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

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

You can also browse Jackson Databind Source Code below:

⏎ com/fasterxml/jackson/databind/deser/impl/PropertyBasedCreator.java

package com.fasterxml.jackson.databind.deser.impl;

import java.io.IOException;
import java.util.*;

import com.fasterxml.jackson.core.JsonParser;

import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.deser.SettableBeanProperty;
import com.fasterxml.jackson.databind.deser.ValueInstantiator;

/**
 * Object that is used to collect arguments for non-default creator
 * (non-default-constructor, or argument-taking factory method)
 * before creator can be called.
 * Since ordering of JSON properties is not guaranteed, this may
 * require buffering of values other than ones being passed to
 * creator.
 */
public final class PropertyBasedCreator
{
    /**
     * Number of properties: usually same as size of {@link #_propertyLookup},
     * but not necessarily, when we have unnamed injectable properties.
     */
    protected final int _propertyCount;

    /**
     * Helper object that knows how to actually construct the instance by
     * invoking creator method with buffered arguments.
     */
    protected final ValueInstantiator _valueInstantiator;

    /**
     * Map that contains property objects for either constructor or factory
     * method (whichever one is null: one property for each
     * parameter for that one), keyed by logical property name
     */
    protected final HashMap<String, SettableBeanProperty> _propertyLookup;

    /**
     * Array that contains properties that expect value to inject, if any;
     * null if no injectable values are expected.
     */
    protected final SettableBeanProperty[] _allProperties;

    /*
    /**********************************************************
    /* Construction, initialization
    /**********************************************************
     */

    protected PropertyBasedCreator(DeserializationContext ctxt,
            ValueInstantiator valueInstantiator,
            SettableBeanProperty[] creatorProps,
            boolean caseInsensitive,
            boolean addAliases)
    {
        _valueInstantiator = valueInstantiator;
        if (caseInsensitive) {
            _propertyLookup = CaseInsensitiveMap.construct(ctxt.getConfig().getLocale());
        } else {
            _propertyLookup = new HashMap<String, SettableBeanProperty>();
        }
        final int len = creatorProps.length;
        _propertyCount = len;
        _allProperties = new SettableBeanProperty[len];

        // 26-Feb-2017, tatu: Let's start by aliases, so that there is no
        //    possibility of accidental override of primary names
        if (addAliases) {
            final DeserializationConfig config = ctxt.getConfig();
            for (SettableBeanProperty prop : creatorProps) {
                // 22-Jan-2018, tatu: ignorable entries should be ignored, even if got aliases
                if (!prop.isIgnorable()) {
                    List<PropertyName> aliases = prop.findAliases(config);
                    if (!aliases.isEmpty()) {
                        for (PropertyName pn : aliases) {
                            _propertyLookup.put(pn.getSimpleName(), prop);
                        }
                    }
                }
            }
        }
        for (int i = 0; i < len; ++i) {
            SettableBeanProperty prop = creatorProps[i];
            _allProperties[i] = prop;
            // 22-Jan-2018, tatu: ignorable entries should be skipped
            if (!prop.isIgnorable()) {
                _propertyLookup.put(prop.getName(), prop);
            }
        }
    }

    /**
     * Factory method used for building actual instances to be used with POJOS:
     * resolves deserializers, checks for "null values".
     *
     * @since 2.9
     */
    public static PropertyBasedCreator construct(DeserializationContext ctxt,
            ValueInstantiator valueInstantiator, SettableBeanProperty[] srcCreatorProps,
            BeanPropertyMap allProperties)
        throws JsonMappingException
    {
        final int len = srcCreatorProps.length;
        SettableBeanProperty[] creatorProps = new SettableBeanProperty[len];
        for (int i = 0; i < len; ++i) {
            SettableBeanProperty prop = srcCreatorProps[i];
            if (!prop.hasValueDeserializer()) {
                // 15-Apr-2020, tatu: [databind#962] Avoid getting deserializer for Inject-only
                //     cases
                if (!prop.isInjectionOnly()) {
                    prop = prop.withValueDeserializer(ctxt.findContextualValueDeserializer(prop.getType(), prop));
                }
            }
            creatorProps[i] = prop;
        }
        return new PropertyBasedCreator(ctxt, valueInstantiator, creatorProps,
                allProperties.isCaseInsensitive(),
// 05-Sep-2019, tatu: As per [databind#2378] looks like not all aliases get merged into
//    `allProperties` so force lookup anyway.
//                allProperties.hasAliases()
                true);
    }

