delphi 编程断开网络,该怎么解决

delphi 编程断开网络
请问如何断开网络连接
像个人防火墙一样
调用SetIfEntry   在XP下   没有任何效果

[解决办法]
看看代码吧。。。。禁用网络联接的例子，有点长

unit DeviceForm;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, CheckLst, Common, RegStr;

const
DEV_CLASS_NAME = 'Net ';
UNKNOWN_DEVICE = ' <未知设备> ';

type
TDevForm = class(TForm)
lbDev: TLabel;
btApply: TButton;
btExit: TButton;
clbDevList: TCheckListBox;
btRefresh: TButton;
procedure FormCreate(Sender: TObject);
procedure btExitClick(Sender: TObject);
procedure btApplyClick(Sender: TObject);
procedure btRefreshClick(Sender: TObject);
private
{ Private declarations }
DevState: Array of Boolean;
procedure RefreshDevState;

procedure EnumNetDevice;
function IsClassHidden(const ClassGUID: PGUID): Boolean;
function ConstructDeviceName(DeviceInfoSet: HDEVINFO;
DeviceInfoData: PSP_DEVINFO_DATA; Buffer: PAnsiChar; Length: ULONG): Boolean;
function GetRegistryProperty(DeviceInfoSet: HDEVINFO;
DeviceInfoData: PSP_DEVINFO_DATA; AProperty: ULONG; Buffer: PAnsiChar;
Length: ULONG): Boolean;
function IsDevDisable(DevIndex: DWORD; hDevInfo: HDEVINFO): Boolean;
function ChangeDevState(DevIndex, NewState: DWORD): BOOL;
public
{ Public declarations }
end;

var
DevForm: TDevForm;

implementation

{$R *.dfm}

procedure TDevForm.EnumNetDevice;
var
DeviceInfoSet: HDEVINFO;
DeviceInfoData: SP_DEVINFO_DATA;
i: Integer;
Status, Problem: DWORD;
ClassName: PChar;
ClassSize, ReqClassSize: DWORD;
DeviceName: PChar;
begin
clbDevList.Clear;

DeviceInfoSet:=SetupDiGetClassDevs(Nil,Nil,0,DIGCF_ALLCLASSES or DIGCF_PRESENT);
if DeviceInfoSet = Pointer(INVALID_HANDLE_VALUE) then
Exit;

ClassSize:=255;
GetMem(ClassName,256);
try
DeviceInfoData.cbSize := SizeOf(SP_DEVINFO_DATA);

i:=0;
while SetupDiEnumDeviceInfo(DeviceInfoSet,i,@DeviceInfoData) do
begin
Inc(i);

if not SetupDiClassNameFromGuid(@DeviceInfoData.ClassGuid,ClassName,ClassSize,
@ReqClassSize) then
begin
if ReqClassSize> ClassSize then
begin
FreeMem(ClassName);
ClassSize:=ReqClassSize;
GetMem(ClassName,ClassSize+1);
if not SetupDiClassNameFromGuid(@DeviceInfoData.ClassGuid,ClassName,ClassSize,
@ReqClassSize) then
Exit;
end
else
Exit;
end;

if not SameText(ClassName,DEV_CLASS_NAME) then
Continue;

if CM_Get_DevNode_Status(@Status, @Problem, DeviceInfoData.DevInst,0)
<> CR_SUCCESS then
Exit;

if ((Status and DN_NO_SHOW_IN_DM) <> 0) or
IsClassHidden(@DeviceInfoData.ClassGuid) then
Continue;

GetMem(DeviceName,256);
ZeroMemory(DeviceName,256);
ConstructDeviceName(DeviceInfoSet,@DeviceInfoData,DeviceName,255);
clbDevList.Items.AddObject(StrPas(DeviceName),TObject(i-1));
clbDevList.Checked[clbDevList.Count-1]:=IsDevDisable(i-1,DeviceInfoSet);
FreeMem(DeviceName);
end;
finally
FreeMem(ClassName);
SetupDiDestroyDeviceInfoList(DeviceInfoSet);

end;
end;

function TDevForm.ConstructDeviceName(DeviceInfoSet: HDEVINFO;
DeviceInfoData: PSP_DEVINFO_DATA; Buffer: PAnsiChar;
Length: ULONG): Boolean;
begin
Result:=True;

if not GetRegistryProperty(DeviceInfoSet,DeviceInfoData,SPDRP_FRIENDLYNAME,
Buffer,Length) then
begin
if not GetRegistryProperty(DeviceInfoSet,DeviceInfoData,SPDRP_DEVICEDESC,
Buffer,Length) then
begin
if not GetRegistryProperty(DeviceInfoSet,DeviceInfoData,SPDRP_CLASS,
Buffer,Length) then
begin
if not GetRegistryProperty(DeviceInfoSet,DeviceInfoData,SPDRP_CLASSGUID,
Buffer,Length) then
begin
StrCopy(Buffer,UNKNOWN_DEVICE);
end
else
Result:=False;
end
end
end;
end;

