https://wireless.wiki.kernel.org/en/developers/Regulatory/CRDA
    目前可以使用wireless-tools 或wpa_supplicant工具来配置无线网络。请记住重要的一点是，对无线网络的配置是全局性的，而非针对具体的接口。

    wpa_supplicant是一个较好的选择，但缺点是它不支持所有的驱动。请浏览wpa_supplicant网站获得它所支持的驱动列表。另外，wpa_supplicant目前只能连接到那些你已经配置好ESSID的无线网络。wireless-tools支持几乎所有的无线网卡和驱动，但它不能连接到那些只支持WPA的AP。
    经过编译后的wpa_supplicant源程序可以看到两个主要的可执行工具：wpa_supplicant和wpa_cli。wpa_supplicant是核心程序，它和wpa_cli的关系就是服务和客户端的关系：后台运行wpa_supplicant，使用wpa_cli来搜索、设置、和连接网络。
    如何用wpa_supplicant使能一个wifi连接？
    Step by step：
    1、运行wpa_supplicant程序；
    执行：/system/bin/wpa_supplicant -d -Dwext -iwlan0 -c/data/misc/wifi/wpa_supplicant.conf
    其中：
    -d ：增加调试信息
    -Dwext ：wext，驱动名称
    -iwlan0 ：wlan0，网络接口名称
    /system/bin/wpa_supplicant ：wpa_supplicant可执行程序path
    /data/misc/wifi/wpa_supplicant.conf ：wpa_supplicant的配置文件path
    2、运行命令行工具wpa_cli ；
    执行 ：wpa_cli -iwlan0 -p/data/system/wpa_supplicant
    注，-p/data/system/wpa_supplicant中的wpa_supplicant并不是可执行程序，而是个控制套接字。
    此时会进入交互模式。其中交互模式的命令如下表：

    Full command Short command Description
    status stat displays the current connection status
    disconnect disc prevents wpa_supplicant from connecting to any access point
    quit q exits wpa_cli
    terminate term kills wpa_supplicant
    reconfigure recon reloads wpa_supplicant with the configuration file supplied (-c parameter)
    scan scan scans for available access points (only scans it, doesn’t display anything)
    scan_result scan_r displays the results of the last scan
    list_networks list_n displays a list of configured networks and their status (active or not, enabled or disabled)
    select_network select_n select a network among those defined to initiate a connection (ie select_network 0)
    enable_network enable_n makes a configured network available for selection (ie enable_network 0)
    disable_network disable_n makes a configured network unavailable for selection (ie disable_network 0)
    remove_network remove_n removes a network and its configuration from the list (ie remove_network 0)
    add_network add_n adds a new network to the list. Its id will be created automatically
    set_network set_n shows a very short list of available options to configure a network when supplied with no parameters.
    See next section for a list of extremely useful parameters to be used with set_network and get_network.
    get_network get_n displays the required parameter for the specified network. See next section for a list of parameters
    save_config save_c saves the configuration


    设置网络的基本格式：set_network []
    显示网络信息的基本格式：get_network
    相应的参数如下表：

    Key Description Parameters
    ssid Access point name string
    id_str String identifying the network string
    priority Connection priority over other APs number (0 being the default low priority)
    bssid Mac address of the access point mac address
    scan_ssid Enable/disbale ssid scan 0, 1, 2
    key_mgmt Type of key management WPA-PSK, WPA_EAP, None
    pairwise Pairwise ciphers for WPA CCMP, TKIP
    group=TKIP Group ciphers for WPA CCMP, TKIP, WEP104, WEP40
    psk Pre-Shared Key (clear or encrypted) string
    wep_key0 WEP key (up to 4: wep_key[0123]) string
    eap Extensible Authentication Protocol MD5, MSCHAPV2, OTP, GTC, TLS, PEAP, TTLS
    identity EAP identity string string
    password EAP password string
    ca_cert Pathname to CA certificate file /full/path/to/certificate
    client_cert Pathname to client certificate /full/path/to/certificate (PEM/DER)
    private_key Pathname to a client private key file /full/path/to/private_key (PEM/DER/PFX)



    eg.1、连接无加密的AP
    >add_network (It will display a network id for you, assume it returns 0)
    >set_network 0 ssid “666”
    >set_network 0 key_mgmt NONE
    >enable_network 0
    >quit
    eg.2、连接WEP加密AP
    >add_network (assume return 1)
    >set_network 1 ssid “666”
    >set_network 1 key_mgmt NONE
    >set_network 1 wep_key0 “your ap password”
    >enable_network 1
    eg.3、连接WPA-PSK/WPA2-PSK加密的AP
    >add_network (assume return 2)
    >set_network 2 ssid “666”
    >set_network 2 psk “your pre-shared key”
    >enable_network 2
    到此，wifi模块就能连接上AP了。
    3、以上是通过命令行工具wpa_cli来实现wifi网络的连接。当然，也可以通过wpa_supplicant的配置文件来实现连接。
    再回顾下运行wpa_supplicant时执行的命令：
    /system/bin/wpa_supplicant -d -Dwext -iwlan0 -c/data/misc/wifi/wpa_supplicant.conf
    我们在执行时加上了-c/data/misc/wifi/wpa_supplicant.conf，我们可以将我们要连接的AP的设置以一定的格式写入wpa_supplicant.conf配置文件中即可。
    eg.
    ctrl_interface=DIR=/data/system/wpa_supplicant GROUP=system update_config=1
    network={
    ssid=”my access point”
    proto=WPA
    key_mgmt=WPA-PSK
    psk=”you pass words”
    }