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/DefaultDeserializationContext.java

package com.fasterxml.jackson.databind.deser;

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

import com.fasterxml.jackson.annotation.ObjectIdGenerator;
import com.fasterxml.jackson.annotation.ObjectIdResolver;
import com.fasterxml.jackson.annotation.ObjectIdGenerator.IdKey;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonToken;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.cfg.HandlerInstantiator;
import com.fasterxml.jackson.databind.deser.impl.ReadableObjectId;
import com.fasterxml.jackson.databind.deser.impl.ReadableObjectId.Referring;
import com.fasterxml.jackson.databind.introspect.Annotated;
import com.fasterxml.jackson.databind.util.ClassUtil;

/**
 * Complete {@link DeserializationContext} implementation that adds
 * extended API for {@link ObjectMapper} (and {@link ObjectReader})
 * to call, as well as implements certain parts that base class
 * has left abstract.
 * The remaining abstract methods ({@link #createInstance}, {@link #with})
 * are left so that custom implementations will properly implement them
 * to return intended subtype.
 */
public abstract class DefaultDeserializationContext
    extends DeserializationContext
    implements java.io.Serializable // since 2.1
{
    private static final long serialVersionUID = 1L;

    protected transient LinkedHashMap<ObjectIdGenerator.IdKey, ReadableObjectId> _objectIds;

    private List<ObjectIdResolver> _objectIdResolvers;

    /**
     * Constructor that will pass specified deserializer factory and
     * cache: cache may be null (in which case default implementation
     * will be used), factory cannot be null
     */
    protected DefaultDeserializationContext(DeserializerFactory df, DeserializerCache cache) {
        super(df, cache);
    }

    protected DefaultDeserializationContext(DefaultDeserializationContext src,
            DeserializationConfig config, JsonParser p, InjectableValues values) {
        super(src, config, p, values);
    }

    // @since 2.12
    protected DefaultDeserializationContext(DefaultDeserializationContext src,
            DeserializationConfig config) {
        super(src, config);
    }

    protected DefaultDeserializationContext(DefaultDeserializationContext src,
            DeserializerFactory factory) {
        super(src, factory);
    }

    /**
     * @since 2.4.4
     */
    protected DefaultDeserializationContext(DefaultDeserializationContext src) {
        super(src);
    }

    /**
     * Method needed to ensure that {@link ObjectMapper#copy} will work
     * properly; specifically, that caches are cleared, but settings
     * will otherwise remain identical; and that no sharing of state
     * occurs.
     * 
     * @since 2.4.4
     */
    public DefaultDeserializationContext copy() {
        throw new IllegalStateException("DefaultDeserializationContext sub-class not overriding copy()");
    }

    /*
    /**********************************************************
    /* Abstract methods impls, Object Id
    /**********************************************************
     */

    @Override
    public ReadableObjectId findObjectId(Object id, ObjectIdGenerator<?> gen, ObjectIdResolver resolverType)
    {
        // 02-Apr-2015, tatu: As per [databind#742] should allow 'null', similar to how
        //   missing id already works.
        if (id == null) {
            return null;
        }

        final ObjectIdGenerator.IdKey key = gen.key(id);

        if (_objectIds == null) {
            _objectIds = new LinkedHashMap<ObjectIdGenerator.IdKey,ReadableObjectId>();
        } else {
            ReadableObjectId entry = _objectIds.get(key);
            if (entry != null) {
                return entry;
            }
        }

        // Not seen yet, must create entry and configure resolver.
        ObjectIdResolver resolver = null;

        if (_objectIdResolvers == null) {
            _objectIdResolvers = new ArrayList<ObjectIdResolver>(8);
        } else {
            for (ObjectIdResolver res : _objectIdResolvers) {
                if (res.canUseFor(resolverType)) {
                    resolver = res;
                    break;
                }
            }
        }

        if (resolver == null) {
            resolver = resolverType.newForDeserialization(this);
            _objectIdResolvers.add(resolver);
        }

        ReadableObjectId entry = createReadableObjectId(key);
        entry.setResolver(resolver);
        _objectIds.put(key, entry);
        return entry;
    }

    /**
     * Overridable factory method to create a new instance of ReadableObjectId or its
     * subclass. It is meant to be overridden when custom ReadableObjectId is
     * needed for {@link #tryToResolveUnresolvedObjectId}.
     * Default implementation simply constructs default {@link ReadableObjectId} with
     * given <code>key</code>.
     * 
     * @param key The key to associate with the new ReadableObjectId
     * @return New ReadableObjectId instance
     *
     * @since 2.7
     */
    protected ReadableObjectId createReadableObjectId(IdKey key) {
        return new ReadableObjectId(key);
    }

