Windows应用想要实现连接wifi，监听wifi信号，断开连接等功能，用NativeWifi API是个不错的选择。
打开MSDN,搜索NativeWifi Api，找到Native Wifi页。在这里。
信息量很大，如果像我着急实现上述功能，看海量的文档有些来不及。如果直接给我例子，在运行中调试，阅读代码，效率会更高。
但是，我并没有成功。首先，Sample在SDK
中，参见这里。我下载几次都失败了，最后放弃这条路。后来同事给了我一份Sample，我不敢确定是否就是这个，但是代码写的也是很晦涩。我的初衷是简单的使用这些API的例子。
看来还是自己动手吧。看相关API，如果不懂，就找有经验人的例子。
几经周折，终于实现我的需求。让我慢慢道来。
参见WlanGetAvailableNetworkList的官方文档，下面有例子。
DWORD WINAPI WlanGetAvailableNetworkList( _In_ HANDLE hClientHandle, _In_ const GUID *pInterfaceGuid, _In_ DWORD dwFlags, _Reserved_ PVOID pReserved, _Out_ PWLAN_AVAILABLE_NETWORK_LIST *ppAvailableNetworkList );
由可用列表便可以找到当前哪个AP正在连接，并显示信号强度。
在获得可用AP列表的基础上，遍历当前AP，看谁正在连接，并取得它的信号。代码片段如下：
bool isConnect = false;
int numberOfItems = pWLAN_AVAILABLE_NETWORK_LIST->dwNumberOfItems;
for(int i = 0; i <= numberOfItems; i++)
{
WLAN_AVAILABLE_NETWORK wlanAN = pWLAN_AVAILABLE_NETWORK_LIST->Network[i];
if(wlanAN.dwFlags & WLAN_AVAILABLE_NETWORK_CONNECTED)
{
Wprintf(WLAN signal is %s:%d\n", wlanAN.strProfileName, wlanAN.wlanSignalQuality);
isConnect = true;
}
}
if(!isConnect){
wprintf("Wifi is disconnected!\n");}
如果wifi处于连接状态，将其断开。WlanDisconnect还是容易使用的。原型如下：
DWORD WINAPI WlanDisconnect( _In_ HANDLE hClientHandle, _In_ const GUID *pInterfaceGuid, _Reserved_ PVOID pReserved );
代码演示在后面。
这是本文的重点。
虽然连接函数WlanConnect原型很简单：
DWORD WINAPI WlanConnect( _In_ HANDLE hClientHandle, _In_ const GUID *pInterfaceGuid, _In_ const PWLAN_CONNECTION_PARAMETERS pConnectionParameters, _Reserved_ PVOID pReserved );
但参数PWLAN_CONNECTION_PARAMETERS却是很复杂，只要有一个配错，连接就会失败。
还好我的需求还是蛮简单的，只要连接已有的profile的AP。那么我的工作就会有针对性的开展。挫折了好多天，每次都连接失败，原因是ERROR_INVALID_PARAMETER。
就在今天，我终于成功了。真是会者不难，难者不会啊。
看看连接参数的结构体：
typedef struct _WLAN_CONNECTION_PARAMETERS {
WLAN_CONNECTION_MODE wlanConnectionMode;
LPCWSTR strProfile;
PDOT11_SSID pDot11Ssid;
PDOT11_BSSID_LIST pDesiredBssidList;
DOT11_BSS_TYPE dot11BssType;
DWORD dwFlags;
} WLAN_CONNECTION_PARAMETERS, *PWLAN_CONNECTION_PARAMETERS;为了实现我的要求，可以这样赋值：
wlanConnectionMode这里设成wlan_connection_mode_profile
strProfile写上你要连接ap的名称（通常是profile名称）
pDot11Ssid用不上，设置NULL
pDesiredBssidList同样置成NULL
dot11BssType我给设成dot11_BSS_type_infrastructure（基础设施？）
dwFlags设置为WLAN_CONNECTION_HIDDEN_NETWORK
确实是工作了，strProfile如何获取呢？参见监听连接信号中对可用AP列表中第一个profile的获取。
完整代码如下：
//
#include "stdafx.h"
#include <windows.h>
#include <wlanapi.h>
#include <objbase.h>
#include <wtypes.h>
#include <string>
#include <stdio.h>
#include <stdlib.h>
// Need to link with Wlanapi.lib and Ole32.lib
#pragma comment(lib, "wlanapi.lib")
#pragma comment(lib, "ole32.lib")
using namespace std;
int listenStatus()
{
HANDLE hClient = NULL;
DWORD dwMaxClient = 2;
DWORD dwCurVersion = 0;
DWORD dwResult = 0;
DWORD dwRetVal = 0;
int iRet = 0;
WCHAR GuidString[39] = {0};
//Listen the status of the AP you connected.
