一、簡介及安裝

SimpleXML 擴(kuò)展提供了一個非常簡單和易于使用的工具集，能將 XML 轉(zhuǎn)換成一個帶有一般屬性選擇器和數(shù)組迭代器的對象。

此擴(kuò)展需要?libxml?PHP 擴(kuò)展。這表示需要使用?--enable-libxml?，盡管這將隱式完成因?yàn)?libxml 是缺省開啟的。

需要PHP5及以上版本。

此擴(kuò)展默認(rèn)為啟用,編譯時可通過下列選項(xiàng)禁用：?--disable-simplexml

二、使用示例基本使用

Example #1 Include file example.php with XML string

<?php$xmlstr?=?<<<XML<?xml?version=’1.0’?standalone=’yes’?><movies><movie><title>PHP:?Behind?the?Parser</title><characters><character><name>Ms.?Coder</name><actor>Onlivia?Actora</actor></character><character><name>Mr.?Coder</name><actor>El?Act&#211;r</actor></character></characters><plot>So,?this?language.?It’s?like,?a?programming?language.?Or?is?it?ascripting?language??All?is?revealed?in?this?thrilling?horror?spoofof?a?documentary.</plot><great-lines><line>PHP?solves?all?my?web?problems</line></great-lines><rating?type='thumbs'>7</rating><rating?type='stars'>5</rating></movie></movies>XML;?>

The simplicity of SimpleXML appears most clearly when one extracts a string or number from a basic XML document.

Example #2 Getting?<plot>

<?phpinclude?’example.php’;

$movies?=?new?SimpleXMLElement($xmlstr);

echo?$movies->movie[0]->plot;?>

以上例程會輸出：

So, this language. It’s like, a programming language. Or is it a scripting language? All is revealed in this thrilling horror spoof of a documentary.

Accessing elements within an XML document that contain characters not permitted under PHP’s naming convention (e.g. the hyphen) can be accomplished by encapsulating the element name within braces and the apostrophe.

Example #3 Getting?<line>

<?phpinclude?’example.php’;

$movies?=?new?SimpleXMLElement($xmlstr);

echo?$movies->movie->{’great-lines’}->line;?>

以上例程會輸出：

PHP solves all my web problems

Example #4 Accessing non-unique elements in SimpleXML

When multiple instances of an element exist as children of a single parent element, normal iteration techniques apply.

<?phpinclude?’example.php’;

$movies?=?new?SimpleXMLElement($xmlstr);

/*?For?each?<character>?node,?we?echo?a?separate?<name>.?*/foreach?($movies->movie->characters->character?as?$character)?{echo?$character->name,?’?played?by?’,?$character->actor,?PHP_EOL;}

?>

以上例程會輸出：

Ms. Coder played by Onlivia ActoraMr. Coder played by El Actór

Note:

Properties ($movies->movie?in previous example) are not arrays. They are?iterable?and?accessible?objects.

Example #5 Using attributes

So far, we have only covered the work of reading element names and their values. SimpleXML can also access element attributes. Access attributes of an element just as you would elements of an?array.

<?phpinclude?’example.php’;

$movies?=?new?SimpleXMLElement($xmlstr);

/*?Access?the?<rating>?nodes?of?the?first?movie.*?Output?the?rating?scale,?too.?*/foreach?($movies->movie[0]->rating?as?$rating)?{switch((string)?$rating[’type’])?{?//?Get?attributes?as?element?indicescase?’thumbs’:echo?$rating,?’?thumbs?up’;break;case?’stars’:echo?$rating,?’?stars’;break;}}?>

以上例程會輸出：

7 thumbs up5 stars

Example #6 Comparing Elements and Attributes with Text

To compare an element or attribute with a string or pass it into a function that requires a string, you must cast it to a string using?(string). Otherwise, PHP treats the element as an object.

<?phpinclude?’example.php’;

$movies?=?new?SimpleXMLElement($xmlstr);

if?((string)?$movies->movie->title?==?’PHP:?Behind?the?Parser’)?{print?’My?favorite?movie.’;}

echo?htmlentities((string)?$movies->movie->title);?>

以上例程會輸出：

My favorite movie.PHP: Behind the Parser

Example #7 Comparing Two Elements

Two SimpleXMLElements are considered different even if they point to the same element since PHP 5.2.0.

<?phpinclude?’example.php’;

$movies1?=?new?SimpleXMLElement($xmlstr);$movies2?=?new?SimpleXMLElement($xmlstr);var_dump($movies1?==?$movies2);?//?false?since?PHP?5.2.0?>

以上例程會輸出：

bool(false)

Example #8 Using XPath

SimpleXML includes built-in?XPath?support. To find all?<character>?elements:

<?phpinclude?’example.php’;

$movies?=?new?SimpleXMLElement($xmlstr);

foreach?($movies->xpath(’//character’)?as?$character)?{echo?$character->name,?’played?by?’,?$character->actor,?PHP_EOL;}?>

’//’ serves as a wildcard. To specify absolute paths, omit one of the slashes.

