如何检查给定的字符串是否是有效的URL地址?
我对正则表达式的知识是基本的，不允许我从我已经在网上看到的数百个正则表达式中进行选择。
当前回答
下面的正则表达式适用于我:
(http(s)?:\/\/.)?(ftp(s)?:\/\/.)?(www\.)?[-a-zA-Z0-9@:%._\+~#=]{0,256}\.[a-z]
{2,6}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)
匹配:
https://google.com t.me https://t.me ftp://google.com http://sm.tj http://bro.tj t.me/rshss https:google.com www.cool.com.au http://www.cool.com.au http://www.cool.com.au/ersdfs http://www.cool.com.au/ersdfs?dfd=dfgd@s=1 http://www.cool.com:81/index.html
其他回答
关于眼睑问题，他的回答是“这是基于我对URI规范的阅读。”谢谢眼睑，你的是我寻求的完美的解决方案，因为它是基于URI规范!出色的工作。：）
我不得不做了两个修改。第一个在PHP (v5.2.10)中使用preg_match()函数使regexp正确匹配IP地址url的方法。
我不得不在管道周围的“IP Address”上方的行中添加一组括号:
)|((\d|[1-9]\d|1\d{2}|2[0-4][0-9]|25[0-5])\.){3}(?#
不知道为什么。
我还将顶级域名的最小长度从3个字母减少到2个字母，以支持.co。英国和类似国家。
最后的代码:
/^(https?|ftp):\/\/(?# protocol
)(([a-z0-9$_\.\+!\*\'\(\),;\?&=-]|%[0-9a-f]{2})+(?# username
)(:([a-z0-9$_\.\+!\*\'\(\),;\?&=-]|%[0-9a-f]{2})+)?(?# password
)@)?(?# auth requires @
)((([a-z0-9]\.|[a-z0-9][a-z0-9-]*[a-z0-9]\.)*(?# domain segments AND
)[a-z][a-z0-9-]*[a-z0-9](?# top level domain OR
)|((\d|[1-9]\d|1\d{2}|2[0-4][0-9]|25[0-5])\.){3}(?#
)(\d|[1-9]\d|1\d{2}|2[0-4][0-9]|25[0-5])(?# IP address
))(:\d+)?(?# port
))(((\/+([a-z0-9$_\.\+!\*\'\(\),;:@&=-]|%[0-9a-f]{2})*)*(?# path
)(\?([a-z0-9$_\.\+!\*\'\(\),;:@&=-]|%[0-9a-f]{2})*)(?# query string
)?)?)?(?# path and query string optional
)(#([a-z0-9$_\.\+!\*\'\(\),;:@&=-]|%[0-9a-f]{2})*)?(?# fragment
)$/i
这个修改后的版本没有根据URI规范进行检查，所以我不能保证它的合规性，它被修改为处理本地网络环境中的URL和两位tld以及其他类型的Web URL，并在我使用的PHP设置中更好地工作。
作为PHP代码:
define('URL_FORMAT',
'/^(https?):\/\/'. // protocol
'(([a-z0-9$_\.\+!\*\'\(\),;\?&=-]|%[0-9a-f]{2})+'. // username
'(:([a-z0-9$_\.\+!\*\'\(\),;\?&=-]|%[0-9a-f]{2})+)?'. // password
'@)?(?#'. // auth requires @
')((([a-z0-9]\.|[a-z0-9][a-z0-9-]*[a-z0-9]\.)*'. // domain segments AND
'[a-z][a-z0-9-]*[a-z0-9]'. // top level domain OR
'|((\d|[1-9]\d|1\d{2}|2[0-4][0-9]|25[0-5])\.){3}'.
'(\d|[1-9]\d|1\d{2}|2[0-4][0-9]|25[0-5])'. // IP address
')(:\d+)?'. // port
')(((\/+([a-z0-9$_\.\+!\*\'\(\),;:@&=-]|%[0-9a-f]{2})*)*'. // path
'(\?([a-z0-9$_\.\+!\*\'\(\),;:@&=-]|%[0-9a-f]{2})*)'. // query string
'?)?)?'. // path and query string optional
'(#([a-z0-9$_\.\+!\*\'\(\),;:@&=-]|%[0-9a-f]{2})*)?'. // fragment
'$/i');
下面是一个PHP测试程序，它使用正则表达式验证各种url:
<?php
define('URL_FORMAT',
'/^(https?):\/\/'. // protocol
'(([a-z0-9$_\.\+!\*\'\(\),;\?&=-]|%[0-9a-f]{2})+'. // username
'(:([a-z0-9$_\.\+!\*\'\(\),;\?&=-]|%[0-9a-f]{2})+)?'. // password
'@)?(?#'. // auth requires @
')((([a-z0-9]\.|[a-z0-9][a-z0-9-]*[a-z0-9]\.)*'. // domain segments AND
'[a-z][a-z0-9-]*[a-z0-9]'. // top level domain OR
'|((\d|[1-9]\d|1\d{2}|2[0-4][0-9]|25[0-5])\.){3}'.