    @Override
    public void checkUnresolvedObjectId() throws UnresolvedForwardReference
    {
        if (_objectIds == null) {
            return;
        }
        // 29-Dec-2014, tatu: As per [databind#299], may also just let unresolved refs be...
        if (!isEnabled(DeserializationFeature.FAIL_ON_UNRESOLVED_OBJECT_IDS)) {
            return;
        }
        UnresolvedForwardReference exception = null;
        for (Entry<IdKey,ReadableObjectId> entry : _objectIds.entrySet()) {
            ReadableObjectId roid = entry.getValue();
            if (!roid.hasReferringProperties()) {
                continue;
            }
            // as per [databind#675], allow resolution at this point
            if (tryToResolveUnresolvedObjectId(roid)) {
                continue;
            }
            if (exception == null) {
                exception = new UnresolvedForwardReference(getParser(), "Unresolved forward references for: ")
                        .withStackTrace();
            }
            Object key = roid.getKey().key;
            for (Iterator<Referring> iterator = roid.referringProperties(); iterator.hasNext(); ) {
                Referring referring = iterator.next();
                exception.addUnresolvedId(key, referring.getBeanType(), referring.getLocation());
            }
        }
        if (exception != null) {
            throw exception;
        }
    }

    /**
     * Overridable helper method called to try to resolve otherwise unresolvable {@link ReadableObjectId};
     * and if this succeeds, return <code>true</code> to indicate problem has been resolved in
     * some way, so that caller can avoid reporting it as an error.
     *<p>
     * Default implementation simply calls {@link ReadableObjectId#tryToResolveUnresolved} and
     * returns whatever it returns.
     *
     * @since 2.6
     */
    protected boolean tryToResolveUnresolvedObjectId(ReadableObjectId roid)
    {
        return roid.tryToResolveUnresolved(this);
    }
    
    /*
    /**********************************************************
    /* Abstract methods impls, other factory methods
    /**********************************************************
     */
    
    @SuppressWarnings("unchecked")
    @Override
    public JsonDeserializer<Object> deserializerInstance(Annotated ann, Object deserDef)
        throws JsonMappingException
    {
        if (deserDef == null) {
            return null;
        }
        JsonDeserializer<?> deser;
        
        if (deserDef instanceof JsonDeserializer) {
            deser = (JsonDeserializer<?>) deserDef;
        } else {
            // Alas, there's no way to force return type of "either class
            // X or Y" -- need to throw an exception after the fact
            if (!(deserDef instanceof Class)) {
                throw new IllegalStateException("AnnotationIntrospector returned deserializer definition of type "+deserDef.getClass().getName()+"; expected type JsonDeserializer or Class<JsonDeserializer> instead");
            }
            Class<?> deserClass = (Class<?>)deserDef;
            // there are some known "no class" markers to consider too:
            if (deserClass == JsonDeserializer.None.class || ClassUtil.isBogusClass(deserClass)) {
                return null;
            }
            if (!JsonDeserializer.class.isAssignableFrom(deserClass)) {
                throw new IllegalStateException("AnnotationIntrospector returned Class "+deserClass.getName()+"; expected Class<JsonDeserializer>");
            }
            HandlerInstantiator hi = _config.getHandlerInstantiator();
            deser = (hi == null) ? null : hi.deserializerInstance(_config, ann, deserClass);
            if (deser == null) {
                deser = (JsonDeserializer<?>) ClassUtil.createInstance(deserClass,
                        _config.canOverrideAccessModifiers());
            }
        }
        // First: need to resolve
        if (deser instanceof ResolvableDeserializer) {
            ((ResolvableDeserializer) deser).resolve(this);
        }
        return (JsonDeserializer<Object>) deser;
    }

    @Override
    public final KeyDeserializer keyDeserializerInstance(Annotated ann, Object deserDef)
        throws JsonMappingException
    {
        if (deserDef == null) {
            return null;
        }

        KeyDeserializer deser;
        
        if (deserDef instanceof KeyDeserializer) {
            deser = (KeyDeserializer) deserDef;
        } else {
            if (!(deserDef instanceof Class)) {
                throw new IllegalStateException("AnnotationIntrospector returned key deserializer definition of type "
                        +deserDef.getClass().getName()
                        +"; expected type KeyDeserializer or Class<KeyDeserializer> instead");
            }
            Class<?> deserClass = (Class<?>)deserDef;
            // there are some known "no class" markers to consider too:
            if (deserClass == KeyDeserializer.None.class || ClassUtil.isBogusClass(deserClass)) {
                return null;
            }
            if (!KeyDeserializer.class.isAssignableFrom(deserClass)) {
                throw new IllegalStateException("AnnotationIntrospector returned Class "+deserClass.getName()
                        +"; expected Class<KeyDeserializer>");
            }
            HandlerInstantiator hi = _config.getHandlerInstantiator();
            deser = (hi == null) ? null : hi.keyDeserializerInstance(_config, ann, deserClass);
            if (deser == null) {
                deser = (KeyDeserializer) ClassUtil.createInstance(deserClass,
                        _config.canOverrideAccessModifiers());
            }
        }
        // First: need to resolve
        if (deser instanceof ResolvableDeserializer) {
            ((ResolvableDeserializer) deser).resolve(this);
        }
        return deser;
    }

