解析XML与PHP和XMLReader的(Parse XML with PHP and XMLRea

我一直在试图解析PHP和XMLReader的一个非常大的XML文件，但似乎无法让我期待的结果。基本上，我在寻找一吨的信息，如果一个含有一定邮编，我想返回XML的该位，或继续寻找，直到找到邮政编码。从本质上讲，我会分解成只有几小块打破这个大文件，这样就不必再次看成千上万的信息组，这将是也许10的或者20的。

这里有一个位的XML与想什么，我要

//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么大的文件。任何帮助表示赞赏。

Answer 1:

为了获得更灵活XMLReader我通常自己创造那些能够在上工作迭代器XMLReader对象，并提供我所需要的步骤。

这用一个简单的迭代所有节点开始到迭代上任选一个特定名称的元素。让我们把最后一个XMLElementIterator考虑读者和元素名作为参数。

在你的情况我再会创建一个返回的迭代器SimpleXMLElement当前元素，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);

然后检查是否<headend>元素中包含的信息，如果是，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');
}

这确实从字面上你想要什么来实现：遍历大的文档（这是记忆型），直到找到元素（S）你有兴趣，您再处理具体的元素，并将其唯一的XML。 XMLReader::readOuterXml()在这里是不错的工具。

典型的输出：

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>

Answer 2:

编辑：哦，你想回到父块？一个瞬间。

下面是使出浑身postalCodes成一个阵列的例子。

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：