'(\d|[1-9]\d|1\d{2}|2[0-4][0-9]|25[0-5])'. // IP address
')(:\d+)?'. // port
')(((\/+([a-z0-9$_\.\+!\*\'\(\),;:@&=-]|%[0-9a-f]{2})*)*'. // path
'(\?([a-z0-9$_\.\+!\*\'\(\),;:@&=-]|%[0-9a-f]{2})*)'. // query string
'?)?)?'. // path and query string optional
'(#([a-z0-9$_\.\+!\*\'\(\),;:@&=-]|%[0-9a-f]{2})*)?'. // fragment
'$/i');
/**
* Verify the syntax of the given URL.
*
* @access public
* @param $url The URL to verify.
* @return boolean
*/
function is_valid_url($url) {
if (str_starts_with(strtolower($url), 'http://localhost')) {
return true;
}
return preg_match(URL_FORMAT, $url);
}
/**
* String starts with something
*
* This function will return true only if input string starts with
* niddle
*
* @param string $string Input string
* @param string $niddle Needle string
* @return boolean
*/
function str_starts_with($string, $niddle) {
return substr($string, 0, strlen($niddle)) == $niddle;
}
/**
* Test a URL for validity and count results.
* @param url url
* @param expected expected result (true or false)
*/
$numtests = 0;
$passed = 0;
function test_url($url, $expected) {
global $numtests, $passed;
$numtests++;
$valid = is_valid_url($url);
echo "URL Valid?: " . ($valid?"yes":"no") . " for URL: $url. Expected: ".($expected?"yes":"no").". ";
if($valid == $expected) {
echo "PASS\n"; $passed++;
} else {
echo "FAIL\n";
}
}
echo "URL Tests:\n\n";
test_url("http://localserver/projects/public/assets/javascript/widgets/UserBoxMenu/widget.css", true);
test_url("http://www.google.com", true);
test_url("http://www.google.co.uk/projects/my%20folder/test.php", true);
test_url("https://myserver.localdomain", true);
test_url("http://192.168.1.120/projects/index.php", true);
test_url("http://192.168.1.1/projects/index.php", true);
test_url("http://projectpier-server.localdomain/projects/public/assets/javascript/widgets/UserBoxMenu/widget.css", true);
test_url("https://2.4.168.19/project-pier?c=test&a=b", true);
test_url("https://localhost/a/b/c/test.php?c=controller&arg1=20&arg2=20", true);
test_url("http://user:password@localhost/a/b/c/test.php?c=controller&arg1=20&arg2=20", true);
echo "\n$passed out of $numtests tests passed.\n\n";
?>
再次感谢regex的虚实!
我一直在写一篇深入的文章，讨论使用正则表达式进行URI验证。它基于RFC3986。
正则表达式URI验证
虽然这篇文章还不完整，但我已经提出了一个PHP函数，它在验证HTTP和FTP url方面做得非常好。以下是当前版本:
// function url_valid($url) { Rev:20110423_2000
//
// Return associative array of valid URI components, or FALSE if $url is not
// RFC-3986 compliant. If the passed URL begins with: "www." or "ftp.", then
// "http://" or "ftp://" is prepended and the corrected full-url is stored in
// the return array with a key name "url". This value should be used by the caller.
//
// Return value: FALSE if $url is not valid, otherwise array of URI components:
// e.g.
// Given: "http://www.jmrware.com:80/articles?height=10&width=75#fragone"
// Array(
// [scheme] => http
// [authority] => www.jmrware.com:80
// [userinfo] =>
// [host] => www.jmrware.com
// [IP_literal] =>
// [IPV6address] =>
// [ls32] =>
// [IPvFuture] =>
// [IPv4address] =>
// [regname] => www.jmrware.com
// [port] => 80
// [path_abempty] => /articles
// [query] => height=10&width=75
// [fragment] => fragone
// [url] => http://www.jmrware.com:80/articles?height=10&width=75#fragone
// )
function url_valid($url) {
if (strpos($url, 'www.') === 0) $url = 'http://'. $url;
if (strpos($url, 'ftp.') === 0) $url = 'ftp://'. $url;
if (!preg_match('/# Valid absolute URI having a non-empty, valid DNS host.
^
(?P<scheme>[A-Za-z][A-Za-z0-9+\-.]*):\/\/
(?P<authority>
(?:(?P<userinfo>(?:[A-Za-z0-9\-._~!$&\'()*+,;=:]|%[0-9A-Fa-f]{2})*)@)?
