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(PHP 5, PHP 7)
DOMDocument::loadXML — Load XML from a string
$source
[, int $options
= 0
] )Loads an XML document from a string.
source
The string containing the XML.
options
Bitwise OR of the libxml option constants.
成功时返回 TRUE
, 或者在失败时返回 FALSE
。 If called statically, returns a
DOMDocument 或者在失败时返回 FALSE
.
If an empty string is passed as the source
,
a warning will be generated. This warning is not generated by libxml
and cannot be handled using libxml's error handling functions.
此方法可以被静态调用,但会抛出一个 E_STRICT
错误。
Example #1 Creating a Document
<?php
$doc = new DOMDocument ();
$doc -> loadXML ( '<root><node/></root>' );
echo $doc -> saveXML ();
?>
Example #2 Static invocation of loadXML
<?php
// Issues an E_STRICT error
$doc = DOMDocument :: loadXML ( '<root><node/></root>' );
echo $doc -> saveXML ();
?>
[#1] Gustavo L. Fabro [2013-11-14 16:41:38]
Always remember that with the default parameters this function doesn't handle well large files, i.e. if a text node is longer than 10Mb it can raise an exception stating:
DOMDocument::loadXML(): internal error Extra content at the end of the document in Entity
even though the XML is fine.
The cause is a definition in parserInternals.h of lixml:
#define XML_MAX_TEXT_LENGTH 10000000
To allow the function to process larger files, pass the LIBXML_PARSEHUGE as an option and it will work just fine:
$domDocument->loadXML($xml, LIBXML_PARSEHUGE);
[#2] szalma dot laszlo at zengo dot eu [2009-10-27 08:14:27]
Loading from a string works fine without the
<?phpxml version="1.0" encoding="utf-8"?>
header, but in this case the xmlEncoding won't be set, and this makes the utf-8 characters (international, and special characters) to be encoded as hexa entities when saved with saveXML()!
[#3] remacg [2009-02-26 07:33:20]
Instead of doing this:
<?php
$str = <<<XML
<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE root [
<!ENTITY nbsp " ">
]>
<div>This is a non-breaking space.</div>
XML;
$dd2 = new DOMDocument();
$dd2->loadXML($str);
echo $dd2->saveXML();
?>
simply use:
loadHTML() rather than loadXML().
[#4] olalonde at NOSPAM dot gmail dot com [2008-03-21 17:00:32]
For some reason, when you set DOMDocument's property 'recover' to true, using '@' to mask errors thrown by loadXml() won't work.
Here's my workaround:
function maskErrors() {}
set_error_handler('maskErrors');
$dom->loadXml($xml);
restore_error_handler();
You could also simply do this: error_reporting(0); and then set back error_reporting to its original state.
[#5] Stuart Grimshaw [2007-06-26 13:57:27]
Possible values for the options parameter can be found here:
http://us3.php.net/manual/en/ref.libxml.php#libxml.constants
[#6] Marc Liyanage [2007-06-18 07:08:43]
The documentation states that loadXML can be called statically, but this is misleading. This feature seems to be a special case hack and its use seems to be discouraged according to http://bugs.php.net/bug.php?id=41398.
Calling the method statically will fail with an error if the code runs with E_STRICT error reporting enabled.
The documentation should be changed to make it clear that a static call is against recommended practice and won't work with E_STRICT.
[#7] jazzslider at hotmail dot com [2007-04-30 13:14:11]
When using loadXML() to parse a string that contains entity references (e.g., ), be sure that those entity references are properly declared through the use of a DOCTYPE declaration; otherwise, loadXML() will not be able to interpret the string.
Example:
<?php
$str = <<<XML
<?xml version="1.0" encoding="iso-8859-1"?>
<div>This is a non-breaking space.</div>
XML;
$dd1 = new DOMDocument();
$dd1->loadXML($str);
echo $dd1->saveXML();
?>
Given the above code, PHP will issue a Warning about the entity 'nbsp' not being properly declared. Also, the call to saveXML() will return nothing but a trimmed-down version of the original processing instruction...everything else is gone, and all because of the undeclared entity.
Instead, explicitly declare the entity first:
<?php
$str = <<<XML
<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE root [
<!ENTITY nbsp " ">
]>
<div>This is a non-breaking space.</div>
XML;
$dd2 = new DOMDocument();
$dd2->loadXML($str);
echo $dd2->saveXML();
?>
Since the 'nbsp' entity is defined in the DOCTYPE, PHP no longer issues that Warning; the string is now well-formed, and loadXML() understands it perfectly.
You can also use references to external DTDs in the same way (e.g., <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">), which is particularly important if you need to do this for many different documents with many different possible entities.
Also, as a sidenote...entity references created by createEntityReference() do not need this kind of explicit declaration.
[#8] shaoyu73 at gmail dot com [2007-03-15 20:53:58]
earth at anonymous dot com,
preserveWhiteSpace property needs to be set to false for formatOutput to work properly, for some reason.
$dom = new DOMDocument;
$dom->preserveWhiteSpace = false;
$dom->loadXML($xmlStr);
...
$element->appendChild(...);
...
$dom->formatOutput = true;
$xmlStr = $dom->saveXML();
echo $xmlStr;
This would format the output nicely.
[#9] Gavin Sinai gsinai at gmx dot net [2006-08-30 07:34:39]
loadXml reports an error instead of throwing an exception when the xml is not well formed. This is annoying if you are trying to to loadXml() in a try...catch statement. Apparently its a feature, not a bug, because this conforms to a spefication.
If you want to catch an exception instead of generating a report, you could do something like
<?php
function HandleXmlError($errno, $errstr, $errfile, $errline)
{
if ($errno==E_WARNING && (substr_count($errstr,"DOMDocument::loadXML()")>0))
{
throw new DOMException($errstr);
}
else
return false;
}
function XmlLoader($strXml)
{
set_error_handler('HandleXmlError');
$dom = new DOMDocument();
$dom->loadXml($strXml);
restore_error_handler();
return $dom;
}
?>
Returning false in function HandleXmlError() causes a fallback to the default error handler.
[#10] mp at webfactory dot de [2006-08-08 08:26:54]
While loadXML() expects its input to have a leading XML processing instruction to deduce the encoding used, there's no such concept in (non-XML) HTML documents. Thus, the libxml library underlying the DOM functions peeks at the <META> tags to figure out the encoding used.
See http://xmlsoft.org/encoding.html.
[#11] earth at anonymous dot com [2006-04-12 02:28:44]
Note that loadXML crops off beginning and trailing whitespace and linebreaks.
When using loadXML and appendChild to add a chunk of XML to an existing document, you may want to force a linebreak between the end of the XML chunk and the next line (usually a close tag) in the output file:
$childDocument = new DOMDocument;
$childDocument>preserveWhiteSpace = true;
$childDocument->loadXML(..XML-Chunk..);
$mNewNode = $mainDOcument->importNode($childDocument->documentElement, true);
$ParentNode->appendChild($mNewNode);
$ParentNode->appendChild($mainDocument->createTextNode("\\n ");
Although it is said that DOM should not be used to make 'pretty' XML output, it is something I struggled with to get something that was readable for testing. Another solution is to use the createDocumentFragment()->appendXML(..XML-Chunk..) instead, which seems not to trim off linebreaks like DOMDocument->loadXML() does.