如何判断网络是否连接？

[wshuo]

编写一个计费软件，用什么方法判断网络是否连接？要支持电话拨号、宽带等上网方式。

[AustinLei]

function InternetGetConnectedState(dwFlags:Longint;dwReserved:Longint):longint;stdcall;external 'wininet.dll';
function IsConnected():Boolean;

implementation

{$R *.dfm}

function IsConnected():Boolean;
begin
If InternetGetConnectedState(0, 0)=1 Then
IsConnected:=True
Else
IsConnected:=False;
end;

[wshuo]

检测结果，始终是连接状态，XP下试验的。

[cjsh]

{=================================================================
功 能: 检测计算机是否上网
参 数: 无
返回值: 成功: True 失败: False;
备 注: uses Wininet
版 本: 1.0 2003/08/11
=================================================================}
function InternetConnected: Boolean;
const
// local system uses a modem to connect to the Internet.
INTERNET_CONNECTION_MODEM = 1;
// local system uses a local area network to connect to the Internet.
INTERNET_CONNECTION_LAN = 2;
// local system uses a proxy server to connect to the Internet.
INTERNET_CONNECTION_PROXY = 4;
// local system's modem is busy with a non-Internet connection.
INTERNET_CONNECTION_MODEM_BUSY = 8;
var
dwConnectionTypes : DWORD;
begin
dwConnectionTypes := INTERNET_CONNECTION_MODEM+ INTERNET_CONNECTION_LAN
+ INTERNET_CONNECTION_PROXY;
Result := InternetGetConnectedState(@dwConnectionTypes, 0);
end;