学步园

  //功能:检测计算机是否上网
  //返回值:成功:True 失败:False;
  //需要引用 uses wininet
  function InternetConnected:Boolean;StdCall;
  const  
      INTERNET_CONNECTION_MODEM=1;
      INTERNET_CONNECTION_LAN=2;
      INTERNET_CONNECTION_PROXY=4;
      INTERNET_CONNECTION_MODEM_BUSY=8;
  var  
      dwConnectionTypes:DWORD;
  begin  
      dwConnectionTypes:=INTERNET_CONNECTION_MODEM+INTERNET_CONNECTION_LAN+INTERNET_CONNECTION_PROXY;
      Result:=InternetGetConnectedState(@dwConnectionTypes,0);  
  end;

if InternetConnected=true then
    Edit1.Text:='your pc is Online now'
else
    begin
    Edit1.Text:='your pc is Offline now';
    form1.Close;
    end;