The behavior of javax.xml.transform.Transformer changed considerably.
Take the following sequence:
// prepare an XML file as a DOM Source
String xml = "...";
Document document = DocumentBuilderFactory
.newInstance()
.newDocumentBuilder()
.parse(new InputSource(new StringReader(xml)));
// maybe add some nodes or CDATA content
// transform the XML
Source source = new DOMSource(document);
Transformer transformer = TransformerFactory.newInstance().newTransformer();
// maybe configure transformer
StringWriter outputWriter = new StringWriter();
transformer.transform(source, new StreamResult(outputWriter));
String transformedXml = outputWriter.toString();
// now compare `xml` and `transformedXml`Then the behavior between Java 8 and 9, with and without configuration, and with and without xml:space="preserve" differs.
This is the most common behavior:
- existing indentation remains
- new nodes, including CDATA are inline
It can be observed on Java 8 and 9 if the transformer was not configured beyond defaults and regardless of xml:space="preserve".
But when you configure the transformer with OutputKeys.INDENT=yes and indent-amount=4 Java 8 and 9 behave differently.
On Java 8 you get:
- existing indentation remains
- new nodes are indented according to the settings
- CDATA is not indented
On Java 9, though, this happens:
- entire document is indented according to settings, including a bunch of spurious empty lines
- accordingly, new nodes are indented
- CDATA is put onto new lines and indented as well, fundamentally changing the XML!
Furthermore, with further configuration it becomes apparent that xml:space="preserve" behaves differently as well.
On Java 8 it has no effect, on Java 9 it drops us back into the "nothing changes" case described first.
The test demonstrates that behavior, using JUnit 5's cool nested tests.
(Last checked: 8u152 and 9.0.1)