Generate Plain Old Java Objects (POJOs) from XML Schema Definitions with xjc

Yesterday I was fighting with an incredibly annoying issue with Jackson's XML extension suddenly deciding to stop parsing my site's sitemap.xml.

While endlessly trawling through Stack Overflow posts, I found this Stack Overflow answer which mentioned the use of the command xjc, which is bundled in the JDK!

This command takes a given XSD file and generates the given Java classes from that schema, even from a URL:

$ xjc https://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd
parsing a schema...
compiling a schema...
org/sitemaps/schemas/sitemap/_0/ObjectFactory.java
org/sitemaps/schemas/sitemap/_0/TChangeFreq.java
org/sitemaps/schemas/sitemap/_0/TUrl.java
org/sitemaps/schemas/sitemap/_0/Urlset.java
org/sitemaps/schemas/sitemap/_0/package-info.java

I thought this was pretty great for folks who work with XSD-defined content types, not least because the generated class is pretty nice, with a fair few comments and a nice interface to the POJO:

//
// This file was generated by the JavaTM Architecture for XML Binding(JAXB) Reference Implementation, v2.2.8-b130911.1802
// See <a href="http://java.sun.com/xml/jaxb">http://java.sun.com/xml/jaxb</a>
// Any modifications to this file will be lost upon recompilation of the source schema.
// Generated on: 2020.02.03 at 08:40:05 PM GMT
//


package org.sitemaps.schemas.sitemap._0;

import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAnyElement;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlSchemaType;
import javax.xml.bind.annotation.XmlType;


/**
 *
 *         Container for the data needed to describe a document to crawl.
 *
 *
 * <p>Java class for tUrl complex type.
 *
 * <p>The following schema fragment specifies the expected content contained within this class.
 *
 * <pre>
 * &lt;complexType name="tUrl">
 *   &lt;complexContent>
 *     &lt;restriction base="{http://www.w3.org/2001/XMLSchema}anyType">
 *       &lt;sequence>
 *         &lt;element name="loc" type="{http://www.sitemaps.org/schemas/sitemap/0.9}tLoc"/>
 *         &lt;element name="lastmod" type="{http://www.sitemaps.org/schemas/sitemap/0.9}tLastmod" minOccurs="0"/>
 *         &lt;element name="changefreq" type="{http://www.sitemaps.org/schemas/sitemap/0.9}tChangeFreq" minOccurs="0"/>
 *         &lt;element name="priority" type="{http://www.sitemaps.org/schemas/sitemap/0.9}tPriority" minOccurs="0"/>
 *         &lt;any namespace='##other' maxOccurs="unbounded" minOccurs="0"/>
 *       &lt;/sequence>
 *     &lt;/restriction>
 *   &lt;/complexContent>
 * &lt;/complexType>
 * </pre>
 *
 *
 */
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "tUrl", propOrder = {
    "loc",
    "lastmod",
    "changefreq",
    "priority",
    "any"
})
public class TUrl {

    @XmlElement(required = true)
    @XmlSchemaType(name = "anyURI")
    protected String loc;
    protected String lastmod;
    @XmlSchemaType(name = "string")
    protected TChangeFreq changefreq;
    protected BigDecimal priority;
    @XmlAnyElement(lax = true)
    protected List<Object> any;

    /**
     * Gets the value of the loc property.
     *
     * @return
     *     possible object is
     *     {@link String }
     *
     */
    public String getLoc() {
        return loc;
    }

    /**
     * Sets the value of the loc property.
     *
     * @param value
     *     allowed object is
     *     {@link String }
     *
     */
    public void setLoc(String value) {
        this.loc = value;
    }

    /**
     * Gets the value of the lastmod property.
     *
     * @return
     *     possible object is
     *     {@link String }
     *
     */
    public String getLastmod() {
        return lastmod;
    }

    /**
     * Sets the value of the lastmod property.
     *
     * @param value
     *     allowed object is
     *     {@link String }
     *
     */
    public void setLastmod(String value) {
        this.lastmod = value;
    }

    /**
     * Gets the value of the changefreq property.
     *
     * @return
     *     possible object is
     *     {@link TChangeFreq }
     *
     */
    public TChangeFreq getChangefreq() {
        return changefreq;
    }

    /**
     * Sets the value of the changefreq property.
     *
     * @param value
     *     allowed object is
     *     {@link TChangeFreq }
     *
     */
    public void setChangefreq(TChangeFreq value) {
        this.changefreq = value;
    }

    /**
     * Gets the value of the priority property.
     *
     * @return
     *     possible object is
     *     {@link BigDecimal }
     *
     */
    public BigDecimal getPriority() {
        return priority;
    }

    /**
     * Sets the value of the priority property.
     *
     * @param value
     *     allowed object is
     *     {@link BigDecimal }
     *
     */
    public void setPriority(BigDecimal value) {
        this.priority = value;
    }

    /**
     * Gets the value of the any property.
     *
     * <p>
     * This accessor method returns a reference to the live list,
     * not a snapshot. Therefore any modification you make to the
     * returned list will be present inside the JAXB object.
     * This is why there is not a <CODE>set</CODE> method for the any property.
     *
     * <p>
     * For example, to add a new item, do as follows:
     * <pre>
     *    getAny().add(newItem);
     * </pre>
     *
     *
     * <p>
     * Objects of the following type(s) are allowed in the list
     * {@link Object }
     *
     *
     */
    public List<Object> getAny() {
        if (any == null) {
            any = new ArrayList<Object>();
        }
        return this.any;
    }

}

You can also handle this with the Mojohaus jaxb2-maven-plugin.

Written by Jamie Tanna's profile image Jamie Tanna on , and last updated on .

Content for this article is shared under the terms of the Creative Commons Attribution Non Commercial Share Alike 4.0 International, and code is shared under the Apache License 2.0.

#blogumentation #java #xml.

This post was filed under articles.

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