使用PHP和XMLReader解析XML

Question

我一直试图用PHP和XMLReader解析一个非常大的XML文件，但似乎无法得到我期待的结果。基本上，我正在搜索大量的信息，如果某个邮件包含某个邮政编码，我想返回那一点XML，或者继续搜索，直到找到该邮政编码。从本质上讲，我将把这个大文件分解成几个小块，所以不必查看数千或数百万个信息组，它可能是10或20个。

这里有一个位XML与想什么，我到

//search through xml 
<lineups country="USA"> 
//cache TX02217 as a variable 
<headend headendId="TX02217"> 
//cache Grande Gables at The Terrace as a variable 
    <name>Grande Gables at The Terrace</name> 
//cache Grande Communications as a variable 
    <mso msoId="17541">Grande Communications</mso> 
    <marketIds> 
    <marketId type="DMA">635</marketId> 
    </marketIds> 
//check to see if any of the postal codes are equal to $pc variable that will be set in the php 
    <postalCodes> 
    <postalCode>11111</postalCode> 
    <postalCode>22222</postalCode> 
    <postalCode>33333</postalCode> 
    <postalCode>78746</postalCode> 
    </postalCodes> 
//cache Austin to a variable 
    <location>Austin</location> 
    <lineup> 
//cache all prgSvcID's to an array i.e. 20014, 10722 
    <station prgSvcId="20014"> 
//cache all channels to an array i.e. 002, 003 
    <chan effDate="2006-01-16" tier="1">002</chan> 
    </station> 
    <station prgSvcId="10722"> 
    <chan effDate="2006-01-16" tier="1">003</chan> 
    </station> 
    </lineup> 
    <areasServed> 
    <area> 
//cache community to a variable $community 
    <community>Thorndale</community> 
    <county code="45331" size="D">Milam</county> 
//cache state to a variable i.e. TX 
    <state>TX</state> 
    </area> 
    <area> 
    <community>Thrall</community> 
    <county code="45491" size="B">Williamson</county> 
    <state>TX</state> 
    </area> 
    </areasServed> 
</headend> 

//if any of the postal codes matched $pc 
//echo back the xml from <headend> to </headend> 

//if none of the postal codes matched $pc 
//clear variables and move to next <headend> 

<headend> 
etc 
etc 
etc 
</headend> 
<headend> 
etc 
etc 
etc 
</headend> 
<headend> 
etc 
etc 
etc 
</headend> 
</lineups> 

PHP：

<?php 
$pc = "78746"; 
$xmlfile="myFile.xml"; 
$reader = new XMLReader(); 
$reader->open($xmlfile); 

while ($reader->read()) { 
//search to see if groups contain $pc and echo info 
} 

我知道我在做这个难度比它应该是，但我有点不知所措试图操纵这样一个大文件。任何帮助表示赞赏。

Answer 1

编辑：哦，你想返回父块？一会儿。

下面是一个将所有postalCodes拉出到数组中的例子。

http://codepad.org/kHss4MdV

<?php 

$string='<lineups country="USA"> 
<headend headendId="TX02217"> 
    <name>Grande Gables at The Terrace</name> 
    <mso msoId="17541">Grande Communications</mso> 
    <marketIds> 
    <marketId type="DMA">635</marketId> 
    </marketIds> 
    <postalCodes> 
    <postalCode>11111</postalCode> 
    <postalCode>22222</postalCode> 
    <postalCode>33333</postalCode> 
    <postalCode>78746</postalCode> 
    </postalCodes> 
    <location>Austin</location> 
    <lineup> 
    <station prgSvcId="20014"> 
    <chan effDate="2006-01-16" tier="1">002</chan> 
    </station> 
    <station prgSvcId="10722"> 
    <chan effDate="2006-01-16" tier="1">003</chan> 
    </station> 
    </lineup> 
    <areasServed> 
    <area> 
    <community>Thorndale</community> 
    <county code="45331" size="D">Milam</county> 
    <state>TX</state> 
    </area> 
    <area> 
    <community>Thrall</community> 
    <county code="45491" size="B">Williamson</county> 
    <state>TX</state> 
    </area> 
    </areasServed> 
</headend></lineups>'; 

