Delphi XE3探索：Winapi.Functiondiscovery （一）

思路分析

　　从Windows Vista开始SetupDi和WMI不再是唯一枚举和接收关于硬件信息的应用程序接口。随着Discovery的引入，你可以使用统一的API和接口访问已安装的硬件设备，用于收集功能,属性和NetBIOS,PNP，PNP-X等多种不同设备类型的信息。
Delphi XE3的Winapi.Functiondiscovery单元则封装了DiscoveryAPI,下面的基本代码用于枚举硬件设备。
　　调用收集设备信息（函数实例），必须要用到IFunctionDiscovery.GetInstanceCollection方法， 使用 IFunctionInstanceCollection.Item方法从集合中得到每个函数的实例，最后使用IFunctionInstance.OpenPropertyStore 和 IPropertyStore.GetValue方法检索每个属性值。

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.Win.ComObj,
  Winapi.Windows,
  Winapi.Activex,
  Winapi.PropSys,
  Winapi.Functiondiscovery,
  System.SysUtils;

procedure Enumerate;
var
    LFunctionDiscovery : IFunctionDiscovery;
    hr : HResult;
    i : integer;
    LFunctionInstance : IFunctionInstance;
    ppIFunctionInstanceCollection : IFunctionInstanceCollection;
    ppIPropertyStore  : IPropertyStore;
    pv : TPropVariant;
    pdwCount : DWORD;
    pszCategory: PWCHAR;
begin
  //create an instance to the  IFunctionDiscovery interface
  LFunctionDiscovery := CreateComObject(CLSID_FunctionDiscovery) as IFunctionDiscovery;
  try
    //set the provider to search
    pszCategory:=FCTN_CATEGORY_PNP;
    //get the devices collection
    hr := LFunctionDiscovery.GetInstanceCollection(pszCategory, nil, true, ppIFunctionInstanceCollection);
      //get the collection count
      if Succeeded(hr) and Succeeded(ppIFunctionInstanceCollection.GetCount(pdwCount)) then
      begin
        if pdwCount=0 then
          Writeln(Format('No items was found for the %s category',[pszCategory]))
        else
        for i := 0 to pdwCount - 1 do begin
          //get the n Item of the collection
          if Succeeded(ppIFunctionInstanceCollection.Item(i, LFunctionInstance)) then
          begin
            //init the propertiess store
            LFunctionInstance.OpenPropertyStore(STGM_READ, ppIPropertyStore);
            //read the properties values
            if Succeeded(ppIPropertyStore.GetValue(PKEY_NAME, pv)) then
             Writeln(Format('Name          %s',[pv.pwszVal]));
            if Succeeded(ppIPropertyStore.GetValue(PKEY_Device_InstanceId, pv)) then
             Writeln(Format('Instance Id   %s',[pv.pwszVal]));
            if Succeeded(ppIPropertyStore.GetValue(PKEY_Device_Driver, pv)) then
             Writeln(Format('Device Driver %s',[pv.pwszVal]));
            if Succeeded(ppIPropertyStore.GetValue(PKEY_Device_Model, pv)) then
             Writeln(Format('Model         %s',[pv.pwszVal]));
            if Succeeded(ppIPropertyStore.GetValue(PKEY_Device_Manufacturer, pv)) then
             Writeln(Format('Manufacturer  %s',[pv.pwszVal]));
            if Succeeded(ppIPropertyStore.GetValue(PKEY_Device_LocationInfo, pv)) then
             Writeln(Format('Location      %s',[pv.pwszVal]));
            Writeln;
          end
          else
           RaiseLastOSError;
        end;
      end
      else
       RaiseLastOSError;
  finally
    LFunctionDiscovery:=nil;
  end;
end;

begin
 try
   if (Win32MajorVersion >= 6) then  // available on Vista (or later)
   begin
    if Succeeded(CoInitializeEx(nil, COINIT_MULTITHREADED)) then
    try
     Enumerate;
    finally
      CoUninitialize;
    end;
   end
   else
   Writeln('Windows version not compatible');
 except
    on E:Exception do
        Writeln(E.Classname, ':', E.Message);
 end;
 Writeln('Press Enter to exit');
 Readln;
end.

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