从 XML 标签中删除无效空格的 Java 8 函数

Question

I'm attempting to perform a data migration exercise, loading a series of XML files into a new format. The problem I've identified is that the XML from the legacy app has been generated with invalid tags, ie some of the tags contain whitespaces eg:

<Serial>0001</Serial>
<Document ID>12345</Document ID>
<Document Type>TypeA</Document Type>

Unfortunately there is no staff resource from the legacy system to correct the XML, so my only option is to fix it as I process the data.

Can anyone help with a neat way of using Java 8 to remove the whitespaces from the XML tags, making them valid to parse?

My original code to extract the XML was

final XmlMapper xmlMapper = new XmlMapper();
final JsonNode jsonNode = xmlMapper.readTree(metadata);
return objectMapper.convertValue(jsonNode, new TypeReference<Map<String, String>>() 

Many thanks

Answer 1

This is not Java8-specific solution, but it does what you ask for. Having your entire XML as a string, it uses pattern matching to identify the XML tags, and removes any space character inside them. Finally, correctXmlString has valid XML tags.

String wrongXmlString = <Document ID>12345</Document ID>;

// Regex for matching xml tags
Matcher matcher = Pattern.compile("<[^>]+>").matcher(str);

// String builder for creating the correct XML.
StringBuffer xmlBuilder = new StringBuffer();

while (matcher.find()) 
{
  // for every string match (i.e., for each tag) 
  String tag = matcher.group();
  // remove any spaces and append the correct string
  matcher.appendReplacement(xmlBuilder, tag.replaceAll(" +", ""));
}

matcher.appendTail(xmlBuilder);

String correctXmlString = xmlBuilder.toString();