$dom = new DOMDocument(); 
$dom->loadXML($string); 

$xpath = new DOMXPath($dom); 
$elements= $xpath->query('//lineups/headend/postalCodes/*[text()=78746]'); 

if (!is_null($elements)) { 
    foreach ($elements as $element) { 
    echo "<br/>[". $element->nodeName. "]"; 

    $nodes = $element->childNodes; 
    foreach ($nodes as $node) { 
     echo $node->nodeValue. "\n"; 
    } 
    } 
} 

输出：

<br/>[postalCode]78746 

Answer 2

为了获得更大的灵活性XMLReader我通常创建自己iterators that are able to work on the XMLReader object and provide the steps I need。

从对所有节点的简单迭代开始，直到迭代元素（可选地使用特定名称）。我们将最后一个XMLElementIterator称为读取器和元素名称作为参数。

在你的情况我然后将创建一个返回当前元素的SimpleXMLElement的迭代器，只服用了<headend>元素：

require('xmlreader-iterators.php'); // https://gist.github.com/hakre/5147685 

class HeadendIterator extends XMLElementIterator { 
    const ELEMENT_NAME = 'headend'; 

    public function __construct(XMLReader $reader) { 
     parent::__construct($reader, self::ELEMENT_NAME); 
    } 

    /** 
    * @return SimpleXMLElement 
    */ 
    public function current() { 
     return simplexml_load_string($this->reader->readOuterXml()); 
    } 
} 

配备该迭代作业的其余部分主要是小菜一碟。首先加载10千兆字节的文件：

$pc  = "78746"; 

$xmlfile = '../data/lineups.xml'; 
$reader = new XMLReader(); 
$reader->open($xmlfile); 

然后检查<headend>元素包含的信息，如果是的话，显示数据/ XML：

foreach (new HeadendIterator($reader) as $headend) { 
    /* @var $headend SimpleXMLElement */ 
    if (!$headend->xpath("/*/postalCodes/postalCode[. = '$pc']")) { 
     continue; 
    } 

    echo 'Found, name: ', $headend->name, "\n"; 
    echo "==========================================\n"; 
    $headend->asXML('php://stdout'); 
} 

这并不字面上你想实现：迭代大文档（这对内存友好），直到找到感兴趣的元素。然后处理具体元素，它只是XML; XMLReader::readOuterXml()在这里是一个很好的工具。

输出例：

Found, name: Grande Gables at The Terrace 
========================================== 
<?xml version="1.0"?> 
<headend headendId="TX02217"> 
     <name>Grande Gables at The Terrace</name> 
     <mso msoId="17541">Grande Communications</mso> 
     <marketIds> 
      <marketId type="DMA">635</marketId> 
     </marketIds> 
     <postalCodes> 
      <postalCode>11111</postalCode> 
      <postalCode>22222</postalCode> 
      <postalCode>33333</postalCode> 
      <postalCode>78746</postalCode> 
     </postalCodes> 
     <location>Austin</location> 
     <lineup> 
      <station prgSvcId="20014"> 
       <chan effDate="2006-01-16" tier="1">002</chan> 
      </station> 
      <station prgSvcId="10722"> 
       <chan effDate="2006-01-16" tier="1">003</chan> 
      </station> 
     </lineup> 
     <areasServed> 
      <area> 
       <community>Thorndale</community> 
       <county code="45331" size="D">Milam</county> 
       <state>TX</state> 
      </area> 
      <area> 
       <community>Thrall</community> 
       <county code="45491" size="B">Williamson</county> 
       <state>TX</state> 
      </area> 
     </areasServed> 
    </headend>