android 4.0 WIFI 初始化过程（应用层+框架层）

android 4.0 wifi初始化（应用层 + 框架层）

1、在android/frameworks/base/services/java/com/android/server/目录下

SystemServer.java 中

class ServerThread extends Thread {

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@Override

public void run() {

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ConnectivityService connectivity = null;

WifiP2pService wifiP2p = null;

WifiService wifi = null;

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try { //实例化WifiP2pService

Slog.i(TAG, "Wi-Fi P2pService");

wifiP2p = new WifiP2pService(context);

ServiceManager.addService(Context.WIFI_P2P_SERVICE, wifiP2p);

} catch (Throwable e) {

reportWtf("starting Wi-Fi P2pService", e);

}

try { //实例化WifiService

Slog.i(TAG, "Wi-Fi Service");

wifi = new WifiService(context);

ServiceManager.addService(Context.WIFI_SERVICE, wifi);

} catch (Throwable e) {

reportWtf("starting Wi-Fi Service", e);

}

try { //实例化ConnectivityService

Slog.i(TAG, "Connectivity Service");

connectivity = new ConnectivityService(

context, networkManagement, networkStats, networkPolicy);

ServiceManager.addService(Context.CONNECTIVITY_SERVICE, connectivity);

networkStats.bindConnectivityManager(connectivity);

networkPolicy.bindConnectivityManager(connectivity);

wifi.checkAndStartWifi();

wifiP2p.connectivityServiceReady();

connectivity.startCne();

} catch (Throwable e) {

reportWtf("starting Connectivity Service", e);

}

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}

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}

在ServerThread.run()中实例化WifiP2pService、WifiService、ConnectivityService，并将三个服务均添加到ServiceManager中。在实例化ConnectivityService中，检测和启动wifi。

注释：对象实例化的同时就会分配存储空间，然后对成员变量进行初始化赋值，再执行构造函数。这个过程就是对象初始化。调用构造函数只是初始化的一部分。

有关于addService():

./base/core/java/android/os/ServiceManager.java

在android/frameworks/base/core/java/android/os/ServiceManager.java中：

public final class ServiceManager {

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/**

* Place a new @a service called @a name into the service

* manager.

*

* @param name the name of the new service

* @param service the service object

*/

public static void addService(String name, IBinder service) {

try {

getIServiceManager().addService(name, service, false);

} catch (RemoteException e) {

Log.e(TAG, "error in addService", e);

}

}

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}

由上可知：

ServiceManager.addService(Context.WIFI_SERVICE, wifi)：

将名字为“Context.WIFI_SERVICE”的wifi 服务添加到service manager中。

2、frameworks/base/services/java/com/android/server/ConnectivityService.java

在ConnectivityService 的构造函数会创建WifiStateTracker，

public class ConnectivityService extends IConnectivityManager.Stub {

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public ConnectivityService(Context context, INetworkManagementService netd,

INetworkStatsService statsService, INetworkPolicyManager policyManager)

{

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/*

* Create the network state trackers for Wi-Fi and mobile

* data. Maybe this could be done with a factory class,

* but it's not clear that it's worth it, given that

* the number of different network types is not going

* to change very often.

*/

//创建WifiStateTracker

for (int netType : mPriorityList) {

switch (mNetConfigs[netType].radio) {

case ConnectivityManager.TYPE_WIFI:

mNetTrackers[netType] = new WifiStateTracker(netType,

mNetConfigs[netType].name);

mNetTrackers[netType].startMonitoring(context, mHandler);

break;

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}

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}

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}

3、android/frameworks/base/wifi/java/android/net/wifi/WifiStateTracker.java

在WifiStateTracker中实例化WifiManager和WifiReceiver。

/**

* Track the state of wifi for connectivity service.

*

* @hide

*/

public class WifiStateTracker implements NetworkStateTracker {

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/**

* Begin monitoring wifi connectivity

*/

public void startMonitoring(Context context, Handler target) {

mCsHandler = target;

mContext = context;

mWifiManager=(WifiManager)mContext.getSystemService(Context.WIFI_SERVICE);

IntentFilter filter = new IntentFilter();

filter.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);

filter.addAction(WifiManager.LINK_CONFIGURATION_CHANGED_ACTION);

mWifiStateReceiver = new WifiStateReceiver();

mContext.registerReceiver(mWifiStateReceiver, filter);

}

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}

4、在WifiService中实例化WifiStateMachine，在WifiStateMachine中实例化WifiMonitor。

在android/frameworks/base/services/java/com/android/server中

WifiService.java：

/**

* WifiService handles remote WiFi operation requests by implementing

* the IWifiManager interface.

*/

//TODO: Clean up multiple locks and implement WifiService

// as a SM to track soft AP/client/adhoc bring up based

// on device idle state, airplane mode and boot.

public class WifiService extends IWifiManager.Stub {

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WifiService(Context context) {

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mWifiStateMachine = new WifiStateMachine(mContext, mInterfaceName);

mWifiStateMachine.enableRssiPolling(true);

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}

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}

在WifiStateMachine中实例化WifiMonoitor,

/**

* Track the state of Wifi connectivity. All event handling is done here,

* and all changes in connectivity state are initiated here.

*

* Wi-Fi now supports three modes of operation: Client, Soft Ap and Direct

* In the current implementation, we do not support any concurrency and thus only

* one of Client, Soft Ap or Direct operation is supported at any time.

*

* The WifiStateMachine supports Soft Ap and Client operations while WifiP2pService

* handles Direct. WifiP2pService and WifiStateMachine co-ordinate to ensure only

* one exists at a certain time.

*

* @hide

*/

public class WifiStateMachine extends StateMachine {

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private WifiMonitor mWifiMonitor;

mWifiMonitor = new WifiMonitor(this, mWifiNative);

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}

WifiStateMachine 会创建WifiMonitor 接收来自底层的事件，WifiService 和WifiMonitor 是整个模块的核心。WifiService 负责启动关闭wpa_supplicant、启动关闭WifiMonitor 监视线程和把命令下发给wpa_supplicant，而WifiMonitor 则负责从wpa_supplicant 接收事件通知。