在Android系統啓動的時候，會在./frameworks/base/services/java/com/android/server/SystemServer.java類中啓動許多服務，其中和Wifi相關的服務就在這裏初始化。在SystemServer的main方法中，我們可以看到
thr.initAndLoop();這裏調用了它的內部類對象的initAndLoop方法，在這個方法的作用主要就是初始化系統啓動需要加載的服務的，我們在這個方法中可以找到
try {
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 {
Slog.i(TAG, "Connectivity Service");
connectivity = new ConnectivityService(
context, networkManagement, networkStats, networkPolicy);
ServiceManager.addService(Context.CONNECTIVITY_SERVICE, connectivity);
networkStats.bindConnectivityManager(connectivity);
networkPolicy.bindConnectivityManager(connectivity);
wifiP2p.connectivityServiceReady();
wifi.checkAndStartWifi();
} catch (Throwable e) {
reportWtf("starting Connectivity Service", e);
}
這裏我們可以看到初始化了一個WifiService和ConnectivityService對象，並把這2個對象註冊到ServiceManager中，然後通過創建的對象wifi 來調用checkAndStartWifi方法，具體的WifiService的分析我們下一章再做詳細介紹，現在我們簡單分析下ConnectivityService。
ConnectivityService是管理系統中所有的數據連接服務，其中就包括Wifi，我們來看看它的構造函數，路徑：./frameworks/base/services/java/com/android/server/ConnectivityService.java
public ConnectivityService(Context context, INetworkManagementService netd,
INetworkStatsService statsService, INetworkPolicyManager policyManager) {
// Currently, omitting a NetworkFactory will create one internally
// TODO: create here when we have cleaner WiMAX support
this(context, netd, statsService, policyManager, null);
}public ConnectivityService(Context context, INetworkManagementService netManager,
INetworkStatsService statsService, INetworkPolicyManager policyManager,
NetworkFactory netFactory) {
if (DBG) log("ConnectivityService starting up");
HandlerThread handlerThread = new HandlerThread("ConnectivityServiceThread");
handlerThread.start();
mHandler = new InternalHandler(handlerThread.getLooper());
mTrackerHandler = new NetworkStateTrackerHandler(handlerThread.getLooper());
// Create and start trackers for hard-coded networks
for (int targetNetworkType : mPriorityList) {
final NetworkConfig config = mNetConfigs[targetNetworkType];
final NetworkStateTracker tracker;
try {
/** M: Hotspot Manager @{*/
if(config.radio == TYPE_USB){
log("new UsbDataStateTracker");
mNetTrackers[targetNetworkType] = new UsbDataStateTracker(targetNetworkType, config.name, mNetd);
mNetTrackers[targetNetworkType].startMonitoring(context, mTrackerHandler);
continue;
}
if(true == FeatureOption.MTK_ALPS_BOX_SUPPORT && config.radio == TYPE_ETHERNET){
if (DBG) log("Starting Ethernet Service.");
mNetTrackers[TYPE_ETHERNET] = makeEthStateTracker(context);
if(mNetTrackers[TYPE_ETHERNET] != null){
if (DBG) log("mNetTrackers[TYPE_ETHERNET] != null");
mNetTrackers[TYPE_ETHERNET].startMonitoring(context, mTrackerHandler);
if (config.isDefault()) {
mNetTrackers[TYPE_ETHERNET].reconnect();
}
}
continue;
}
/*@} */
/*@} */
///M:new a Teledongle Data Tracker @by mtk94127 @{
if(FeatureOption.MTK_EXTERNAL_DONGLE_SUPPORT && (config.radio == TYPE_TEDONGLE)) {
log("new TedongleDataStateTracker");
mNetTrackers[targetNetworkType] = makeTedongleDataTracker();
log("new TedongleDataStateTracker medium!");
mNetTrackers[targetNetworkType].startMonitoring(context, mTrackerHandler);
log("new TedongleDataStateTracker end!");
continue;
}
///M:@}
tracker = netFactory.createTracker(targetNetworkType, config);
mNetTrackers[targetNetworkType] = tracker;
} catch (IllegalArgumentException e) {
Slog.e(TAG, "Problem creating " + getNetworkTypeName(targetNetworkType)
+ " tracker: " + e);
continue;
}
tracker.startMonitoring(context, mTrackerHandler);
if (config.isDefault()) {
tracker.reconnect();
}
}
}這裏根據com.android.internal.R.array.networkAttributes配置的屬性去創建一個個tracker，並監聽其狀態，tracker.startMonitoring(context, mTrackerHandler);可以看出tracker可以通過mTrackerHandler向ConnectivityService發送消息，這些消息有
/**
* The network state has changed and the NetworkInfo object
* contains the new state.
