使用PHP和XMLReader解析XML [英] Parse XML with PHP and XMLReader
问题描述
我一直在尝试使用PHP和XMLReader解析一个非常大的XML文件，但是似乎无法获得我想要的结果.基本上，我正在搜索大量信息，并且如果其中包含某个邮政编码，我想返回那一部分XML，或者继续搜索直到找到该邮政编码.本质上，我将把这个大文件分成几个小块，因此不必查看成千上万的信息组，它可能是10或20.
I've been trying to parse a very large XML file with PHP and XMLReader, but can't seem to get the results I am looking for. Basically, I'm searching a ton of information, and if a contains a certain zipcode, I'd like to return that bit of XML, or keep searching until it finds that zipcode. Essentially, I'll be breaking this big file down into only a few small chunks, so instead of having to look at thousands or millions of groups of information, it would be maybe 10's or 20's.
这里有一些我想要的XML
Here's a bit of the XML with what I'd like to
//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
}
我知道我正在使它比应有的难度更大，但是尝试操纵如此大的文件有点不知所措.感谢您的帮助.
I know I'm making this harder than it should be but am a little overwhelmed trying to manipulate such a large file. Any help is appreciated.
推荐答案
To gain more flexibility with XMLReader I normally create myself 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，到可选地使用特定名称的元素上的迭代开始.我们以阅读器和元素名称作为参数，称为最后一个XMLElementIterator.
That starts with a simple iteration over all nodes over to the iteration over elements optionally with a specific name. Let's call the last one XMLElementIterator taking the reader and the element name as parameters.
然后在您的场景中，我将创建一个迭代器，该迭代器为当前元素返回一个SimpleXMLElement，仅使用<headend>元素:
In your scenario I then would create an iterator that returns a SimpleXMLElement for the current element, taking only the <headend> elements:
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());
}
}
配备了该迭代器后，剩下的工作主要是小菜一碟.首先加载10 GB的文件:
Equipped with this iterator the rest of your job is mainly a piece of cake. First load the 10 gigabyte file:
$pc = "78746";
$xmlfile = '../data/lineups.xml';
$reader = new XMLReader();
$reader->open($xmlfile);
然后检查<headend>元素是否包含信息，如果包含，则显示数据/XML:
And then check if the <headend> element contains the information and if so, display the data / 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');
}
这确实符合您要实现的目标:遍历大型文档(对内存友好)，直到找到您感兴趣的元素.然后处理具体元素及其XML只要; XMLReader::readOuterXml() 在这里是很好的工具.
This does literally what you're trying to achieve: Iterate over the large document (which is memory-friendly) until you find the element(s) you're interested in. You then process on the concrete element and it's XML only; XMLReader::readOuterXml() is a fine tool here.
示例性输出:
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>
这篇关于使用PHP和XMLReader解析XML的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
