SimpleXMLElement::__construct
(PHP 5 >= 5.0.1)
SimpleXMLElement::__construct — Creates a new SimpleXMLElement object
说明
$data
[, int $options = 0
[, bool $data_is_url = false
[, string $ns = ""
[, bool $is_prefix = false
]]]] )Creates a new SimpleXMLElement object.
参数
-
data -
A well-formed XML string or the path or URL to an XML document if
data_is_urlisTRUE. -
options -
Optionally used to specify additional Libxml parameters.
-
data_is_url -
By default,
data_is_urlisFALSE. UseTRUEto specify thatdatais a path or URL to an XML document instead of string data. -
ns -
Namespace prefix or URI.
-
is_prefix -
TRUEifnsis a prefix,FALSEif it's a URI; defaults toFALSE.
返回值
Returns a SimpleXMLElement object representing
data.
错误／异常
Produces an E_WARNING error message for each error
found in the XML data and additionally throws an Exception if the XML data
could not be parsed.
Use libxml_use_internal_errors() to suppress all XML errors, and libxml_get_errors() to iterate over them afterwards.
范例
Note:
Listed examples may include example.php, which refers to the XML string found in the first example of the basic usage guide.
Example #1 Create a SimpleXMLElement object
<?php
include 'example.php' ;
$sxe = new SimpleXMLElement ( $xmlstr );
echo $sxe -> movie [ 0 ]-> title ;
?> 以上例程会输出：
PHP: Behind the Parser
Example #2 Create a SimpleXMLElement object from a URL
<?php
$sxe = new SimpleXMLElement ( 'http://example.org/document.xml' , NULL , TRUE );
echo $sxe -> asXML ();
?> 更新日志
| 版本 | 说明 |
|---|---|
| 5.2.0 | Added the ns and is_prefix parameters. |
| 5.1.2 | Added the options and data_is_url parameters. |
参见
- Basic SimpleXML usage
- simplexml_load_string() - Interprets a string of XML into an object
- simplexml_load_file() - Interprets an XML file into an object
- Dealing with XML errors
- libxml_use_internal_errors() - Disable libxml errors and allow user to fetch error information as needed
用户评论:
[#1] Phil Cross [2014-09-01 11:39:42]
It's worth noting, that you need to typecast dynamic property names to string in order to retrieve there value, for example:
<?php
$xml = new SimpleXMLElement('records.xml', 0, true);
// This will work as expected because its a hard coded property value
foreach($xml as $record){
echo $record->id; // Will output the ID fine
}
// Dynamic properties require typecasting to string
$xml_field = 'id';
foreach($xml as $record){
// This will dump a SimpleXMLElement object
var_dump($record->$xml_field);
// This will output the value as expected
echo (string)$record->$xml_field;
}
?>
[#2] bertolini dot cedric at me dot com [2014-06-16 11:07:33]
It's worth noting that the behavior of SimpleXmlElement::__construct is not exactly the same as simplexml_load_string, regarding libxml_use_internal_errors().
In my case,
<?php
libxml_use_internal_errors(true);
new \SimpleXmlElement($data);
?>
was still throwing error. But as soon as I switched to
<?php
libxml_use_internal_errors(true);
simplexml_load_string($data);
?>
everything worked fine and I stopped getting an error.
[#3] kumarldh at gmail dot com [2011-03-22 22:50:21]
Using libxml_use_internal_errors() may suppress errors but Exception still requires decent handling. I used following code snippet.
<?php
libxml_use_internal_errors(true);
try{
$xmlToObject = new SimpleXMLElement($notSoWellFormedXML);
} catch (Exception $e){
echo 'Please try again later...';
exit();
}
?>
[#4] uramihsayibok, gmail, com [2009-08-16 18:52:58]
As I was filling out a bug report, I realized why (speculation here) the constructor is final: so that functions like simplexml_load_file and simplexml_load_string can work. I imagine the PHP-ized code looks something like
<?php
function simplexml_load_file($filename, $class_name = "SimpleXMLElement", $options = 0, $ns = "", $is_prefix = false) {
return new $class_name($filename, $options, true, $ns, $is_prefix);
}
?>
If we were to use a different $class_name and change the constructor's definition these functions wouldn't work.
There's no easy, sensible solution that keeps simplexml_load_file and simplexml_load_string.
[#5] tudor at culise dot net [2007-11-20 03:35:02]
This class is extendable, but it's too bad that its constructor cannot be overriden (PHP says it's a final method). Thus the class should be wrapped using the delegation principle rather that extended.