wpa_supplicant收event，然后进行解析，并dispatch到不同的函数去处理，后面我们再来分析MonitorThread的流程。回到WifiStateMachine的InitialState中去看看如何处理CMD_START_SUPPLICANT的流程中来，当startMonitoring结束后，WifiStateMachine就跳转到SupplicantStartingState，这时的WifiStateMachine和MessageQueue里面的消息队列上图中的Figure
2。

接着来看当WifiStateMachine处理完SUP_CONNECTION_EVENT消息后，马上会收到SET_OPERATIONAL_MODE和CMD_START_DRIVER消息，这两个消息都会被SupplicantStartingState延迟处理，SET_HTGH_PERF_MODE会被DefaultState处理。接着SupplicantStartingState会收到SUP_CONNECTION_EVENT，处理代码如下：

[java] view
plaincopy

public boolean processMessage(Message message) {

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);

/* Initialize data structures */

mLastBssid = null;

mLastNetworkId = WifiConfiguration.INVALID_NETWORK_ID;

mLastSignalLevel = -1;

mWifiInfo.setMacAddress(mWifiNative.getMacAddress());

mWifiConfigStore.loadAndEnableAllNetworks();

initializeWpsDetails();

sendSupplicantConnectionChangedBroadcast(true);

transitionTo(mDriverStartedState);

break;

在SUP_CONNECTION_EVENT的处理流程中，主要是调用WifiConfigStore的loadAndEnableAllNetworks函数来加载并enable用户之前连接过并保存的AP，然后会初始化一些Wps相关的信息，最后transition到DriverStartedState上，如上图的Figure
3。再来看DriverStartedState的enter函数，这里面有一些重要的流程：

[java] view
plaincopy

class DriverStartedState extends State {

@Override

public void enter() {

/* set country code */

setCountryCode();

/* set frequency band of operation */

setFrequencyBand();

/* initialize network state */

setNetworkDetailedState(DetailedState.DISCONNECTED);

mDhcpActive = false;

startBatchedScan();

if (mOperationalMode != CONNECT_MODE) {

mWifiNative.disconnect();

mWifiConfigStore.disableAllNetworks();

if (mOperationalMode == SCAN_ONLY_WITH_WIFI_OFF_MODE) {

setWifiState(WIFI_STATE_DISABLED);

}

transitionTo(mScanModeState);

} else {

/* Driver stop may have disabled networks, enable right after start */

mWifiConfigStore.enableAllNetworks();

if (DBG) log("Attempting to reconnect to wifi network ..");

mWifiNative.reconnect();

// Status pulls in the current supplicant state and network connection state

// events over the monitor connection. This helps framework sync up with

// current supplicant state

mWifiNative.status();

transitionTo(mDisconnectedState);

}

[java] view
plaincopy

[java] view
plaincopy

if (mP2pSupported) {

if (mOperationalMode == CONNECT_MODE) {

mWifiP2pChannel.sendMessage(WifiStateMachine.CMD_ENABLE_P2P);

} else {

// P2P statemachine starts in disabled state, and is not enabled until

// CMD_ENABLE_P2P is sent from here; so, nothing needs to be done to

// keep it disabled.

}

}

}

enter函数的代码比较多，上面是精简后的代码，上面主要分为两条分支，一是OperationalMode != CONNECT_MODE，一种是OperationalMode = CONNECT_MODE，根据官方的解释，OperationalMode一共有三种，分别如下：

1.CONNECT_MODE，这种模式下，STA可以scan并连接热点

2.SCAN_ONLY_MODE，这种模式下，STA只能扫描热点

3.SCAN_ONLY_WIFI_OFF_MODE，在这种模式下，当wifi是toggle off的情况下，也可以进行scan

这三种模式默认的是CONNECT_MODE，后面两种模式现在用到的不多，但按照Google的设计，后面可能会有很多的app会用到，比如利用热点来进行点位，这个应用其实这需要能够scan，并不需要链接热点。那我们接看这OperationalMode = CONNECT_MODE的流程，它直接transition 到DisconnectedState，如上图中的Figure 4，在transition到DisconnectedState之前，还会向WifiNative下reconnect的命令，用于重新连接上次连接但没有forget的AP，即开机后自动连上AP。如平台支持P2P，这里还将会给WifiP2pService发送CMD_ENABLE_P2P的消息，以后在学习P2P模块的时候再来分析。

到这里，Wifi toggle on的流程就分析完了。

WiFi toggled off流程分析

和Wifi toggle on的流程一样，当用户从Settings关闭wifi时，会调用WiFiMananger的setWifiEnabled(false)，接着WifiService会给WifiController发送一个CMD_WIFI_TOGGLED消息，由前面启动Wifi的流程来看，StaEabledState会处理这个消息，先看看整体的流程图：

进入到StaEabledState的processMessage来看看代码流程：

[java] view
plaincopy

public boolean processMessage(Message msg) {

switch (msg.what) {

case CMD_WIFI_TOGGLED:

if (! mSettingsStore.isWifiToggleEnabled()) {

if (mSettingsStore.isScanAlwaysAvailable()) {

transitionTo(mStaDisabledWithScanState);

