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delphi中检查URL是否存在的函数

2007-07-04 14:20 281 查看

检查一个 URL 是否有效函数

//检查一个URL是否有效函数:function CheckUrl(url: string): Boolean;

//可用来检测网络连接是否正确，InternetCheckConnection函数检查不准确，有些情况无法检测到，而以下CheckUrl函数则不会。
//uses wininet;
function CheckUrl(url: string): Boolean;
var
hSession, hfile, hRequest: hInternet;
dwindex, dwcodelen: dword;
dwcode: array[1..20] of Char;
res: PChar;
begin
Result := false;
if Pos(’http://’, LowerCase(url)) = 0 then url := ’http://’ + url;
hSession := InternetOpen(’InetURL:/1.0’, INTERNET_OPEN_TYPE_PRECONFIG,
nil, nil, 0);
if Assigned(hsession) then
begin
hfile := InternetOpenUrl(hsession, PChar(url), nil, 0, INTERNET_FLAG_RELOAD, 0);
dwIndex := 0;
dwCodeLen := 10;
HttpQueryInfo(hfile, HTTP_QUERY_STATUS_CODE, @dwcode, dwcodeLen, dwIndex);
res := PChar(@dwcode);
Result := (res = ’200’) or (res = ’302’); //200,302未重定位标志
if Assigned(hfile) then
InternetCloseHandle(hfile);
InternetCloseHandle(hsession);
end;
end;

//方法二：

function CheckUrl(url: string; TimeOut: integer = 5000): boolean;
var
hSession, hfile, hRequest: hInternet;
dwindex, dwcodelen: dword;
dwcode: array[1..20] of char;
res: pchar;
re: integer;
Err1: integer;
j: integer;
begin
if pos(’http://’, lowercase(url)) = 0 then
url := ’http://’ + url;
Result := false;
InternetSetOption(hSession, Internet_OPTION_CONNECT_TIMEOUT, @TimeOut, 4);
hSession := InternetOpen(’Mozilla/4.0’, INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
//设置超时
if assigned(hsession) then
begin
j := 1;
while true do
begin
hfile := InternetOpenUrl(hsession, pchar(url), nil, 0, INTERNET_FLAG_RELOAD, 0);
if hfile = nil then
begin
j := j + 1;
Err1 := GetLastError;
if j 〉 5 then break;
if (Err1 〈〉 12002) or (Err1 〈〉 12152) then break;
sleep(2);
end
else begin
break;
end;
end;
dwIndex := 0;
dwCodeLen := 10;
HttpQueryInfo(hfile, HTTP_QUERY_STATUS_CODE, @dwcode, dwcodeLen, dwIndex);
res := pchar(@dwcode);
re := strtointdef(res, 404);
case re of
400..450: result := false;
else result := true;
end;
if assigned(hfile) then
InternetCloseHandle(hfile);
InternetCloseHandle(hsession);
end;
end;

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