    /*
    /**********************************************************
    /* Extended API, life-cycle
    /**********************************************************
     */

    /**
     * Fluent factory method used for constructing a blueprint instance
     * with different factory
     */
    public abstract DefaultDeserializationContext with(DeserializerFactory factory);
    
    /**
     * Method called to create actual usable per-deserialization
     * context instance.
     */
    public abstract DefaultDeserializationContext createInstance(
            DeserializationConfig config, JsonParser p, InjectableValues values);

    public abstract DefaultDeserializationContext createDummyInstance(
            DeserializationConfig config);
    
    /*
    /**********************************************************
    /* Extended API, read methods
    /**********************************************************
     */

    public Object readRootValue(JsonParser p, JavaType valueType,
            JsonDeserializer<Object> deser, Object valueToUpdate)
        throws IOException
    {
        if (_config.useRootWrapping()) {
            return _unwrapAndDeserialize(p, valueType, deser, valueToUpdate);
        }
        if (valueToUpdate == null) {
            return deser.deserialize(p, this);
        }
        return deser.deserialize(p, this, valueToUpdate);
    }

    protected Object _unwrapAndDeserialize(JsonParser p,
            JavaType rootType, JsonDeserializer<Object> deser,
            Object valueToUpdate)
        throws IOException
    {
        PropertyName expRootName = _config.findRootName(rootType);
        // 12-Jun-2015, tatu: Should try to support namespaces etc but...
        String expSimpleName = expRootName.getSimpleName();
        if (p.currentToken() != JsonToken.START_OBJECT) {
            reportWrongTokenException(rootType, JsonToken.START_OBJECT,
                    "Current token not START_OBJECT (needed to unwrap root name %s), but %s",
                    ClassUtil.name(expSimpleName), p.currentToken());
        }
        if (p.nextToken() != JsonToken.FIELD_NAME) {
            reportWrongTokenException(rootType, JsonToken.FIELD_NAME,
                    "Current token not FIELD_NAME (to contain expected root name %s), but %s",
                    ClassUtil.name(expSimpleName), p.currentToken());
        }
        String actualName = p.currentName();
        if (!expSimpleName.equals(actualName)) {
            reportPropertyInputMismatch(rootType, actualName,
"Root name (%s) does not match expected (%s) for type %s",
ClassUtil.name(actualName), ClassUtil.name(expSimpleName), ClassUtil.getTypeDescription(rootType));
        }
        // ok, then move to value itself....
        p.nextToken();
        final Object result;
        if (valueToUpdate == null) {
            result = deser.deserialize(p, this);
        } else {
            result = deser.deserialize(p, this, valueToUpdate);
        }
        // and last, verify that we now get matching END_OBJECT
        if (p.nextToken() != JsonToken.END_OBJECT) {
            reportWrongTokenException(rootType, JsonToken.END_OBJECT,
"Current token not END_OBJECT (to match wrapper object with root name %s), but %s",
ClassUtil.name(expSimpleName), p.currentToken());
        }
        return result;
    }

    /*
    /**********************************************************
    /* And then the concrete implementation class
    /**********************************************************
     */

    /**
     * Actual full concrete implementation
     */
    public final static class Impl extends DefaultDeserializationContext
    {
        private static final long serialVersionUID = 1L;

        /**
         * Default constructor for a blueprint object, which will use the standard
         * {@link DeserializerCache}, given factory.
         */
        public Impl(DeserializerFactory df) {
            super(df, null);
        }

        private Impl(Impl src,
                DeserializationConfig config, JsonParser p, InjectableValues values) {
            super(src, config, p, values);
        }

        private Impl(Impl src) { super(src); }

        private Impl(Impl src, DeserializerFactory factory) {
            super(src, factory);
        }

        private Impl(Impl src, DeserializationConfig config) {
            super(src, config);
        }

        @Override
        public DefaultDeserializationContext copy() {
            ClassUtil.verifyMustOverride(Impl.class, this, "copy");
            return new Impl(this);
        }

        @Override
        public DefaultDeserializationContext createInstance(DeserializationConfig config,
                JsonParser p, InjectableValues values) {
            return new Impl(this, config, p, values);
        }

        @Override
        public DefaultDeserializationContext createDummyInstance(DeserializationConfig config) {
            // need to be careful to create "real", not blue-print, instance
            return new Impl(this, config);
        }

        @Override
        public DefaultDeserializationContext with(DeserializerFactory factory) {
            return new Impl(this, factory);
        }
    }
}

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