怎样确定网络是否连通？(想听听大家是怎么做的） (100分)

我用ADOCONNECTION和ADOQUERY连接局域网上的另一台机器（服务器）上的SQL SEVER数据库，
ADOCONNECTIONSTRING是事先指定好的，ADOCONNCTION的CONNECTED属性默认为FALSE,程序运行时
我用一个按钮控制ADOCONNECTION的CONNECTED属性，在网络接通的情况下，下面一段代码运行
没有问题：
procedure TForm1.button1.click(sender:Tobject);
begin
try
adoconnection1.connected:=true;
except
messagedlg('网络不通！',mtwarning,[mbok],0);
end;
end;
我们单位的网络经常不通，在网络不通时，运行这段程序就死机（try后面这句过不去）

请问我用什么办法可以知道网络是否连通？

gz

关注

先设置 TAdoConnection 的连接超时：ConnectionTimeout。

设为15，但不管用

何不用 IdICMP 来 Ping 一下，通了再连啊。

检测计算机是否联网比较简单的做法可以通过一个 Win32 Internet(WinInet) 函数
InternetQueryOption 来实现
以下是一个判断当前计算机是否可以获得 Internet 服务的例子：

function TForm1.CheckOffline: boolean;

var

ConnectState: DWORD;

StateSize: DWORD;

begin

ConnectState:= 0;

StateSize:= SizeOf(ConnectState);

result:= false;

if InternetQueryOption(nil, INTERNET_OPTION_CONNECTED_STATE, @ConnectState, StateSize) then

if (ConnectState and INTERNET_STATE_DISCONNECTED) <> 2 then result:= true;

end;

procedure TForm1.Button1Click(Sender: TObject);

begin

if CheckOffline then

edit1.text:= 'Connect To ISP'

else

edit1.text:= 'Disconnect To ISP';

end;

设置 AdoConnection 的ConnectionTimeout
在AdoConnection的AfterDisconnect事件中加入代码
adoconnection1.connected:=true;
??:= '网络已中断，正在重新连接';
...
想办法排除网络故障

1.搂住的过程再我的机器成不死机，执行正常
2。AdoConnection的AfterDisconnect事件，在连接失败后 无法触发
3。触发AdoConnection的BeforeConnect时间
procedure TForm1.ADOConnection1BeforeConnect(Sender: TObject);
begin
messagedlg('22网络不通！',mtwarning,[mbok],0);
end;

delphi5 + win2k(英文)

还是先PING一下好，也不麻烦，在程序中可以这样实现：做个FORM，在主程序界面上加
个BUTTON或菜单项调用这个FORM(我平时的做法)，完整代码如下：
interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls,winsock, ExtCtrls;

type
PIPOptionInformation = ^TIPOptionInformation;
TIPOptionInformation=packed record
TTL: Byte;
TOS: Byte;
Flags: Byte;
OptionsSize: Byte;
OptionsData: PChar;
end;
PIcmpEchoReply = ^TIcmpEchoReply;
TIcmpEchoReply = packed record
Address: DWORD;
Status: DWORD;
RTT: DWORD;
DataSize:Word;
Reserved: Word;
Data: Pointer;
Options: TIPOptionInformation;
end;
TIcmpCreateFile = function: THandle; stdcall;
TIcmpCloseHandle = function(IcmpHandle: THandle): Boolean; stdcall;
TIcmpSendEcho =
function(IcmpHandle:THandle;
DestinationAddressWORD;
RequestData: Pointer;
RequestSize: Word;
RequestOptions: PIPOptionInformation;
ReplyBuffer: Pointer;
ReplySize: DWord;
Timeout: DWord )Word; stdcall;
TFtest = class(TForm)
Memo1: TMemo;
Timer1: TTimer;
procedure FormCreate(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
procedure Timer1Timer(Sender: TObject);

private
{ Private declarations }
hICMP: THANDLE;
IcmpCreateFile : TIcmpCreateFile;
IcmpCloseHandle:TIcmpCloseHandle;
IcmpSendEcho: TIcmpSendEcho;
public
{ Public declarations }
WSAData:TWSAData;
end;

var
Ftest: TFtest;
i:integer;
implementation

{$R *.dfm}
uses main;
procedure TFtest.FormCreate(Sender: TObject);
var hiCMPdll:HMODULE;

