使用正则表达式验证Youtube URL

问题描述

我正在尝试验证我的应用程序的YouTube网址.

I'm trying to validate YouTube URLs for my application.

到目前为止，我有以下内容:

So far I have the following:

// Set the youtube URL
$youtube_url = "www.youtube.com/watch?v=vpfzjcCzdtCk";

if (preg_match("/((http\:\/\/){0,}(www\.){0,}(youtube\.com){1} || (youtu\.be){1}(\/watch\?v\=[^\s]){1})/", $youtube_url) == 1)
{
    echo "Valid";
else
{
    echo "Invalid";
}

我希望验证Youtube Urls的以下变体:

I wish to validate the following variations of Youtube Urls:

• 有无http://
• 带有和不带有www.
• 使用网址youtube.com和youtu.be
• 必须有/watch?v =
• 必须具有唯一的视频字符串(在上面的示例"vp​​fzjcCzdtCk"中)

但是，我认为我的逻辑不正确，因为出于某种原因，它为以下内容返回 true :(请注意，我用.co和不是.com)

However, I don't think I've got my logic right, because for some reason it returns true for: www.youtube.co/watch?v=vpfzjcCzdtCk (Notice I've written it incorrectly with .co and not .com)

推荐答案

您的正则表达式中有很多冗余(而且倾斜的牙签综合征).不过，这应该会产生结果:

There are a lot of redundancies in this regular expression of yours (and also, the leaning toothpick syndrome). This, though, should produce results:

$rx = '~
  ^(?:https?://)?                           # Optional protocol
   (?:www[.])?                              # Optional sub-domain
   (?:youtube[.]com/watch[?]v=|youtu[.]be/) # Mandatory domain name (w/ query string in .com)
   ([^&]{11})                               # Video id of 11 characters as capture group 1
    ~x';

$has_match = preg_match($rx, $url, $matches);

// if matching succeeded, $matches[1] would contain the video ID

一些注意事项:

• 使用波浪号~作为分隔符，以避免LTS
• 使用[.]而不是\.来提高视觉清晰度并避免LTS. (特殊"字符(例如点.-在字符类中不起作用(在方括号中))
• 要使正则表达式更具可读性"，可以使用x修饰符(具有进一步的含义；请参见有关模式修饰符的文档)，该文档还允许在正则表达式中添加注释
• 可以使用非捕获组(c8)来抑制捕获.这样可以使表达更有效.

• use the tilde character ~ as delimiter, to avoid LTS
• use [.] instead of \. to improve visual legibility and avoid LTS. ("Special" characters - such as the dot . - have no effect in character classes (within square brackets))
• to make regular expressions more "readable" you can use the x modifier (which has further implications; see the docs on Pattern modifiers), which also allows for comments in regular expressions
• capturing can be suppressed using non-capturing groups: (?: <pattern> ). This makes the expression more efficient.

(可选)要从(或多或少完整的)URL中提取值，您可能要使用 parse_url() :

Optionally, to extract values from a (more or less complete) URL, you might want to make use of parse_url():

$url = 'http://youtube.com/watch?v=VIDEOID';
$parts = parse_url($url);
print_r($parts);

输出:

Array
(
    [scheme] => http
    [host] => youtube.com
    [path] => /watch
    [query] => v=VIDEOID
)

验证域名和提取视频ID留给读者练习.

Validating the domain name and extracting the video ID is left as an exercise to the reader.

我屈服于下面的评论之战；多亏了Toni Oriol，正则表达式现在也可以在短(youtu.be)URL上使用.

I gave in to the comment war below; thanks to Toni Oriol, the regular expression now works on short (youtu.be) URLs as well.

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