Jackson is "the Java JSON library" or "the best JSON parser for Java". Or simply as "JSON for Java".

Jackson also allows you to parse or generate XML messages with the Jackson Dataformat XML Extension.

Jackson Dataformat XML Source Code files are provided in the source packge (jackson-dataformat-xml-2.14.0-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Dataformat XML Source Code below:

⏎ com/fasterxml/jackson/dataformat/xml/deser/XmlReadContext.java

package com.fasterxml.jackson.dataformat.xml.deser;

import java.util.Set;

import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.core.io.CharTypes;
import com.fasterxml.jackson.core.io.ContentReference;

/**
 * Extension of {@link JsonStreamContext}, which implements
 * core methods needed, and adds small amount of additional
 * state data we need.
 *<p>
 * Almost same as standard <code>JsonReaderContext</code>, but
 * custom version needed to be able to keep track of names
 * of properties that need wrapping; this is needed to
 * support wrapped/unwrapped Collection/array values.
 */
public final class XmlReadContext
    extends JsonStreamContext
{
    // // // Configuration

    protected final XmlReadContext _parent;

    // // // Location information (minus source reference)

    protected int _lineNr;
    protected int _columnNr;

    protected String _currentName;

    /**
     * @since 2.9
     */
    protected Object _currentValue;

    protected Set<String> _namesToWrap;

    /**
     * Name of property that requires wrapping
     */
    protected String _wrappedName;

    /*
    /**********************************************************************
    /* Simple instance reuse slots; speeds up things a bit (10-15%)
    /* for docs with lots of small arrays/objects (for which allocation was
    /* visible in profile stack frames)
    /**********************************************************************
     */

    protected XmlReadContext _child = null;

    /*
    /**********************************************************************
    /* Instance construction, reuse
    /**********************************************************************
     */

    public XmlReadContext(XmlReadContext parent, int type, int lineNr, int colNr)
    {
        super();
        _type = type;
        _parent = parent;
        _lineNr = lineNr;
        _columnNr = colNr;
        _index = -1;
    }

    protected final void reset(int type, int lineNr, int colNr)
    {
        _type = type;
        _index = -1;
        _lineNr = lineNr;
        _columnNr = colNr;
        _currentName = null;
        _currentValue = null;
        _namesToWrap = null;
    }

    @Override
    public Object getCurrentValue() {
        return _currentValue;
    }

    @Override
    public void setCurrentValue(Object v) {
        _currentValue = v;
    }

    /*
    /**********************************************************************
    /* Factory methods
    /**********************************************************************
     */

    public static XmlReadContext createRootContext(int lineNr, int colNr) {
        return new XmlReadContext(null, TYPE_ROOT, lineNr, colNr);
    }

    public static XmlReadContext createRootContext() {
        return new XmlReadContext(null, TYPE_ROOT, 1, 0);
    }
    
    public final XmlReadContext createChildArrayContext(int lineNr, int colNr)
    {
        ++_index; // not needed for Object, but does not hurt so no need to check curr type
        XmlReadContext ctxt = _child;
        if (ctxt == null) {
            _child = ctxt = new XmlReadContext(this, TYPE_ARRAY, lineNr, colNr);
            return ctxt;
        }
        ctxt.reset(TYPE_ARRAY, lineNr, colNr);
        return ctxt;
    }

    public final XmlReadContext createChildObjectContext(int lineNr, int colNr)
    {
        ++_index; // not needed for Object, but does not hurt so no need to check curr type
        XmlReadContext ctxt = _child;
        if (ctxt == null) {
            _child = ctxt = new XmlReadContext(this, TYPE_OBJECT, lineNr, colNr);
            return ctxt;
        }
        ctxt.reset(TYPE_OBJECT, lineNr, colNr);
        return ctxt;
    }

    /*
    /**********************************************************************
    /* Abstract method implementation, overrides
    /**********************************************************************
     */

    @Override
    public final String getCurrentName() { return _currentName; }

    // @since 2.9
    @Override public boolean hasCurrentName() { return _currentName != null; }

    @Override
    public final XmlReadContext getParent() { return _parent; }

    /**
     * @return Location pointing to the point where the context
     *   start marker was found
     */
    @Override
    public final JsonLocation startLocation(ContentReference srcRef) {
        // We don't keep track of offsets at this level (only reader does)
        long totalChars = -1L;

        return new JsonLocation(srcRef, totalChars, _lineNr, _columnNr);
    }

    /*
    /**********************************************************************
    /* Extended API
    /**********************************************************************
     */

    /**
     * Method called to mark start of new value, mostly to update `index`
     * for Array and Root contexts.
     *
     * @since 2.12
     */
    public final void valueStarted() {
        ++_index;
    }

    public void setCurrentName(String name) {
        _currentName = name;
    }

    public void setNamesToWrap(Set<String> namesToWrap) {
        _namesToWrap = namesToWrap;
    }

    // @since 2.11.1
    public boolean shouldWrap(String localName) {
        return (_namesToWrap != null) && _namesToWrap.contains(localName);
    }

    protected void convertToArray() {
        _type = TYPE_ARRAY;
    }
    
    /*
    /**********************************************************************
    /* Overridden standard methods
    /**********************************************************************
     */

    /**
     * Overridden to provide developer readable "JsonPath" representation
     * of the context.
     */
    @Override
    public final String toString()
    {
        StringBuilder sb = new StringBuilder(64);
        switch (_type) {
        case TYPE_ROOT:
            sb.append("/");
            break;
        case TYPE_ARRAY:
            sb.append('[');
            sb.append(getCurrentIndex());
            sb.append(']');
            break;
        case TYPE_OBJECT:
            sb.append('{');
            if (_currentName != null) {
                sb.append('"');
                CharTypes.appendQuoted(sb, _currentName);
                sb.append('"');
            } else {
                sb.append('?');
            }
            sb.append('}');
            break;
        }
        return sb.toString();
    }
}

⏎ com/fasterxml/jackson/dataformat/xml/deser/XmlReadContext.java

Or download all of them as a single archive file:

File name: jackson-dataformat-xml-2.14.0-sources.jar
File size: 98015 bytes
Release date: 2022-11-05
Download 

⇒ Download Jackson Dataformat Binary Packages

⇐ Jackson Dataformat Extensions

⇑ Downloading and Reviewing jackson-*.jar

⇑⇑ Jackson - Java JSON library