如何在PHP中检查URL是否存在(而不是404)？
这里:
$file = 'http://www.domain.com/somefile.jpg';
$file_headers = @get_headers($file);
if(!$file_headers || $file_headers[0] == 'HTTP/1.1 404 Not Found') {
$exists = false;
}
else {
$exists = true;
}
从这里和上面的帖子正下方,有一个卷曲解决方案:
function url_exists($url) {
if (!$fp = curl_init($url)) return false;
return true;
}
在确定php中是否存在url时,有几点需要注意:
url本身是否有效(字符串,不是空的,良好的语法),这很快检查服务器端.
等待响应可能需要时间并阻止代码执行.
并非get_headers()返回的所有头文件都是格式良好的.
使用卷曲(如果可以).
防止获取整个正文/内容,但仅请求标题.
考虑重定向网址:
你想要第一个代码返回吗？
或者按照所有重定向并返回最后一个代码？
您可能最终得到200,但它可以使用元标记或javascript重定向.弄清楚之后会发生什么是艰难的.
请记住,无论您使用何种方法,都需要时间等待响应.
所有代码可能(并且可能会)停止,直到您知道结果或请求已超时.
例如:如果网址无效或无法访问,则以下代码可能需要很长时间才能显示该网页:
$url){
// this could potentially take 0-30 seconds each
// (more or less depending on connection, target site, timeout settings...)
if( ! isValidUrl($url) ){
unset($urls[$k]);
}
}
echo "yay all done! now show my site";
foreach($urls as $url){
echo "{$url}
";
}
以下功能可能会有所帮助,您可能需要修改它们以满足您的需求:
function isValidUrl($url){
// first do some quick sanity checks:
if(!$url || !is_string($url)){
return false;
}
// quick check url is roughly a valid http request: ( http://blah/... )
if( ! preg_match('/^http(s)?:\/\/[a-z0-9-]+(\.[a-z0-9-]+)*(:[0-9]+)?(\/.*)?$/i', $url) ){
return false;
}
// the next bit could be slow:
if(getHttpResponseCode_using_curl($url) != 200){
// if(getHttpResponseCode_using_getheaders($url) != 200){ // use this one if you cant use curl
return false;
}
// all good!
return true;
}
function getHttpResponseCode_using_curl($url, $followredirects = true){
// returns int responsecode, or false (if url does not exist or connection timeout occurs)
// NOTE: could potentially take up to 0-30 seconds , blocking further code execution (more or less depending on connection, target site, and local timeout settings))
// if $followredirects == false: return the FIRST known httpcode (ignore redirects)
// if $followredirects == true : return the LAST known httpcode (when redirected)
if(! $url || ! is_string($url)){
return false;
}
$ch = @curl_init($url);
if($ch === false){
return false;
}
@curl_setopt($ch, CURLOPT_HEADER ,true); // we want headers
@curl_setopt($ch, CURLOPT_NOBODY ,true); // dont need body
@curl_setopt($ch, CURLOPT_RETURNTRANSFER ,true); // catch output (do NOT print!)
if($followredirects){
@curl_setopt($ch, CURLOPT_FOLLOWLOCATION ,true);
@curl_setopt($ch, CURLOPT_MAXREDIRS ,10); // fairly random number, but could prevent unwanted endless redirects with followlocation=true
}else{
@curl_setopt($ch, CURLOPT_FOLLOWLOCATION ,false);
}
// @curl_setopt($ch, CURLOPT_CONNECTTIMEOUT ,5); // fairly random number (seconds)... but could prevent waiting forever to get a result
// @curl_setopt($ch, CURLOPT_TIMEOUT ,6); // fairly random number (seconds)... but could prevent waiting forever to get a result
// @curl_setopt($ch, CURLOPT_USERAGENT ,"Mozilla/5.0 (Windows NT 6.0) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1"); // pretend we're a regular browser
@curl_exec($ch);
if(@curl_errno($ch)){ // should be 0
@curl_close($ch);
return false;
}
$code = @curl_getinfo($ch, CURLINFO_HTTP_CODE); // note: php.net documentation shows this returns a string, but really it returns an int
@curl_close($ch);
return $code;
}
function getHttpResponseCode_using_getheaders($url, $followredirects = true){
// returns string responsecode, or false if no responsecode found in headers (or url does not exist)
// NOTE: could potentially take up to 0-30 seconds , blocking further code execution (more or less depending on connection, target site, and local timeout settings))
// if $followredirects == false: return the FIRST known httpcode (ignore redirects)
// if $followredirects == true : return the LAST known httpcode (when redirected)
if(! $url || ! is_string($url)){
return false;
}
$headers = @get_headers($url);
if($headers && is_array($headers)){
if($followredirects){
// we want the the last errorcode, reverse array so we start at the end:
$headers = array_reverse($headers);
}
foreach($headers as $hline){
// search for things like "HTTP/1.1 200 OK" , "HTTP/1.0 200 OK" , "HTTP/1.1 301 PERMANENTLY MOVED" , "HTTP/1.1 400 Not Found" , etc.