while(1){
Sleep(5000);
PWLAN_INTERFACE_INFO_LIST pIfList = NULL;//I think wlan interface means network card
PWLAN_INTERFACE_INFO pIfInfo = NULL;
DWORD dwFlags = 0;
dwResult = WlanOpenHandle(dwMaxClient, NULL, &dwCurVersion, &hClient);
if (dwResult != ERROR_SUCCESS) {
wprintf(L"WlanOpenHandle failed with error: %u\n", dwResult);
return 1;
}
dwResult = WlanEnumInterfaces(hClient, NULL, &pIfList);
if (dwResult != ERROR_SUCCESS) {
wprintf(L"WlanEnumInterfaces failed with error: %u\n", dwResult);
return 1;
} else {
wprintf(L"WLAN_INTERFACE_INFO_LIST for this system\n");
wprintf(L"Num Entries: %lu\n", pIfList->dwNumberOfItems);
wprintf(L"Current Index: %lu\n\n", pIfList->dwIndex);
int i;
for (i = 0; i < (int) pIfList->dwNumberOfItems; i++) {
pIfInfo = (WLAN_INTERFACE_INFO *) &pIfList->InterfaceInfo[i];
wprintf(L" Interface Index[%u]:\t %lu\n", i, i);
iRet = StringFromGUID2(pIfInfo->InterfaceGuid, (LPOLESTR) &GuidString,
sizeof(GuidString)/sizeof(*GuidString));
if (iRet == 0)
wprintf(L"StringFromGUID2 failed\n");
else {
wprintf(L" InterfaceGUID[%d]: %ws\n",i, GuidString);
}
wprintf(L" Interface Description[%d]: %ws", i,
pIfInfo->strInterfaceDescription);
wprintf(L"\n");
wprintf(L" Interface State[%d]:\t ", i);
switch (pIfInfo->isState) {
case wlan_interface_state_not_ready:
wprintf(L"Not ready\n");
break;
case wlan_interface_state_connected:
wprintf(L"Connected\n");
break;
case wlan_interface_state_ad_hoc_network_formed:
wprintf(L"First node in a ad hoc network\n");
break;
case wlan_interface_state_disconnecting:
wprintf(L"Disconnecting\n");
break;
case wlan_interface_state_disconnected:
wprintf(L"Not connected\n");
break;
case wlan_interface_state_associating:
wprintf(L"Attempting to associate with a network\n");
break;
case wlan_interface_state_discovering:
wprintf(L"Auto configuration is discovering settings for the network\n");
break;
case wlan_interface_state_authenticating:
wprintf(L"In process of authenticating\n");
break;
default:
wprintf(L"Unknown state %ld\n", pIfInfo->isState);
break;
}
}
}
}
}
int _tmain(int argc, _TCHAR* argv[])
{
HANDLE hClient = NULL;
DWORD dwMaxClient = 2;
DWORD dwCurVersion = 0;
DWORD dwResult = 0;
DWORD dwRetVal = 0;
int iRet = 0;
/* variables used for WlanEnumInterfaces */
PWLAN_INTERFACE_INFO_LIST pIfList = NULL;
PWLAN_INTERFACE_INFO pIfInfo = NULL;
LPCWSTR pProfileName = NULL;
LPWSTR pProfileXml = NULL;
DWORD dwFlags = 0;
pProfileName = argv[1];
wprintf(L"Information for profile: %ws\n\n", pProfileName);
dwResult = WlanOpenHandle(dwMaxClient, NULL, &dwCurVersion, &hClient);
if (dwResult != ERROR_SUCCESS) {
wprintf(L"WlanOpenHandle failed with error: %u\n", dwResult);
return 1;
}
dwResult = WlanEnumInterfaces(hClient, NULL, &pIfList);
