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/DeserializerFactory.java

package com.fasterxml.jackson.databind.deser;

import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.jsontype.TypeDeserializer;
import com.fasterxml.jackson.databind.type.*;

/**
 * Abstract class that defines API used by {@link DeserializationContext}
 * to construct actual
 * {@link JsonDeserializer} instances (which are then cached by
 * context and/or dedicated cache).
 *<p>
 * Since there are multiple broad categories of deserializers, there are 
 * multiple factory methods:
 *<ul>
 * <li>For JSON "Array" type, we need 2 methods: one to deal with expected
 *   Java arrays ({@link #createArrayDeserializer})
 *   and the other for other Java containers like {@link java.util.List}s
 *   and {@link java.util.Set}s ({@link #createCollectionDeserializer}).
 *   Actually there is also a third method for "Collection-like" types;
 *   things like Scala collections that act like JDK collections but do not
 *   implement same interfaces.
 *  </li>
 * <li>For JSON "Object" type, we need 2 methods: one to deal with
 *   expected Java {@link java.util.Map}s
 *   ({@link #createMapDeserializer}), and another for POJOs
 *   ({@link #createBeanDeserializer}.
 *   As an additional twist there is also a callback for "Map-like" types,
 *   mostly to make it possible to support Scala Maps (which are NOT JDK
 *   Map compatible).
 *  </li>
 * <li>For Tree Model ({@link com.fasterxml.jackson.databind.JsonNode}) properties there is
 *    {@link #createTreeDeserializer}
 * <li>For enumerated types ({@link java.lang.Enum}) there is
 *    {@link #createEnumDeserializer}
 *  </li>
 * <li>For all other types, {@link #createBeanDeserializer} is used.
 * </ul>
 *<p>
 */
public abstract class DeserializerFactory
{
    protected final static Deserializers[] NO_DESERIALIZERS = new Deserializers[0];

    /*
    /********************************************************
    /* Configuration handling
    /********************************************************
     */

    /**
     * Convenience method for creating a new factory instance with additional deserializer
     * provider.
     */
    public abstract DeserializerFactory withAdditionalDeserializers(Deserializers additional);

    /**
     * Convenience method for creating a new factory instance with additional
     * {@link KeyDeserializers}.
     */
    public abstract DeserializerFactory withAdditionalKeyDeserializers(KeyDeserializers additional);
    
    /**
     * Convenience method for creating a new factory instance with additional
     * {@link BeanDeserializerModifier}.
     */
    public abstract DeserializerFactory withDeserializerModifier(BeanDeserializerModifier modifier);

    /**
     * Convenience method for creating a new factory instance with additional
     * {@link AbstractTypeResolver}.
     */
    public abstract DeserializerFactory withAbstractTypeResolver(AbstractTypeResolver resolver);

    /**
     * Convenience method for creating a new factory instance with additional
     * {@link ValueInstantiators}.
     */
    public abstract DeserializerFactory withValueInstantiators(ValueInstantiators instantiators);
    
    /*
    /**********************************************************
    /* Basic DeserializerFactory API:
    /**********************************************************
     */

    /**
     * Method that can be called to try to resolve an abstract type
     * (interface, abstract class) into a concrete type, or at least
     * something "more concrete" (abstract class instead of interface).
     * Will either return passed type, or a more specific type.
     */
    public abstract JavaType mapAbstractType(DeserializationConfig config, JavaType type)
        throws JsonMappingException;

    /**
     * Method that is to find all creators (constructors, factory methods)
     * for the bean type to deserialize.
     */
    public abstract ValueInstantiator findValueInstantiator(DeserializationContext ctxt,
            BeanDescription beanDesc)
        throws JsonMappingException;
    
    /**
     * Method called to create (or, for completely immutable deserializers,
     * reuse) a deserializer that can convert JSON content into values of
     * specified Java "bean" (POJO) type.
     * At this point it is known that the type is not otherwise recognized
     * as one of structured types (array, Collection, Map) or a well-known
     * JDK type (enum, primitives/wrappers, String); this method only
     * gets called if other options are exhausted. This also means that
     * this method can be overridden to add support for custom types.
     *
     * @param type Type to be deserialized
     */
    public abstract JsonDeserializer<Object> createBeanDeserializer(DeserializationContext ctxt,
            JavaType type, BeanDescription beanDesc)
        throws JsonMappingException;

