在Android上实现WLAN的一点理解

众所周知，Android 是基于Linux内核的，所以直接支持Linux的WLAN接口。WLAN的内核驱动是根据用户在UI上的设定动态加载的，通过ctrl_interface和openssl来实现WLAN的控制和安全性，TCPIP则基于WLAN的标准实现。

WLAN  在Android上的体系构架如下：

Application Framework : base/wifi/java/android/net/wifi

                                WifiManager/WifiMonitor/WifiConfiguration …

Service Framework: base/services/java/com/android/server/

                                WifiService / WifiWatchdogService

JNI (Java Native Interface)

                                jni/android_net_wifi_Wifi.cpp

HAL (Hardware Abstract Layer)

                                hardware/libhardware/wifi/wifi.c

                                wpa_supplicant / ctrl_interface

Kernel driver

在Android手机上打开WIFI的流程如下:

1)Application Framework: WifiManager

                                setWifiEnabled()

2)Service: WifiService

                                setWifiEnabled()

                                handleMessage() : MESSAGE_ENABLE_WIFI

3)JNI: android_net_wifi_Wifi.cpp :

                                JNINativeMethod:  loadDriver

                                android_net_wifi_loadDriver()

4)HAL : hardware/libhardware/wifi/wifi.c

                                wifi_load_driver()

5)Kernel : 加载内核驱动

WLAN的搜索流程如下：

1）Application Framework: WifiManager

                                startScan()

2）Service:

                WifiService::startScan()

                WifiNative::scanCommand();

3）JNI: android_net_wifi_Wifi.cpp :

                                JNINativeMethod:  scanCommand / scanResultsCommand

                                android_net_wifi_scanCommand / android_net_wifi_scanResultsCommand

4）HAL : hardware/libhardware/wifi/wifi.c

                                wifi_send_command : SCAN / SCAN_RESULTS

                        wpa_supplicant/driver_wext.c

                                wpa_driver_wext_scan() : SIOCSIWSCAN

5）Kernel : WLAN 驱动处理相关接口的命令

WAPI是我国WLAN的国家标准----- GB 15629.11,并予以802.11i兼容，在Android上的实现只需增加相应的鉴权即可。