如何使用xpath从xml中找到基于属性值的元素值？

Question

这是文件(1.xml)

<?xml version="1.0" encoding="UTF-8"?>
<traceCollecFile xmlns="http://www.3gpp.org/ftp/specs/archive/32_series/32.423#traceData" >
<fileHeader fileFormatVersion="32.423 V10.0" vendorName="CDOT GROUP" >
<fileSender elementDn="DC=a1.companycdot.com,SubNetwork=1, ManagedElement=MME-1_1_1" elementType="MME" />
</fileHeader>
<traceRecSession dnPrefix="DC=a1.companycdot.com,SubNetwork=1" traceRecSessionRef="992" stime="2018-06-08T13:47:12-05:30" >
<ue idType="IMSI" idValue="311480000002255" />
<msg function="S6" name="UPDATE LOCATION ANSWER" changeTime="0.000000" vendorSpecific="false" >
<ie name="RESULT_CODE">2001</ie>
</msg>
<traceSessionRef >
<MCC>311</MCC>
<MNC>480</MNC>
<TRACE_ID>8323073</TRACE_ID>
</traceSessionRef>
</traceRecSession>
<traceRecSession dnPrefix="DC=a1.companycdot.com,SubNetwork=1" traceRecSessionRef="992" stime="2018-06-08T13:47:12-05:30" >
<ue idType="IMSI" idValue="311480000002255" />
<msg function="S11" name="CREATE SESSION REQUEST" changeTime="0.000000" vendorSpecific="false" >
<ie name="GTP_V2_IE_IMSI">311480000002255</ie>
<ie name="GTP_V2_IE_RAT_TYPE">6</ie>
<ie name="GTP_V2_IE_MSISDN">913114802255</ie>
<ieGroup name="GTP_V2_IE_FQ_CSID" >
<ie name="INSTANCE">0</ie>
<ie name="GTP_V2_IE_FQ_CSID">1</ie>
</ieGroup>
<ieGroup name="GTP_V2_IE_BEARER_CNTXT" >
<ie name="INSTANCE">0</ie>
<ie name="GTP_V2_IE_EBI">5</ie>
<ieGroup name="GTP_V2_IE_BEARER_QOS" >
<ie name="ARP">92</ie>
<ie name="QCI">9</ie>
<ie name="UPLINK_MBR">0</ie>
<ie name="DOWNLINK_MBR">0</ie>
<ie name="UPLINK_GBR">0</ie>
<ie name="DOWNLINK_GBR">0</ie>
</ieGroup>
</ieGroup>
<ie name="GTP_V2_IE_APN">vzwinternet.mnc480.mcc311.gprs</ie>
</msg>
<traceSessionRef >
<MCC>311</MCC>
<MNC>480</MNC>
<TRACE_ID>8323073</TRACE_ID>
</traceSessionRef>
</traceRecSession>
</traceCollecFile>

我只需要属性值为GTP_V2_IE_MSISDN的元素。我尝试过使用xpath在php中编写代码。

<?php
$doc = new DOMDocument();
$doc->load('1.xml');
$xpath = new DOMXPath($doc);
// If you want to read exact attribute
//Selects all the ie elements that have a "name" attribute with a value of "GTP_V2_IE_MSISDN".
 $MSISDN = $xpath->query("//traceCollecFile/traceRecSession/msg/ie[@name='GTP_V2_IE_MSISDN']");
 if ($MSISDN->length > 0) {
    echo $MSISDN->item(0)->value;
 }

但是当我在browser.On控制台中运行时，输出中什么也没有显示，代码中什么也没有显示，正文是空的。请帮帮忙，出什么事了？谢谢!

Answer 1

你需要检查你的xpath表达式，如果GTP_V2_IE_MSISDN是唯一的，你可以使用//ie[@name='GTP_V2_IE_MSISDN']代替无效路径。

$MSISDN = $xpath->query("//ie[@name='GTP_V2_IE_MSISDN']");

Answer 2

您有一个默认的名称空间。

xmlns="http://www.3gpp.org/ftp/specs/archive/32_series/32.423#traceData" 

在php中定义它或尝试下面的表达式

//@*[. = "GTP_V2_IE_MSISDN"]/..