    /**
     * Method called to create a deserializer that will use specified Builder
     * class for building value instances.
     */
    public abstract JsonDeserializer<Object> createBuilderBasedDeserializer(
    		DeserializationContext ctxt, JavaType type, BeanDescription beanDesc,
    		Class<?> builderClass)
        throws JsonMappingException;


    public abstract JsonDeserializer<?> createEnumDeserializer(DeserializationContext ctxt,
            JavaType type, BeanDescription beanDesc)
        throws JsonMappingException;

    /**
     * @since 2.7
     */
    public abstract JsonDeserializer<?> createReferenceDeserializer(DeserializationContext ctxt,
            ReferenceType type, BeanDescription beanDesc)
        throws JsonMappingException;
    
    /**
     * Method called to create and return a deserializer that can construct
     * JsonNode(s) from JSON content.
     */
    public abstract JsonDeserializer<?> createTreeDeserializer(DeserializationConfig config,
            JavaType type, BeanDescription beanDesc)
        throws JsonMappingException;
    
    /**
     * Method called to create (or, for completely immutable deserializers,
     * reuse) a deserializer that can convert JSON content into values of
     * specified Java type.
     *
     * @param type Type to be deserialized
     */
    public abstract JsonDeserializer<?> createArrayDeserializer(DeserializationContext ctxt,
            ArrayType type, BeanDescription beanDesc)
        throws JsonMappingException;

    public abstract JsonDeserializer<?> createCollectionDeserializer(DeserializationContext ctxt,
            CollectionType type, BeanDescription beanDesc)
        throws JsonMappingException;

    public abstract JsonDeserializer<?> createCollectionLikeDeserializer(DeserializationContext ctxt,
            CollectionLikeType type, BeanDescription beanDesc)
        throws JsonMappingException;

    public abstract JsonDeserializer<?> createMapDeserializer(DeserializationContext ctxt,
            MapType type, BeanDescription beanDesc)
        throws JsonMappingException;

    public abstract JsonDeserializer<?> createMapLikeDeserializer(DeserializationContext ctxt,
            MapLikeType type, BeanDescription beanDesc)
        throws JsonMappingException;

    /**
     * Method called to find if factory knows how to create a key deserializer
     * for specified type; currently this means checking if a module has registered
     * possible deserializers.
     * 
     * @return Key deserializer to use for specified type, if one found; null if not
     *   (and default key deserializer should be used)
     */
    public abstract KeyDeserializer createKeyDeserializer(DeserializationContext ctxt,
            JavaType type)
        throws JsonMappingException;

    /**
     * Method called to find and create a type information deserializer for given base type,
     * if one is needed. If not needed (no polymorphic handling configured for type),
     * should return null.
     *<p>
     * Note that this method is usually only directly called for values of container (Collection,
     * array, Map) types and root values, but not for bean property values.
     *
     * @param baseType Declared base type of the value to deserializer (actual
     *    deserializer type will be this type or its subtype)
     * 
     * @return Type deserializer to use for given base type, if one is needed; null if not.
     */
    public abstract TypeDeserializer findTypeDeserializer(DeserializationConfig config,
            JavaType baseType)
        throws JsonMappingException;

    /**
     * Method that can be used to check if databind module has explicitly declared deserializer
     * for given (likely JDK) type, explicit meaning that there is specific deserializer for
     * given type as opposed to auto-generated "Bean" deserializer. Factory itself will check
     * for known JDK-provided types, but registered {@link com.fasterxml.jackson.databind.Module}s
     * are also called to see if they might provide explicit deserializer.
     *<p> 
     * Main use for this method is with Safe Default Typing (and generally Safe Polymorphic
     * Deserialization), during which it is good to be able to check that given raw type
     * is explicitly supported and as such "known type" (as opposed to potentially
     * dangerous "gadget type" which could be exploited).
     *<p>
     * This matches {@code Deserializers.Base.hasDeserializerFor(Class)} method, which is
     * the mechanism used to determine if a {@code Module} might provide an explicit
     * deserializer instead of core databind.
     *
     * @since 2.11
     */
    public abstract boolean hasExplicitDeserializerFor(DeserializationConfig config,
            Class<?> valueType);
}

⏎ com/fasterxml/jackson/databind/deser/DeserializerFactory.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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