function TDevForm.GetRegistryProperty(DeviceInfoSet: HDEVINFO;
DeviceInfoData: PSP_DEVINFO_DATA; AProperty: ULONG; Buffer: PAnsiChar;
Length: ULONG): Boolean;
var
ReqLen: DWORD;
begin
Result:=False;

while not SetupDiGetDeviceRegistryProperty(DeviceInfoSet,DeviceInfoData,
AProperty,Nil,Buffer,Length,@ReqLen) do
begin
if GetLastError() = ERROR_INVALID_DATA then
break
else if GetLastError() = ERROR_INSUFFICIENT_BUFFER then
begin
if Assigned(Buffer) then
FreeMem(Buffer);
Length:=ReqLen;
GetMem(Buffer,Length+1);
end
else
Exit;
end;

Result:=Buffer^ <> #0;
end;

function TDevForm.IsClassHidden(const ClassGUID: PGUID): Boolean;
var
hKeyClass: HKEY;
begin
Result:=False;

hKeyClass := SetupDiOpenClassRegKey(ClassGuid,KEY_READ);
if hKeyClass <> 0 then
begin
Result:= RegQueryValueEx(hKeyClass,REGSTR_VAL_NODISPLAYCLASS,Nil,Nil,NIl,Nil) = ERROR_SUCCESS;
RegCloseKey(hKeyClass);
end;
end;

function TDevForm.IsDevDisable(DevIndex: DWORD;
hDevInfo: HDEVINFO): Boolean;
var
DeviceInfoData: SP_DEVINFO_DATA;
Status, Problem: DWORD;
begin
Result:=False;
DeviceInfoData.cbSize := SizeOf(SP_DEVINFO_DATA);

if not SetupDiEnumDeviceInfo(hDevInfo,DevIndex,@DeviceInfoData) then
Exit;

if CM_Get_DevNode_Status(@Status, @Problem, DeviceInfoData.DevInst, 0) <> CR_SUCCESS then
Exit;

Result:=((Status and DN_DISABLEABLE) <> 0) and (CM_PROB_HARDWARE_DISABLED <> Problem);
end;

function TDevForm.ChangeDevState(DevIndex, NewState: DWORD): BOOL;
var
DeviceInfoSet: HDEVINFO;
DeviceInfoData: SP_DEVINFO_DATA;
PropChangeParams: SP_PROPCHANGE_PARAMS;
Cursor: HCURSOR;
begin
Result:=False;

DeviceInfoSet:=SetupDiGetClassDevs(Nil,Nil,0,DIGCF_ALLCLASSES or DIGCF_PRESENT);
if DeviceInfoSet = Pointer(INVALID_HANDLE_VALUE) then
Exit;

try
PropChangeParams.ClassInstallHeader.cbSize:=SizeOf(SP_CLASSINSTALL_HEADER);
DeviceInfoData.cbSize:=SizeOf(SP_DEVINFO_DATA);

Cursor := SetCursor(LoadCursor(0, IDC_WAIT));

if not SetupDiEnumDeviceInfo(DeviceInfoSet,DevIndex,@DeviceInfoData) then
Exit;

PropChangeParams.ClassInstallHeader.InstallFunction := DIF_PROPERTYCHANGE;
PropChangeParams.Scope := DICS_FLAG_GLOBAL;
PropChangeParams.StateChange := NewState;

if not SetupDiSetClassInstallParams(DeviceInfoSet,@DeviceInfoData,
@PropChangeParams,Sizeof(PropChangeParams)) then
Exit;

if not SetupDiCallClassInstaller(DIF_PROPERTYCHANGE,DeviceInfoSet,

@DeviceInfoData) then
Exit;

SetCursor(Cursor);
Result:=True;
finally
SetupDiDestroyDeviceInfoList(DeviceInfoSet);
end;
end;

procedure TDevForm.FormCreate(Sender: TObject);
begin
btRefresh.Click;
end;

procedure TDevForm.btExitClick(Sender: TObject);
begin
Close;
end;

procedure TDevForm.btApplyClick(Sender: TObject);
var
i: Integer;
begin
for i:=0 to clbDevList.Count-1 do
begin
if clbDevList.Checked[i] <> DevState[i] then
begin
if clbDevList.Checked[i] then
ChangeDevState(Cardinal(clbDevList.Items.Objects[i]),DICS_ENABLE)
else
ChangeDevState(Cardinal(clbDevList.Items.Objects[i]),DICS_DISABLE)
end;
end;
RefreshDevState;
end;

procedure TDevForm.RefreshDevState;
var
i: Integer;
begin
SetLength(DevState,clbDevList.Count);
for i:=0 to clbDevList.Count-1 do
DevState[i]:=clbDevList.Checked[i];
end;

procedure TDevForm.btRefreshClick(Sender: TObject);
begin
EnumNetDevice;
RefreshDevState;
end;

end.