使用PHP和XMLReader解析XML

Question

我一直試圖用PHP和XMLReader解析一個非常大的XML文件，但似乎無法得到我期待的結果。基本上，我正在搜索大量的信息，如果某個郵件包含某個郵政編碼，我想返回那一點XML，或者繼續搜索，直到找到該郵政編碼。從本質上講，我將把這個大文件分解成幾個小塊，所以不必查看數千或數百萬個信息組，它可能是10或20個。

這裏有一個位XML與想什麼，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 
} 

我知道我在做這個難度比它應該是，但我有點不知所措試圖操縱這樣一個大文件。任何幫助表示讚賞。

Answer 1

編輯：哦，你想返回父塊？一會兒。

下面是一個將所有postalCodes拉出到數組中的例子。

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"; 
    } 
    } 
} 

輸出：

<br/>[postalCode]78746 

Answer 2

爲了獲得更大的靈活性XMLReader我通常創建自己iterators that are able to work on the XMLReader object and provide the steps I need。

從對所有節點的簡單迭代開始，直到迭代元素（可選地使用特定名稱）。我們將最後一個XMLElementIterator稱爲讀取器和元素名稱作爲參數。

在你的情況我然後將創建一個返回當前元素的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()); 
    } 
} 

配備該迭代作業的其餘部分主要是小菜一碟。首先加載10千兆字節的文件：

$pc  = "78746"; 

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

然後檢查<headend>元素包含的信息，如果是的話，顯示數據/ 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'); 
} 

這並不字面上你想實現：迭代大文檔（這對內存友好），直到找到感興趣的元素。然後處理具體元素，它只是XML; XMLReader::readOuterXml()在這裏是一個很好的工具。

輸出例：

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>