Php/docs/simplexml.examples-basic

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范例
Basic SimpleXML usage

Basic SimpleXML usage

Many examples in this reference require an XML string. Instead of repeating this string in every example, we put it into a file which we include in each example. This included file is shown in the following example section. Alternatively, you could create an XML document and read it with simplexml_load_file().

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 ActÓr</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>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;?>

以上例程会输出：

   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;?>

以上例程会输出：

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;}?>

以上例程会输出：

Ms. Coder played by Onlivia Actora
Mr. 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 indices case 'thumbs': echo $rating, ' thumbs up'; break; case 'stars': echo $rating, ' stars'; break; }}?>

以上例程会输出：

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);?>

以上例程会输出：

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?>

以上例程会输出：

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.

以上例程会输出：

Ms. Coder played by Onlivia Actora
Mr. 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();?>

以上例程会输出：

<?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();?>

以上例程会输出：

<?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;?>

以上例程会输出：

blah