xmlwriter

This library writes XML either as a SAX2 event filter or as a standalone XML writer. XML can be written as-is or pretty printed. The library has no dependencies on Java XML serialization or JAXB.

Usage

The library is available from Maven Central using the following Maven dependency:

<dependency>
  <groupId>org.cthing</groupId>
  <artifactId>xmlwriter</artifactId>
  <version>4.0.0</version>
</dependency>

or the following Gradle dependency:

implementation("org.cthing:xmlwriter:4.0.0")

Standalone Usage

The XmlWriter class can be used standalone in applications that need to write XML. For standalone usage:

• Create an XmlWriter instance specifying the output destination
• Configure the writer output properties (e.g. enable pretty printing) as needed
• Begin the XML output by calling one of the startDocument methods. One of these methods must be called before any other output methods.
• Call XML output methods as needed (e.g. startElement).
• Complete the XML output by calling the endDocument method to properly terminate the XML document. No XML output methods can be called following the call to endDocument.
• Optionally, reuse the XmlWriter instance by calling the reset method.

The following example uses a standalone XmlWriter to write a simple XML document to the standard output:

XmlWriter w = new XmlWriter();
w.startDocument();
w.startElement("elem1");
w.characters("Hello World");
w.endElement();
w.endDocument();

The following XML is displayed on the standard output:

<?xml version="1.0" standalone="yes"?>
<elem1>Hello World</elem1>

SAX Filter Usage

The XmlWriter can be used as a SAX2 stream filter. The class receives SAX events from a downstream XMLReader, outputs the appropriate XML, and forwards events to the upstream filter. For usage as a SAX filter:

• Create a SAX parser using the appropriate factory
• Create an XmlWriter instance specifying the reader corresponding to the parser and the output destination
• Call the XmlWriter.parse method to parse the document and write its XML to the output. The parse method must be called on the outermost object in the filter chain.
• When used as part of a filter chain, an XmlWriter instance cannot be not reused

In the following example, the XmlWriter is used to output XML that is being parsed by an org.xml.sax.XMLReader and written to the standard output.

final SAXParserFactory factory = SAXParserFactory.newInstance();
factory.setNamespaceAware(true);
factory.setValidating(false);
factory.setXIncludeAware(false);

final SAXParser parser = factory.newSAXParser();
final XMLReader xmlReader = parser.getXMLReader();
final XmlWriter xmlWriter = new XmlWriter(xmlReader);

xmlWriter.setProperty("http://xml.org/sax/properties/lexical-handler", xmlWriter);
xmlWriter.parse(new InputSource(new FileReader("Foo.xml")));

Detailed Usage and Design

See the Javadoc in the XmlWriter class for detailed usage and configuration information. See the State Machine document for details on the formatter state machine at the heart of the XmlWriter class.

Building

The library is compiled for Java 17. If a Java 17 toolchain is not available, one will be downloaded.

Gradle is used to build the library:

./gradlew build

The Javadoc for the library can be generated by running:

./gradlew javadoc

Releasing

This project is released on the Maven Central repository. Perform the following steps to create a release.

• Commit all changes for the release
• In the build.gradle.kts file, edit the ProjectVersion object
  • Set the version for the release. The project follows semantic versioning.
  • Set the build type to BuildType.release
• Commit the changes
• Wait until CI builds the release candidate
• Run the command mkrelease xmlwriter <version>
• In a browser go to the Maven Central Repository Manager
• Log in
• Use the Staging Upload to upload the generated artifact bundle xmlwriter-bundle-<version>.jar
• Click on Staging Repositories
• Once it is enabled, press Release to release the artifacts to Maven Central
• Log out
• Wait for the new release to be available on Maven Central
• In a browser, go to the project on GitHub
• Generate a release with the tag <version>
• In the build.gradle.kts file, edit the ProjectVersion object
  • Increment the version patch number
  • Set the build type to BuildType.snapshot
• Update the CHANGELOG.md with the changes in the release and prepare for next release changes
• Update the Usage section in the README.md with the latest artifact release version
• Commit these changes