我如何检查一个URL是否存在(不是404)在PHP?
当前回答
cURL可以返回HTTP代码，我不认为所有额外的代码是必要的?
function urlExists($url=NULL)
{
if($url == NULL) return false;
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_TIMEOUT, 5);
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 5);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$data = curl_exec($ch);
$httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
if($httpcode>=200 && $httpcode<300){
return true;
} else {
return false;
}
}
其他回答
当从php中判断url是否存在时，有几件事需要注意:
Is the url itself valid (a string, not empty, good syntax), this is quick to check server side. Waiting for a response might take time and block code execution. Not all headers returned by get_headers() are well formed. Use curl (if you can). Prevent fetching the entire body/content, but only request the headers. Consider redirecting urls: Do you want the first code returned? Or follow all redirects and return the last code? You might end up with a 200, but it could redirect using meta tags or javascript. Figuring out what happens after is tough.
请记住，无论你使用什么方法，等待回复都需要时间。 所有代码都可能(很可能)停止，直到您知道结果或请求超时。
例如:如果url无效或不可达，下面的代码可能需要很长时间才能显示页面:
<?php
$urls = getUrls(); // some function getting say 10 or more external links
foreach($urls as $k=>$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 $url){
echo "<a href=\"{$url}\">{$url}</a><br/>";
}
下面的函数可能会有帮助，你可能想修改它们以适应你的需要:
function isValidUrl($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 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;
}
$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 '$not_url'.";
endif;
// Found 'http://google.com'!Can't find 'stp://google.com'.
检查URL是否有效的其他方法可以是:
<?php
if (isValidURL("http://www.gimepix.com")) {
echo "URL is valid...";
} else {
echo "URL is not valid...";
}
function isValidURL($url) {
$file_headers = @get_headers($url);
if (strpos($file_headers[0], "200 OK") > 0) {
return true;
} else {
return false;
}
}
?>
function URLIsValid($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;
}
karim79的get_headers()解决方案并没有为我工作，因为我得到了疯狂的结果与Pinterest。
get_headers(): SSL operation failed with code 1. OpenSSL Error messages: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed
Array
(
[url] => https://www.pinterest.com/jonathan_parl/
[exists] =>
)
get_headers(): Failed to enable crypto
Array
(
[url] => https://www.pinterest.com/jonathan_parl/
[exists] =>
)
get_headers(https://www.pinterest.com/jonathan_parl/): failed to open stream: operation failed
Array
(
[url] => https://www.pinterest.com/jonathan_parl/
[exists] =>
)
不管怎样，这个开发人员演示了cURL比get_headers()快得多:
http://php.net/manual/fr/function.get-headers.php#104723
由于许多人要求karim79修复的是cURL解决方案，这里是我今天构建的解决方案。
/**
* Send an HTTP request to a the $url and check the header posted back.
*
* @param $url String url to which we must send the request.
* @param $failCodeList Int array list of code for which the page is considered invalid.
*
* @return Boolean
*/
public static function isUrlExists($url, array $failCodeList = array(404)){
$exists = false;
if(!StringManager::stringStartWith($url, "http") and !StringManager::stringStartWith($url, "ftp")){
$url = "https://" . $url;
}
if (preg_match(RegularExpression::URL, $url)){
$handle = curl_init($url);
curl_setopt($handle, CURLOPT_RETURNTRANSFER, true);
curl_setopt($handle, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($handle, CURLOPT_HEADER, true);
curl_setopt($handle, CURLOPT_NOBODY, true);
curl_setopt($handle, CURLOPT_USERAGENT, true);
$headers = curl_exec($handle);
curl_close($handle);
if (empty($failCodeList) or !is_array($failCodeList)){
$failCodeList = array(404);
}
if (!empty($headers)){
$exists = true;
$headers = explode(PHP_EOL, $headers);
foreach($failCodeList as $code){
if (is_numeric($code) and strpos($headers[0], strval($code)) !== false){
$exists = false;
break;
}
}
}
}
return $exists;
}
让我来解释一下旋度选项:
CURLOPT_RETURNTRANSFER:返回一个字符串，而不是在屏幕上显示调用页面。
CURLOPT_SSL_VERIFYPEER: cUrl不会签出证书
CURLOPT_HEADER:在字符串中包含头文件
CURLOPT_NOBODY:不要在字符串中包含body
CURLOPT_USERAGENT:一些站点需要它才能正常运行(例如:https://plus.google.com)
附加说明:在这个函数中，我使用Diego Perini的正则表达式在发送请求之前验证URL:
const URL = "%^(?:(?:https?|ftp)://)(?:\S+(?::\S*)?@|\d{1,3}(?:\.\d{1,3}){3}|(?:(?:[a-z\d\x{00a1}-\x{ffff}]+-?)*[a-z\d\x{00a1}-\x{ffff}]+)(?:\.(?:[a-z\d\x{00a1}-\x{ffff}]+-?)*[a-z\d\x{00a1}-\x{ffff}]+)*(?:\.[a-z\x{00a1}-\x{ffff}]{2,6}))(?::\d+)?(?:[^\s]*)?$%iu"; //@copyright Diego Perini
附加说明2:我将标题字符串和用户标题[0]分开，以确保只验证返回代码和消息(例如:200、404、405等)。
附加说明3:有时仅验证代码404是不够的(参见单元测试)，因此有一个可选的$failCodeList参数提供所有要拒绝的代码列表。
当然，这里还有单元测试(包括所有流行的社交网络)来证明我的代码是合法的:
public function testIsUrlExists(){
//invalid
$this->assertFalse(ToolManager::isUrlExists("woot"));
$this->assertFalse(ToolManager::isUrlExists("https://www.facebook.com/jonathan.parentlevesque4545646456"));
$this->assertFalse(ToolManager::isUrlExists("https://plus.google.com/+JonathanParentL%C3%A9vesque890800"));
$this->assertFalse(ToolManager::isUrlExists("https://instagram.com/mariloubiz1232132/", array(404, 405)));
$this->assertFalse(ToolManager::isUrlExists("https://www.pinterest.com/jonathan_parl1231/"));
$this->assertFalse(ToolManager::isUrlExists("https://regex101.com/546465465456"));
$this->assertFalse(ToolManager::isUrlExists("https://twitter.com/arcadefire4566546"));
$this->assertFalse(ToolManager::isUrlExists("https://vimeo.com/**($%?%$", array(400, 405)));
$this->assertFalse(ToolManager::isUrlExists("https://www.youtube.com/user/Darkjo666456456456"));
//valid
$this->assertTrue(ToolManager::isUrlExists("www.google.ca"));
$this->assertTrue(ToolManager::isUrlExists("https://www.facebook.com/jonathan.parentlevesque"));
$this->assertTrue(ToolManager::isUrlExists("https://plus.google.com/+JonathanParentL%C3%A9vesque"));
$this->assertTrue(ToolManager::isUrlExists("https://instagram.com/mariloubiz/"));
$this->assertTrue(ToolManager::isUrlExists("https://www.facebook.com/jonathan.parentlevesque"));
$this->assertTrue(ToolManager::isUrlExists("https://www.pinterest.com/"));
$this->assertTrue(ToolManager::isUrlExists("https://regex101.com"));
$this->assertTrue(ToolManager::isUrlExists("https://twitter.com/arcadefire"));
$this->assertTrue(ToolManager::isUrlExists("https://vimeo.com/"));
$this->assertTrue(ToolManager::isUrlExists("https://www.youtube.com/user/Darkjo666"));
}
祝大家取得巨大成功，
Jonathan Parent-Lévesque在蒙特利尔报道
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