XMLREADER/DOM/SIMPLEXML 解析大文件

DOM和simplexml处理xml非常的灵活方便，它们的内存组织结构与xml文件格式很相近。但是同时它们也有一个缺点，对于大文件处理起来力不从心，太耗内存了。

还好有xmlreader，基于流的解析器，（什么是基于流）。它可以对于xml大文件进行解析，采用一边读取一边解析的方法，而不是一股脑儿都加载到内存去处理。但是它也有缺点，不够灵活方便（这是DOM和simplexml擅长的）。

那些把他们结合起来，不就可以很好的解析大文件了吗？我写了一个简单的类实现了一点点鸡肋般的功能。

xml文件

<?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>
<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>

实现类

class SimpleXmlReader extends XMLReader{

    public function __construct($source, $isfile = false){

        if($isfile){

            $this->open($source);

        }else{

            $this->XML($source);

        }

    }

    public function getElement($nodename, $depth = 0){

        if($this->localName == $nodename && $this->nodeType == self::ELEMENT){

            if(!$depth || ($depth && $depth == $this->depth)){

                $this->next();

            }

        }

        while($this->read()){

            if($this->localName == $nodename && $this->nodeType == self::ELEMENT){

                if(!$depth || ($depth && $depth == $this->depth)){

                    return true;

                }

            }

        }

        return false;

    }

    public function expandNodeToSimpleXml(){

       if($this->nodeType == self::ELEMENT){

           $node = $this->expand();

           $dom = new DomDocument();

           $n = $dom->importNode($node, true);

           $sxe = simplexml_import_dom($n);

           return $sxe;

       }

       return false;

    }

}

实例代码：

$xmlhl = new SimpleXmlReader('test.xml', true);

while($xmlhl->getElement('movie')){

    $sxe = $xmlhl->expandNodeToSimpleXml();

    foreach($sxe->characters[0] as $character){

        echo "\n name -> "  . $character->name;

        echo "\n actor -> " . $character->actor;

    }

}

结构：

 name -> Ms. Coder

 actor -> Onlivia Actora

 name -> Mr. Coder

 actor -> El ActÓr

 name -> Ms. Coder

 actor -> Onlivia Actora

 name -> Mr. Coder

 actor -> El ActÓr

巴特西

XMLREADER/DOM/SIMPLEXML 解析大文件

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