WIFI模块WifiSettingsWirelessSettingsandroid_net_wifi_wifiwifiwpa_supplicantSocketWifiManagerWifiEnablerWifiServiceAIDLWifiMonitorWifiNatvieWifiStateTrackerAccessPointDialogJNIWifiLayerWIFI_STATE_CHANGED_ACTIONNETWORK_STATE_CHANGED_ACTIONSCAN_RESULTS_AVAILABLE_ACTIONSUPPLICANT_CONNECTION_CHANGE_ACTIONJAVAVM初始化在SystemServer启动的时候，会生成一个ConnectivityService的实例，try{Log.i(TAG,"StartingConnectivityService.");ServiceManager.addService(Context.CONNECTIVITY_SERVICE,newConnectivityService(context));}catch(Throwablee){Log.e(TAG,"FailurestartingConnectivityService",e);}ConnectivityService的构造函数会创建WifiService，if(DBG)Log.v(TAG,"StartingWifiService.");mWifiStateTracker=newWifiStateTracker(context,handler);WifiServicewifiService=newWifiService(context,mWifiStateTracker);ServiceManager.addService(Context.WIFI_SERVICE,wifiService);WifiStateTracker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。连接AP1.使能WIFIWirelessSettings在初始化的时候配置了由WifiEnabler来处理Wifi按钮，privatevoidinitToggles(){mWifiEnabler=newWifiEnabler(this,(WifiManager)getSystemService(WIFI_SERVICE),(CheckBoxPreference)findPreference(KEY_TOGGLE_WIFI));当用户按下Wifi按钮后，Android会调用WifiEnabler的onPreferenceChange，再由WifiEnabler调用WifiManager的setWifiEnabled接口函数，通过AIDL，实际调用的是WifiService的setWifiEnabled函数，WifiService接着向自身发送一条MESSAGE_ENABLE_WIFI消息，在处理该消息的代码中做真正的使能工作：首先装载WIFI内核模块（该模块的位置硬编码为"/system/lib/modules/wlan.ko"），然后启动wpa_supplicant（配置文件硬编码为"/data/misc/wifi/wpa_supplicant.conf"），再通过WifiStateTracker来启动WifiMonitor中的监视线程。privatebooleansetWifiEnabledBlocking(booleanenable){finalinteventualWifiState=enable?WIFI_STATE_ENABLED:WIFI_STATE_DISABLED;updateWifiState(enable?WIFI_STATE_ENABLING:WIFI_STATE_DISABLING);if(...