(?P<host>
(?P<IP_literal>
\[
(?:
(?P<IPV6address>
(?: (?:[0-9A-Fa-f]{1,4}:){6}
| ::(?:[0-9A-Fa-f]{1,4}:){5}
| (?: [0-9A-Fa-f]{1,4})?::(?:[0-9A-Fa-f]{1,4}:){4}
| (?:(?:[0-9A-Fa-f]{1,4}:){0,1}[0-9A-Fa-f]{1,4})?::(?:[0-9A-Fa-f]{1,4}:){3}
| (?:(?:[0-9A-Fa-f]{1,4}:){0,2}[0-9A-Fa-f]{1,4})?::(?:[0-9A-Fa-f]{1,4}:){2}
| (?:(?:[0-9A-Fa-f]{1,4}:){0,3}[0-9A-Fa-f]{1,4})?:: [0-9A-Fa-f]{1,4}:
| (?:(?:[0-9A-Fa-f]{1,4}:){0,4}[0-9A-Fa-f]{1,4})?::
)
(?P<ls32>[0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}
| (?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}
(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)
)
| (?:(?:[0-9A-Fa-f]{1,4}:){0,5}[0-9A-Fa-f]{1,4})?:: [0-9A-Fa-f]{1,4}
| (?:(?:[0-9A-Fa-f]{1,4}:){0,6}[0-9A-Fa-f]{1,4})?::
)
| (?P<IPvFuture>[Vv][0-9A-Fa-f]+\.[A-Za-z0-9\-._~!$&\'()*+,;=:]+)
)
\]
)
| (?P<IPv4address>(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}
(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))
| (?P<regname>(?:[A-Za-z0-9\-._~!$&\'()*+,;=]|%[0-9A-Fa-f]{2})+)
)
(?::(?P<port>[0-9]*))?
)
(?P<path_abempty>(?:\/(?:[A-Za-z0-9\-._~!$&\'()*+,;=:@]|%[0-9A-Fa-f]{2})*)*)
(?:\?(?P<query> (?:[A-Za-z0-9\-._~!$&\'()*+,;=:@\\/?]|%[0-9A-Fa-f]{2})*))?
(?:\#(?P<fragment> (?:[A-Za-z0-9\-._~!$&\'()*+,;=:@\\/?]|%[0-9A-Fa-f]{2})*))?
$
/mx', $url, $m)) return FALSE;
switch ($m['scheme']) {
case 'https':
case 'http':
if ($m['userinfo']) return FALSE; // HTTP scheme does not allow userinfo.
break;
case 'ftps':
case 'ftp':
break;
default:
return FALSE; // Unrecognized URI scheme. Default to FALSE.
}
// Validate host name conforms to DNS "dot-separated-parts".
if ($m['regname']) { // If host regname specified, check for DNS conformance.
if (!preg_match('/# HTTP DNS host name.
^ # Anchor to beginning of string.
(?!.{256}) # Overall host length is less than 256 chars.
(?: # Group dot separated host part alternatives.
[A-Za-z0-9]\. # Either a single alphanum followed by dot
| # or... part has more than one char (63 chars max).
[A-Za-z0-9] # Part first char is alphanum (no dash).
[A-Za-z0-9\-]{0,61} # Internal chars are alphanum plus dash.
[A-Za-z0-9] # Part last char is alphanum (no dash).
\. # Each part followed by literal dot.
)* # Zero or more parts before top level domain.
(?: # Explicitly specify top level domains.
com|edu|gov|int|mil|net|org|biz|
info|name|pro|aero|coop|museum|
asia|cat|jobs|mobi|tel|travel|
[A-Za-z]{2}) # Country codes are exactly two alpha chars.
\.? # Top level domain can end in a dot.
$ # Anchor to end of string.
/ix', $m['host'])) return FALSE;
}
$m['url'] = $url;
for ($i = 0; isset($m[$i]); ++$i) unset($m[$i]);
return $m; // return TRUE == array of useful named $matches plus the valid $url.
}
这个函数使用了两个正则表达式;一个用于匹配有效通用uri的子集(具有非空主机的绝对uri)，另一个用于验证DNS“点分隔部分”主机名。虽然这个函数目前只验证HTTP和FTP方案，但它的结构使它可以很容易地扩展以处理其他方案。
下面的RegEx可以工作:
"@((((ht)|(f))tp[s]?://)|(www\.))([a-z][-a-z0-9]+\.)?([a-z][-a-z0-9]+\.)?[a-z][-a-z0-9]+\.[a-z]+[/]?[a-z0-9._\/~#&=;%+?-]*@si"
如果你真的在搜索终极匹配，你可能会在“一个好的Url正则表达式?”
但是，一个真正匹配所有可能域并允许rfc允许的任何内容的正则表达式是可怕的长且不可读的，相信我;-)
有趣的是，上面的答案都不能满足我的需要，所以我想我可以提供我的解决方案。我需要做到以下几点:
匹配http(s)://www.google.com, http://google.com, www.google.com和google.com 匹配Github降价风格的链接，如[谷歌](http://www.google.com) 匹配所有可能的域名扩展名，比如。com，或。io，或。guru等。基本上长度在2-6个字符之间 将所有内容分成适当的组，以便我可以根据需要访问每个部分。
解决办法是这样的:
/^(\[[A-z0-9 _]*\]\()?((?:(http|https):\/\/)?(?:[\w-]+\.)+[a-z]{2,6})(\))?$
这就满足了上述所有要求。如果需要，你可以选择添加ftp和file功能:
/^(\[[A-z0-9 _]*\]\()?((?:(http|https|ftp|file):\/\/)?(?:[\w-]+\.)+[a-z]{2,6})(\))?$