*
* msg.what = EVENT_STATE_CHANGED
* msg.obj = NetworkInfo object
*/
public static final int EVENT_STATE_CHANGED = BASE_NETWORK_STATE_TRACKER;
/**
* msg.what = EVENT_CONFIGURATION_CHANGED
* msg.obj = NetworkInfo object
*/
public static final int EVENT_CONFIGURATION_CHANGED = BASE_NETWORK_STATE_TRACKER + 1;
/**
* msg.what = EVENT_RESTORE_DEFAULT_NETWORK
* msg.obj = FeatureUser object
*/
public static final int EVENT_RESTORE_DEFAULT_NETWORK = BASE_NETWORK_STATE_TRACKER + 2;
/**
* msg.what = EVENT_NETWORK_SUBTYPE_CHANGED
* msg.obj = NetworkInfo object
*/
public static final int EVENT_NETWORK_SUBTYPE_CHANGED = BASE_NETWORK_STATE_TRACKER + 3;
/**
* msg.what = EVENT_NETWORK_CONNECTED
* msg.obj = LinkProperties object
*/
public static final int EVENT_NETWORK_CONNECTED = BASE_NETWORK_STATE_TRACKER + 4;
/**
* msg.what = EVENT_NETWORK_CONNECTION_DISCONNECTED
* msg.obj = LinkProperties object, same iface name
*/
public static final int EVENT_NETWORK_DISCONNECTED = BASE_NETWORK_STATE_TRACKER + 5;
當WiFi的連接AP成功後，就會想 ConnectivityService發送一個EVENT_STATE_CHANGED消息。
接着我們來看創建了哪些tracker，找到createTracker方法
@Override
public NetworkStateTracker createTracker(int targetNetworkType, NetworkConfig config) {
switch (config.radio) {
case TYPE_WIFI:
return new WifiStateTracker(targetNetworkType, config.name);
case TYPE_MOBILE:
return new MobileDataStateTracker(targetNetworkType, config.name);
case TYPE_DUMMY:
return new DummyDataStateTracker(targetNetworkType, config.name);
case TYPE_BLUETOOTH:
return BluetoothTetheringDataTracker.getInstance();
case TYPE_WIMAX:
return makeWimaxStateTracker(mContext, mTrackerHandler);
case TYPE_CSD:
return new CsdStateTracker(targetNetworkType, config.name);
default:
throw new IllegalArgumentException(
"Trying to create a NetworkStateTracker for an unknown radio type: "
+ config.radio);
}
}這裏我們主要關注TYPE_WIFI，創建了一個WifiStateTracker對象，進入到WifiStateTracker的構造方法
public WifiStateTracker(int netType, String networkName) {
///M:@{
mNetType = netType;
///@}
mNetworkInfo = new NetworkInfo(netType, 0, networkName, "");
mLinkProperties = new LinkProperties();
mLinkCapabilities = new LinkCapabilities();
mNetworkInfo.setIsAvailable(false);
setTeardownRequested(false);
}接着調用startMonitoring
/**
* 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();
///M:seperate p2p and wifi @{
if (mNetType == ConnectivityManager.TYPE_WIFI) {
filter.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);
filter.addAction(WifiManager.LINK_CONFIGURATION_CHANGED_ACTION);
}
///@}
mWifiStateReceiver = new WifiStateReceiver();
mContext.registerReceiver(mWifiStateReceiver, filter);
}這裏就是註冊了一個廣播用於接收NETWORK_STATE_CHANGED_ACTION和LINK_CONFIGURATION_CHANGED_ACTION廣播，ConnectivityService我們就分析到這裏，下一章我們將詳細分析WifiService。