[Java] Serialize POJO to XML according to XSD

If you generate a class from an XSD schema, it will come with the necessary annotations to serialize it to an XML String.

You can therefore easily convert it with:

import jakarta.xml.bind.JAXBContext;
import jakarta.xml.bind.Marshaller;
import java.io.StringWriter;

/**
 * Provides utility methods for serialization scenarios
 */
public class SerializationUtils {

  /**
   * Serialize the given object to XML String using JAXBContext
   * It will set the output to be pretty printed
   * It relies on the object annotations to correctly place and annotate all fields
   * @param object
   * @return the string representation of this object as XML
   * @param <T>
   */
  public static <T> String serializeXml(T object) {
    try {
      JAXBContext jc = JAXBContext.newInstance(object.getClass());

      Marshaller marshaller = jc.createMarshaller();
      marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
      //to completely remove the xml preamble `<?xml version="1.0" encoding="UTF-8" standalone="yes"?>` add this line:
      //marshaller.setProperty(Marshaller.JAXB_FRAGMENT, true);

      //marshaller cannot output to string directly
      StringWriter sw = new StringWriter();

      marshaller.marshal(object, sw);

      return sw.toString();
    } catch (Exception e) {
      throw new RuntimeException("Failed to convert payload to xml. ", e);
    }
  }
}

[Java] Generate POJO from XSD in Maven

Assuming you have a nice correct XSD file with proper namespace references and all, then you could convert it to a POJO (or more) using jaxb-maven-plugin

There are multiple plugins that would achieve the same result and multiple versions of this plugin even, so searching on the web can be confusing. In year 2024, this works simply with adding a plugin in the POM:

<plugin>
  <groupId>org.jvnet.jaxb</groupId>
  <artifactId>jaxb-maven-plugin</artifactId>
  <version>4.0.8</version>
  <executions>
    <execution>
      <id>NAME_FOR_THIS_RUN</id>
      <goals>
        <goal>generate</goal>
      </goals>
      <configuration>
        <schemaDirectory>src/main/resources/FOLDER/USE_CASE</schemaDirectory> <!-- here will be the XSD -->
      </configuration>
    </execution>
  </executions>
</plugin>