if (dwResult != ERROR_SUCCESS) {
wprintf(L"WlanEnumInterfaces failed with error: %u\n", dwResult);
return 1;
} else {
dwResult = WlanDisconnect(hClient, &pIfList->InterfaceInfo[0].InterfaceGuid,NULL);//DISCONNECT FIRST
if(dwResult != ERROR_SUCCESS)
{
printf("WlanDisconnect failed with error: %u\n",dwResult);
return -1;
}
PWLAN_AVAILABLE_NETWORK_LIST pWLAN_AVAILABLE_NETWORK_LIST = NULL;
dwResult = WlanGetAvailableNetworkList(hClient, &pIfList->InterfaceInfo[0].InterfaceGuid,
WLAN_AVAILABLE_NETWORK_INCLUDE_ALL_MANUAL_HIDDEN_PROFILES,
NULL, &pWLAN_AVAILABLE_NETWORK_LIST);
if (dwResult != ERROR_SUCCESS)
{
printf("WlanGetAvailableNetworkList failed with error: %u\n",dwResult);
WlanFreeMemory(pWLAN_AVAILABLE_NETWORK_LIST);
return -1;
}
WLAN_AVAILABLE_NETWORK wlanAN = pWLAN_AVAILABLE_NETWORK_LIST->Network[0];//PLEASE CHECK THIS YOURSELF
if(pProfileName == NULL)
pProfileName = wlanAN.strProfileName;
WLAN_CONNECTION_PARAMETERS wlanConnPara;
wlanConnPara.wlanConnectionMode =wlan_connection_mode_profile ; //YES,WE CONNECT AP VIA THE PROFILE
wlanConnPara.strProfile =pProfileName; // set the profile name
wlanConnPara.pDot11Ssid = NULL; // SET SSID NULL
wlanConnPara.dot11BssType = dot11_BSS_type_infrastructure; //dot11_BSS_type_any,I do not need it this time.
wlanConnPara.pDesiredBssidList = NULL; // the desired BSSID list is empty
wlanConnPara.dwFlags = WLAN_CONNECTION_HIDDEN_NETWORK; //it works on my WIN7\8
dwResult=WlanConnect(hClient,&pIfList->InterfaceInfo[0].InterfaceGuid,&wlanConnPara ,NULL);
if (dwResult==ERROR_SUCCESS)
{
printf("WlanConnect success!\n");
}
else
{
printf("WlanConnect failed err is %d\n",dwResult);
}
}
listenStatus(); //LISTEN THE STATUS
if (pProfileXml != NULL) {
WlanFreeMemory(pProfileXml);
pProfileXml = NULL;
}
if (pIfList != NULL) {
WlanFreeMemory(pIfList);
pIfList = NULL;
}
return dwRetVal;
}
遇到以前没有连接过的AP，需要输入密码，那么，直接打开配置界面让用户自己来搞吧。
ShellExecute(
NULL,
L"open",
L"shell:::{21EC2020-3AEA-1069-A2DD-08002B30309D}\\::{38a98528-6cbf-4ca9-8dc0-b1e1d10f7b1b}",
NULL,
NULL,
SW_SHOWNORMAL);
6.最后
当屏幕上打印出“WlanConnect success!”的时候，别提多高兴了。
就像爱迪生试验灯丝一下，在无数次失败后，终于找到了一种材料可以胜任灯丝的工作。这种喜悦真的令人振奋，往日的阴霾和不爽终于一扫而光。
其实我也尝试过WlanGetProfile和WlanSetProfile，虽然有时结果是能够连上指定AP，但是函数返回结果却总是ERROR_INVALID_PARAMETER。
网上的例子，很多都是抄来抄去的，写的不明不白，虽然有过帮助，但是也有些误导。
今天自己成功的连接到指定AP了（用命令行运行我的例子，输入参数profile name），我一定要把它发表出来，让其他人有个参考。
我认为这是一件诚意的作品，在此也谢谢给过我帮助的朋友。
最后说一下获得的信号。标准信号RSSI是负值，而这里获得的信号都是正值（0~100），在有些需要RSSI的地方，我们需要转换一下：
if (pBssEntry->wlanSignalQuality == 0)
iRSSI = -100;
else if (pBssEntry->wlanSignalQuality == 100)
iRSSI = -50;
else
iRSSI = -100 + (pBssEntry->wlanSignalQuality/2);
wprintf(L" Signal Quality[%u]:\t %u (RSSI: %i dBm)\n", j,
pBssEntry->wlanSignalQuality, iRSSI);