// note that the exact syntax/version/output differs, so there is some string magic involved here
if(preg_match('/^HTTP\/\S+\s+([1-9][0-9][0-9])\s+.*/', $hline, $matches) ){// "HTTP/*** ### ***"
$code = $matches[1];
return $code;
}
}
// no HTTP/xxx found in headers:
return false;
}
// no headers :
return false;
}
$headers = @get_headers($this->_value); if(strpos($headers[0],'200')===false)return false;
所以,只要你联系一个网站并得到200以上的其他东西就可以了
你不能在某些服务器上使用curl你可以使用这个代码
$url = 'http://google.com'; $not_url = 'stp://google.com'; if (@file_get_contents($url)): echo "Found '$url'!"; else: echo "Can't find '$url'."; endif; if (@file_get_contents($not_url)): echo "Found '$not_url!"; else: echo "Can't find '$not_url'."; endif; // Found 'http://google.com'!Can't find 'stp://google.com'.
function URLIsValid($URL)
{
$exists = true;
$file_headers = @get_headers($URL);
$InvalidHeaders = array('404', '403', '500');
foreach($InvalidHeaders as $HeaderVal)
{
if(strstr($file_headers[0], $HeaderVal))
{
$exists = false;
break;
}
}
return $exists;
}
我用这个函数:
/**
* @param $url
* @param array $options
* @return string
* @throws Exception
*/
function checkURL($url, array $options = array()) {
if (empty($url)) {
throw new Exception('URL is empty');
}
// list of HTTP status codes
$httpStatusCodes = array(
100 => 'Continue',
101 => 'Switching Protocols',
102 => 'Processing',
200 => 'OK',
201 => 'Created',
202 => 'Accepted',
203 => 'Non-Authoritative Information',
204 => 'No Content',
205 => 'Reset Content',
206 => 'Partial Content',
207 => 'Multi-Status',
208 => 'Already Reported',
226 => 'IM Used',
300 => 'Multiple Choices',
301 => 'Moved Permanently',
302 => 'Found',
303 => 'See Other',
304 => 'Not Modified',
305 => 'Use Proxy',
306 => 'Switch Proxy',
307 => 'Temporary Redirect',
308 => 'Permanent Redirect',
400 => 'Bad Request',
401 => 'Unauthorized',
402 => 'Payment Required',
403 => 'Forbidden',
404 => 'Not Found',
405 => 'Method Not Allowed',
406 => 'Not Acceptable',
407 => 'Proxy Authentication Required',
408 => 'Request Timeout',
409 => 'Conflict',
410 => 'Gone',
411 => 'Length Required',
412 => 'Precondition Failed',
413 => 'Payload Too Large',
414 => 'Request-URI Too Long',
415 => 'Unsupported Media Type',
416 => 'Requested Range Not Satisfiable',
417 => 'Expectation Failed',
418 => 'I\'m a teapot',
422 => 'Unprocessable Entity',
423 => 'Locked',
424 => 'Failed Dependency',
425 => 'Unordered Collection',
426 => 'Upgrade Required',
428 => 'Precondition Required',
429 => 'Too Many Requests',
431 => 'Request Header Fields Too Large',
449 => 'Retry With',
450 => 'Blocked by Windows Parental Controls',
500 => 'Internal Server Error',
501 => 'Not Implemented',
502 => 'Bad Gateway',
503 => 'Service Unavailable',
504 => 'Gateway Timeout',
505 => 'HTTP Version Not Supported',
506 => 'Variant Also Negotiates',
507 => 'Insufficient Storage',
508 => 'Loop Detected',
509 => 'Bandwidth Limit Exceeded',
510 => 'Not Extended',
511 => 'Network Authentication Required',
599 => 'Network Connect Timeout Error'
);
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_NOBODY, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
if (isset($options['timeout'])) {
$timeout = (int) $options['timeout'];
curl_setopt($ch, CURLOPT_TIMEOUT, $timeout);
}
curl_exec($ch);
$returnedStatusCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
if (array_key_exists($returnedStatusCode, $httpStatusCodes)) {
return "URL: '{$url}' - Error code: {$returnedStatusCode} - Definition: {$httpStatusCodes[$returnedStatusCode]}";
} else {
return "'{$url}' does not exist";
}
}
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