{ IPOpt:TIPOptionInformation;
FIPAddressWORD;
pReqData,pRevDataChar;
pIPEIcmpEchoReply;
FSize: DWORD;
MyString:string;
FTimeOutWORD;
BufferSizeWORD; }
begin
i:=0;
WSAStartup(2,WSAData);
hICMPdll := LoadLibrary('icmp.dll');
@ICMPCreateFile := GetProcAddress(hICMPdll, 'IcmpCreateFile');
@IcmpCloseHandle := GetProcAddress(hICMPdll, 'IcmpCloseHandle');
@IcmpSendEcho := GetProcAddress(hICMPdll, 'IcmpSendEcho');
hICMP :=IcmpCreateFile;
memo1.Text:='';
memo1.Lines.Add('数据中心连接测试信息:');

{FIPAddress:=inet_addr(pchar('127.0.0.1'));
FSize := 40;
BufferSize := SizeOf(TICMPEchoReply) + FSize;
GetMem(pRevData,FSize);
GetMem(pIPE,BufferSize);
FillChar(pIPE^, SizeOf(pIPE^), 0);
pIPE^.Data := pRevData;
MyString := '-------Hello,World!---------------';
pReqData := PChar(MyString);
FillChar(IPOpt, Sizeof(IPOpt), 0);
IPOpt.TTL := 64;
ftimeout:=4000;
IcmpSendEcho(hICMP, FIPAddress, pReqData, Length(MyString),
@IPOpt, pIPE, BufferSize, FTimeOut);
try
try
if pReqData^ = pIPE^.Options.OptionsData^ then
begin
memo1.Lines.Add(PChar('127.0.0.1') + '-----'
+IntToStr(pIPE^.DataSize) + '-----' +IntToStr(pIPE^.RTT));
end;
except

memo1.Text:='';
memo1.Lines.Add('数据中心连接失败！请检查一下您的网络连接！');
end;
finally
FreeMem(pRevData);
FreeMem(pIPE);
end; }
end;

procedure TFtest.FormClose(Sender: TObject; var Action: TCloseAction);
begin
wsacleanup();
Action:=caFree;
end;

procedure TFtest.Timer1Timer(Sender: TObject);
var
IPOpt:TIPOptionInformation;
FIPAddressWORD;
pReqData,pRevDataChar;
pIPEIcmpEchoReply;
FSize: DWORD;
MyString:string;
FTimeOutWORD;
BufferSizeWORD;

begin
i:=i+1;
FIPAddress:=inet_addr(pchar('127.0.0.1'));
FSize := 40;
BufferSize := SizeOf(TICMPEchoReply) + FSize;
GetMem(pRevData,FSize);
GetMem(pIPE,BufferSize);
FillChar(pIPE^, SizeOf(pIPE^), 0);
pIPE^.Data := pRevData;
MyString := '-------Hello,World!---------------';
pReqData := PChar(MyString);
FillChar(IPOpt, Sizeof(IPOpt), 0);
IPOpt.TTL := 64;
ftimeout:=4000;
IcmpSendEcho(hICMP, FIPAddress, pReqData, Length(MyString),
@IPOpt, pIPE, BufferSize, FTimeOut);
try
try
if pReqData^ = pIPE^.Options.OptionsData^ then
begin
memo1.Lines.Add(' '+PChar(inttostr(i)+' '+'连接数据中心') + ' ----- 发送信息（字节）：'
+IntToStr(pIPE^.DataSize) + ' ----- 返回时间（毫秒）：' +IntToStr(pIPE^.RTT)+' ----- TTL:'+inttostr(pipe^.options.ttl));

end;
except

//memo1.Text:='';
memo1.Lines.Add(' 数据中心连接失败！请检查一下您的网络连接！');
memo1.Lines.Add(' '+PChar(inttostr(i)+' '+'连接数据中心') + ' ----- 发送信息（字节）：'
+IntToStr(pIPE^.DataSize) + ' ----- 返回时间（毫秒）：' +IntToStr(pIPE^.RTT)+' ----- TTL:'+inttostr(pipe^.options.ttl));

end;
finally
FreeMem(pRevData);
FreeMem(pIPE);
end;
end;

end.

procedure TForm1.button1.click(sender:Tobject);
begin
try
adoconnection1.open
finally
if adoconnection1.connected:=true then
begin
............
end
else
messagedlg('网络不通！',mtwarning,[mbok],0);
end;
end;
这样不会死机

楼上的代码不行啊，死的很难看。

继续关注！

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ICS控件包里有一个Ping控件，首先Ping一下， 通了以后，再连接数据库。