以上例程會輸出：

Ms. Coder played by Onlivia ActoraMr. Coder played by El Actór

Example #9 Setting values

Data in SimpleXML doesn’t have to be constant. The object allows for manipulation of all of its elements.

<?phpinclude?’example.php’;$movies?=?new?SimpleXMLElement($xmlstr);

$movies->movie[0]->characters->character[0]->name?=?’Miss?Coder’;

echo?$movies->asXML();?>

以上例程會輸出：

<?xml version='1.0' standalone='yes'?><movies> <movie> <title>PHP: Behind the Parser</title> <characters> <character> <name>Miss Coder</name> <actor>Onlivia Actora</actor> </character> <character> <name>Mr. Coder</name> <actor>El Act&#xD3;r</actor> </character> </characters> <plot> So, this language. It’s like, a programming language. Or is it a scripting language? All is revealed in this thrilling horror spoof of a documentary. </plot> <great-lines> <line>PHP solves all my web problems</line> </great-lines> <rating type='thumbs'>7</rating> <rating type='stars'>5</rating> </movie></movies>

Example #10 Adding elements and attributes

Since PHP 5.1.3, SimpleXML has had the ability to easily add children and attributes.

<?phpinclude?’example.php’;$movies?=?new?SimpleXMLElement($xmlstr);

$character?=?$movies->movie[0]->characters->addChild(’character’);$character->addChild(’name’,?’Mr.?Parser’);$character->addChild(’actor’,?’John?Doe’);

$rating?=?$movies->movie[0]->addChild(’rating’,?’PG’);$rating->addAttribute(’type’,?’mpaa’);

echo?$movies->asXML();?>

以上例程會輸出：

<?xml version='1.0' standalone='yes'?><movies> <movie> <title>PHP: Behind the Parser</title> <characters> <character> <name>Ms. Coder</name> <actor>Onlivia Actora</actor> </character> <character> <name>Mr. Coder</name> <actor>El Act&#xD3;r</actor> </character> <character><name>Mr. Parser</name><actor>John Doe</actor></character></characters> <plot> So, this language. It’s like, a programming language. Or is it a scripting language? All is revealed in this thrilling horror spoof of a documentary. </plot> <great-lines> <line>PHP solves all my web problems</line> </great-lines> <rating type='thumbs'>7</rating> <rating type='stars'>5</rating> <rating type='mpaa'>PG</rating></movie></movies>

Example #11 DOM Interoperability

PHP has a mechanism to convert XML nodes between SimpleXML and DOM formats. This example shows how one might change a DOM element to SimpleXML.

<?php$dom?=?new?DOMDocument;$dom->loadXML(’<books><book><title>blah</title></book></books>’);if?(!$dom)?{echo?’Error?while?parsing?the?document’;exit;}

$books?=?simplexml_import_dom($dom);

echo?$books->book[0]->title;?>

以上例程會輸出：

blah處理XML錯誤

Example #1 Loading broken XML string

<?phplibxml_use_internal_errors(true);$sxe?=?simplexml_load_string('<?xml?version=’1.0’><broken><xml></broken>');if?($sxe?===?false)?{echo?'Failed?loading?XMLn';foreach(libxml_get_errors()?as?$error)?{echo?'t',?$error->message;}}?>

以上例程會輸出：

Failed loading XML Blank needed here parsing XML declaration: ’?>’ expected Opening and ending tag mismatch: xml line 1 and broken Premature end of data in tag broken line 1三、相關(guān)函數(shù)simplexml_import_dom?— Get a SimpleXMLElement object from a DOM node.simplexml_load_file?— Interprets an XML file into an objectsimplexml_load_string?— Interprets a string of XML into an object四、相關(guān)類及成員函數(shù)

SimpleXMLElement類

SimpleXMLElement::addAttribute?— Adds an attribute to the SimpleXML elementSimpleXMLElement::addChild?— Adds a child element to the XML nodeSimpleXMLElement::asXML?— Return a well-formed XML string based on SimpleXML elementSimpleXMLElement::attributes?— Identifies an element’s attributesSimpleXMLElement::children?— Finds children of given nodeSimpleXMLElement::__construct?— Creates a new SimpleXMLElement objectSimpleXMLElement::count?— Counts the children of an elementSimpleXMLElement::getDocNamespaces?— Returns namespaces declared in documentSimpleXMLElement::getName?— Gets the name of the XML elementSimpleXMLElement::getNamespaces?— Returns namespaces used in documentSimpleXMLElement::registerXPathNamespace?— Creates a prefix/ns context for the next XPath querySimpleXMLElement::saveXML?— 別名 SimpleXMLElement::asXMLSimpleXMLElement::__toString?— Returns the string contentSimpleXMLElement::xpath?— Runs XPath query on XML data

SimpleXMLIterator類

SimpleXMLIterator::current?— Returns the current elementSimpleXMLIterator::getChildren?— Returns the sub-elements of the current elementSimpleXMLIterator::hasChildren?— Checks whether the current element has sub elements.SimpleXMLIterator::key?— Return current keySimpleXMLIterator::next?— Move to next elementSimpleXMLIterator::rewind?— Rewind to the first elementSimpleXMLIterator::valid?— Check whether the current element is valid