} else {

transitionTo(mApStaDisabledState);

}

}

break;

WifiController会transition 到ApStaDisabledState中，这样WifiController这个状态机就回到的最开始的初始状态了，进到ApStaDisabledState的enter函数分析如何对WifiStateMachine这个状态机做处理：

[java] view
plaincopy

public boolean processMessage(Message message) {

switch(message.what) {

case CMD_STOP_SUPPLICANT: /* Supplicant stopped by user */

if (mP2pSupported) {

transitionTo(mWaitForP2pDisableState);

} else {

transitionTo(mSupplicantStoppingState);

}

break;

如果平台支持P2P，这里会跳转到WaitForP2pDisableState中，如果不支持则会跳转到SupplicantStoppingState中。这里我们看mP2pSupported为true的情况，因为现在大多数平台都应该支持P2P了，另外，在WaitForP2pDisableState中处理完P2P相关的内容后，也会跳转到SupplicantStoppingState中来。我们来分析WaitForP2pDisableState的enter函数：

[java] view
plaincopy

class WaitForP2pDisableState extends State {

private State mTransitionToState;

@Override

public void enter() {

switch (getCurrentMessage().what) {

case WifiMonitor.SUP_DISCONNECTION_EVENT:

mTransitionToState = mInitialState;

break;

case CMD_DELAYED_STOP_DRIVER:

mTransitionToState = mDriverStoppingState;

break;

case CMD_STOP_SUPPLICANT:

mTransitionToState = mSupplicantStoppingState;

break;

default:

mTransitionToState = mDriverStoppingState;

break;

}

mWifiP2pChannel.sendMessage(WifiStateMachine.CMD_DISABLE_P2P_REQ);

}

@Override

public boolean processMessage(Message message) {

switch(message.what) {

case WifiStateMachine.CMD_DISABLE_P2P_RSP:

transitionTo(mTransitionToState);

break;

mTransitionToState根据当前处理消息的不同种类，记录下次将要跳转到的State信息，然后给WifiP2pService发送一个CMD_DISABLE_P2P_REQ消息，P2P的内容后面再来分析，当P2P处理完CMD_DISABLE_P2P_REQ后，就会给WifiStateMachine发送一个CMD_DISABLE_P2P_RSP消息，在WaitForP2pDisableState收到这个消息后，就会跳转到SupplicantStoppingState中，再到这个函数的enter去看看：

[java] view
plaincopy

class SupplicantStoppingState extends State {

@Override

public void enter() {

/* Send any reset commands to supplicant before shutting it down */

handleNetworkDisconnect();

if (mDhcpStateMachine != null) {

mDhcpStateMachine.doQuit();

}

if (DBG) log("stopping supplicant");

mWifiMonitor.stopSupplicant();

/* Send ourselves a delayed message to indicate failure after a wait time */

sendMessageDelayed(obtainMessage(CMD_STOP_SUPPLICANT_FAILED,

++mSupplicantStopFailureToken, 0), SUPPLICANT_RESTART_INTERVAL_MSECS);

setWifiState(WIFI_STATE_DISABLING);

mSupplicantStateTracker.sendMessage(CMD_RESET_SUPPLICANT_STATE);

}

@Override

public boolean processMessage(Message message) {

switch(message.what) {

case WifiMonitor.SUP_CONNECTION_EVENT:

loge("Supplicant connection received while stopping");

break;

case WifiMonitor.SUP_DISCONNECTION_EVENT:

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

handleSupplicantConnectionLoss();

transitionTo(mInitialState);

break;

case CMD_STOP_SUPPLICANT_FAILED:

if (message.arg1 == mSupplicantStopFailureToken) {

loge("Timed out on a supplicant stop, kill and proceed");

handleSupplicantConnectionLoss();

transitionTo(mInitialState);

}

break;

在SupplicantStoppingState主要调用handleNetworkDisconnect和stopSupplicant函数，handleNetworkDisconnect主要工作是停掉stopDhcp和clear一些状态信息；WifiMonitor的stopSupplicant用于停掉wpa_supplicant，就是向wpa_supplicant发送一个TERMINATE命令，当wpa_supplicant收到TERMINATE命令会，就会给调用者发送CTRL-EVENT-TERMINATING这个event，当WifiMonitor收到这个event后，又会给WifiStateMachine发送SUP_DISCONNECTION_EVENT消息。回到SupplicantStoppingState收到这个消息后，就可以去结束掉wpa_supplicant进程并断开与它的socket连接，并且transition到InitialState，这样WifiStateMachine也恢复到最初的状态了。另外，从上面enter函数可以看到，还会发送一个CMD_STOP_SUPPLICANT_FAILED消息给自己，如果调用stopSupplicant不成功，间隔SUPPLICANT_RESTART_INTERVAL_MSECS毫秒后，也会走到和SUP_DISCONNECTION_EVENT消息处理一样的流程中来。

内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理

标签：

相关文章推荐

新的分享

章节导航