Сообщество Чайников

Вопрос

Как проверить, если ли соединение с инетом? Т.е., чтобы прога не трудила зря.

Ответ

«КАК ПРОВЕРИТЬ СОЕДИНЕНИЕ С ИНТЕРНЕТОМ И УЗНАТЬ ТИП СОЕДИНЕНИЯ»

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По нажатию на кнопку в появляется сообщение. Если не 0 — есть соединения с Интернетом. А в заголовке формы показывается тип соединения.

unit Unit1;
interface uses Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, Registry, WinSock, WinInet, StdCtrls;
type TConnectionType = (ctNone, ctProxy, ctDialup);
function ConnectedToInternet : TConnectionType;
function RasConnectionCount : Integer;
type TForm1 = class(TForm) Button1: TButton;
procedure Button1Click(Sender: TObject);
private { Private declarations } public { Public declarations } end;
var Form1: TForm1;
implementation {$R *.DFM} //For RasConnectionCount ======================= const cERROR_BUFFER_TOO_SMALL = 603;
cRAS_MaxEntryName = 256;
cRAS_MaxDeviceName = 128;
cRAS_MaxDeviceType = 16;
type ERasError = class(Exception);
HRASConn = DWord; PRASConn = ^TRASConn;
TRASConn = record dwSize: DWORD; rasConn: HRASConn;
szEntryName: Array[0..cRAS_MaxEntryName] Of Char;
szDeviceType : Array[0..cRAS_MaxDeviceType] Of Char;
szDeviceName : Array [0..cRAS_MaxDeviceName] of char;
end;
TRasEnumConnections = function (RASConn: PrasConn; { buffer to receive Connections data } var BufSize: DWord; { size in bytes of buffer } var Connections: DWord { number of Connections written to buffer } ): LongInt; stdcall;
//End RasConnectionCount ======================= function ConnectedToInternet: TConnectionType; var Reg : TRegistry; bUseProxy : Boolean; UseProxy : LongWord;
begin Result := ctNone;
Reg := TRegistry.Create; with REG do try try RootKey := HKEY_CURRENT_USER;
if OpenKey('\Software\Microsoft\Windows\CurrentVersion\Internet settings',False) then begin //I just try to read it, and trap an exception if GetDataType('ProxyEnable') = rdBinary then ReadBinaryData('ProxyEnable', UseProxy, SizeOf(LongWord) ) else begin bUseProxy := ReadBool('ProxyEnable');
if bUseProxy then UseProxy := 1 else UseProxy := 0;
end;
if (UseProxy <> 0) and ( ReadString('ProxyServer') <> '' ) then Result := ctProxy;
end;
except //Obviously not connected through a proxy end; finally Free;
end;
//We can check RasConnectionCount even if dialup networking is not installed //simply because it will return 0 if the DLL is not found. if Result = ctNone then begin if RasConnectionCount > 0 then Result := ctDialup;
end;
end;
function RasConnectionCount : Integer;
var RasDLL : HInst; Conns : Array[1..4] of TRasConn; RasEnums : TRasEnumConnections; BufSize : DWord;
NumConns : DWord;
RasResult : Longint;
begin Result := 0;
//Load the RAS DLL RasDLL := LoadLibrary('rasapi32.dll');
if RasDLL = 0 then exit;
try RasEnums := GetProcAddress(RasDLL,'RasEnumConnectionsA');
if @RasEnums = nil then raise ERasError.Create('RasEnumConnectionsA not found in rasapi32.dll');
Conns[1].dwSize := Sizeof (Conns[1]);
BufSize := SizeOf(Conns);
RasResult := RasEnums(@Conns, BufSize, NumConns);
If (RasResult = 0) or (Result = cERROR_BUFFER_TOO_SMALL) then Result := NumConns;
finally FreeLibrary(RasDLL);
end;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin ShowMessage(IntToStr(RasConnectionCount));
if ConnectedToInternet=ctNone then Form1.Caption:='ctNone';
if ConnectedToInternet=ctProxy then Form1.Caption:='ctProxy';
if ConnectedToInternet=ctDialup then Form1.Caption:='ctDialup';
end;
end.

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