如何使用XMLReader读取带有未定义命名空间的XML文件？

Question

我对解析XML文件相对较新,并且正在尝试使用XMLReader读取大型XML文件.

<?xml version="1.0" encoding="UTF-8"?>
<ShowVehicleRemarketing environment="Production" lang="en-CA" release="8.1-Lite" xsi:schemaLocation="http://www.starstandards.org/STAR /STAR/Rev4.2.4/BODs/Standalone/ShowVehicleRemarketing.xsd">
  <ApplicationArea>
    <Sender>
      <Component>Component</Component>
      <Task>Task</Task>
      <ReferenceId>w5/cron</ReferenceId>
      <CreatorNameCode>CreatorNameCode</CreatorNameCode>
      <SenderNameCode>SenderNameCode</SenderNameCode>
      <SenderURI>http://www.example.com</SenderURI>
      <Language>en-CA</Language>
      <ServiceId>ServiceId</ServiceId>
    </Sender>
    <CreationDateTime>CreationDateTime</CreationDateTime>
    <Destination>
      <DestinationNameCode>example</DestinationNameCode>
    </Destination>
  </ApplicationArea>
...

我收到以下错误

ErrorException [警告]:XMLReader :: read()[xmlreader.read]:compress.zlib:// D:/WebDev/example/local/public/../upload/example.xml.gz:2:名称空间错误:未定义ShowVehicleRemarketing上schemaLocation的命名空间前缀xsi

我一直在搜索并找不到有关使用XMLReader读取带有命名空间的XML文件的更多有用信息 - 我如何定义命名空间,如果这实际上是我需要做什么...帮助不大？链接到相关资源？

Answer 1

需要有xsi命名空间的定义.例如

<ShowVehicleRemarketing
  environment="Production"
  lang="en-CA"
  release="8.1-Lite"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.starstandards.org/STAR/STAR/Rev4.2.4/BODs/Standalone/ShowVehicleRemarketing.xsd"
>

更新:您可以编写用户定义的过滤器,然后让XMLReader 使用该过滤器,例如:

stream_filter_register('darn', 'DarnFilter');
$src = 'php://filter/read=darn/resource=compress.zlib://something.xml.gz';
$reader->open($src);

然后,compress.zlib包装器读取的内容通过DarnFilter"路由",DarnFilter必须找到它可以插入xmlns:xsi声明的(第一个)位置.但是这很麻烦并且需要花一些时间来做正确的事(例如理论上桶A可以包含xs,桶B i:schem和桶C aLocation=")

更新2:这是一个特殊的php过滤器示例,它插入了xsi名称空间声明.大部分未经测试(使用我运行的一个测试;-))并且没有记录.把它作为概念验证而不是生产代码.

<?php
stream_filter_register('darn', 'DarnFilter');
$src = 'php://filter/read=darn/resource=compress.zlib://d:/test.xml.gz';

$r = new XMLReader;
$r->open($src);
while($r->read()) {
  echo '.';
}

class DarnFilter extends php_user_filter {
  protected $buffer='';
  protected $status = PSFS_FEED_ME;

  public function filter($in, $out, &$consumed, $closing)
  {
    while ( $bucket = stream_bucket_make_writeable($in) ) {
      $consumed += $bucket->datalen;
      if ( PSFS_PASS_ON == $this->status ) {
        // we're already done, just copy the content
        stream_bucket_append($out, $bucket);
      }
      else {
        $this->buffer .= $bucket->data;
        if ( $this->foo() ) {
          // first element found
          // send the current buffer          
          $bucket->data = $this->buffer;
          $bucket->datalen = strlen($bucket->data);
          stream_bucket_append($out, $bucket);
          $this->buffer = null;
          // no need for further processing
          $this->status = PSFS_PASS_ON;
        }
      }
    }
    return $this->status;
  }

  /* looks for the first (root) element in $this->buffer
  *  if it doesn't contain a xsi namespace decl inserts it
  */
  protected function foo() {
    $rc = false;
    if ( preg_match('!<([^?>\s]+)\s?([^>]*)>!', $this->buffer, $m, PREG_OFFSET_CAPTURE) ) {
      $rc = true;
      if ( false===strpos($m[2][0], 'xmlns:xsi') ) {
        echo ' inserting xsi decl ';
        $in = '<'.$m[1][0]
          . ' xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" '
          . $m[2][0] . '>';    
        $this->buffer = substr($this->buffer, 0, $m[0][1])
          . $in
          . substr($this->buffer, $m[0][1] + strlen($m[0][0]));
      }
    }
    return $rc;
  }
}

更新3:这是一个用C#编写的临时解决方案

XmlNamespaceManager nsmgr = new XmlNamespaceManager(new NameTable());
// prime the XMLReader with the xsi namespace
nsmgr.AddNamespace("xsi", "http://www.w3.org/2001/XMLSchema-instance");

using ( XmlReader reader = XmlTextReader.Create(
  new GZipStream(new FileStream(@"\test.xml.gz", FileMode.Open, FileAccess.Read), CompressionMode.Decompress),
  new XmlReaderSettings(),
  new XmlParserContext(null, nsmgr, null, XmlSpace.None)
)) {
  while (reader.Read())
  {
    System.Console.Write('.');
  }
}