    /**
     * Factory method used for building actual instances to be used with types
     * OTHER than POJOs.
     * resolves deserializers and checks for "null values".
     *
     * @since 2.9
     */
    public static PropertyBasedCreator construct(DeserializationContext ctxt,
            ValueInstantiator valueInstantiator, SettableBeanProperty[] srcCreatorProps,
            boolean caseInsensitive)
        throws JsonMappingException
    {
        final int len = srcCreatorProps.length;
        SettableBeanProperty[] creatorProps = new SettableBeanProperty[len];
        for (int i = 0; i < len; ++i) {
            SettableBeanProperty prop = srcCreatorProps[i];
            if (!prop.hasValueDeserializer()) {
                prop = prop.withValueDeserializer(ctxt.findContextualValueDeserializer(prop.getType(), prop));
            }
            creatorProps[i] = prop;
        }
        return new PropertyBasedCreator(ctxt, valueInstantiator, creatorProps, 
                caseInsensitive, false);
    }

    @Deprecated // since 2.9
    public static PropertyBasedCreator construct(DeserializationContext ctxt,
            ValueInstantiator valueInstantiator, SettableBeanProperty[] srcCreatorProps)
        throws JsonMappingException
    {
        return construct(ctxt, valueInstantiator, srcCreatorProps,
                ctxt.isEnabled(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES));
    }

    /*
    /**********************************************************
    /* Accessors
    /**********************************************************
     */

    public Collection<SettableBeanProperty> properties() {
        return _propertyLookup.values();
    }

    public SettableBeanProperty findCreatorProperty(String name) {
        return _propertyLookup.get(name);
    }

    public SettableBeanProperty findCreatorProperty(int propertyIndex) {
        for (SettableBeanProperty prop : _propertyLookup.values()) {
            if (prop.getPropertyIndex() == propertyIndex) {
                return prop;
            }
        }
        return null;
    }

    /*
    /**********************************************************
    /* Building process
    /**********************************************************
     */

    /**
     * Method called when starting to build a bean instance.
     * 
     * @since 2.1 (added ObjectIdReader parameter -- existed in previous versions without)
     */
    public PropertyValueBuffer startBuilding(JsonParser p, DeserializationContext ctxt,
            ObjectIdReader oir) {
        return new PropertyValueBuffer(p, ctxt, _propertyCount, oir);
    }

    public Object build(DeserializationContext ctxt, PropertyValueBuffer buffer) throws IOException
    {
        Object bean = _valueInstantiator.createFromObjectWith(ctxt,
                _allProperties, buffer);
        // returning null isn't quite legal, but let's let caller deal with that
        if (bean != null) {
            // Object Id to handle?
            bean = buffer.handleIdValue(ctxt, bean);
            
            // Anything buffered?
            for (PropertyValue pv = buffer.buffered(); pv != null; pv = pv.next) {
                pv.assign(bean);
            }
        }
        return bean;
    }

    /*
    /**********************************************************
    /* Helper classes
    /**********************************************************
     */

    /**
     * Simple override of standard {@link java.util.HashMap} to support
     * case-insensitive access to creator properties
     *
     * @since 2.8.5
     */
    static class CaseInsensitiveMap extends HashMap<String, SettableBeanProperty>
    {
        private static final long serialVersionUID = 1L;

        /**
         * Lower-casing can have Locale-specific minor variations.
         *
         * @since 2.11
         */
        protected final Locale _locale;

        @Deprecated // since 2.11
        public CaseInsensitiveMap() {
            this(Locale.getDefault());
        }

        // @since 2.11
        public CaseInsensitiveMap(Locale l) {
            _locale = l;
        }

        // @since 2.11
        public static CaseInsensitiveMap construct(Locale l) {
            return new CaseInsensitiveMap(l);
        }
        
        @Override
        public SettableBeanProperty get(Object key0) {
            return super.get(((String) key0).toLowerCase(_locale));
        }

        @Override
        public SettableBeanProperty put(String key, SettableBeanProperty value) {
            key = key.toLowerCase(_locale);
            return super.put(key, value);
        }
    }
}

⏎ com/fasterxml/jackson/databind/deser/impl/PropertyBasedCreator.java

Or download all of them as a single archive file:

File name: jackson-databind-2.14.0-sources.jar
File size: 1187952 bytes
Release date: 2022-11-05
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