防弹SimpleXMLElement [英] Bulletproofing SimpleXMLElement

问题描述

每个人都知道我们应该始终使用DOM技术而不是正则表达式来从HTML提取内容，但是我感到我永远都不相信SimpleXML扩展或类似的扩展。

Everyone knows that we should always use DOM techniques instead of regexes to extract content from HTML, but I get the feeling that I can never trust the SimpleXML extension or similar ones.

我现在正在编码一个OpenID实现，我尝试使用SimpleXML进行HTML发现-但是我的第一个测试（使用alixaxel.myopenid.com）产生了很多错误：

I'm coding a OpenID implementation right now, and I tried using SimpleXML to do the HTML discovery - but my very first test (with alixaxel.myopenid.com) yielded a lot of errors:

Warning: simplexml_load_string() [function.simplexml-load-string]: Entity: line 27: parser error : Opening and ending tag mismatch: link line 11 and head in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: </head> in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: ^ in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: Entity: line 64: parser error : Entity 'copy' not defined in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: &copy; 2008 <a href="http://janrain.com/">JanRain, Inc.</a> in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: ^ in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: Entity: line 66: parser error : Entity 'trade' not defined in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: myOpenID&trade; and the myOpenID&trade; website are in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: ^ in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: Entity: line 66: parser error : Entity 'trade' not defined in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: myOpenID&trade; and the myOpenID&trade; website are in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: ^ in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: Entity: line 77: parser error : Opening and ending tag mismatch: link line 8 and html in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: </html> in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: ^ in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: Entity: line 78: parser error : Premature end of data in tag head line 3 in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: ^ in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: Entity: line 78: parser error : Premature end of data in tag html line 2 in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: in E:\xampplite\htdocs\index.php on line 6

Warning: simplexml_load_string() [function.simplexml-load-string]: ^ in E:\xampplite\htdocs\index.php on line 6

我记得有一种方法可以使SimpleXML始终解析文件，无论文档是否包含错误都可以独立地进行解析-虽然我不记得具体的实现，但是我认为它涉及使用DOMDocument。确保SimpleXML始终解析任何给定文档的最佳方法是什么？

I recall there was a way to make SimpleXML always parse a file, independently if the document contains errors or not - I can't remember the specific implementation though, but I think it involved using DOMDocument. What is the best way to make sure SimpleXML always parses any given document?

而且请不要建议使用Tidy，我认为扩展速度很慢，并且无法使用许多系统。

And please don't suggest using Tidy, I think the extension is slow and it's not available on many systems.

推荐答案

您可以使用 DOM的loadHTML ，然后将结果导入到SimpleXML。

You can load the HTML with DOM's loadHTML then import the result to SimpleXML.

IIRC，它仍然会阻塞一些东西，但它会接受破碎网站现实世界中几乎所有存在的东西。

IIRC, it will still choke on some stuff but it will accept pretty much anything that exists in the real world of broken websites.

$html = '<html><head><body><div>stuff & stuff</body></html>';

// disable PHP errors
$old = libxml_use_internal_errors(true);

$dom = new DOMDocument;
$dom->loadHTML($html);

// restore the old behaviour
libxml_use_internal_errors($old);

$sxe = simplexml_import_dom($dom);
die($sxe->asXML());

这篇关于防弹SimpleXMLElement的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！