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/jsontype/impl/ClassNameIdResolver.java

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

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

import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.cfg.MapperConfig;
import com.fasterxml.jackson.databind.jsontype.PolymorphicTypeValidator;
import com.fasterxml.jackson.databind.type.TypeFactory;
import com.fasterxml.jackson.databind.util.ClassUtil;

/**
 * {@link com.fasterxml.jackson.databind.jsontype.TypeIdResolver} implementation
 * that converts between fully-qualified
 * Java class names and (JSON) Strings.
 */
public class ClassNameIdResolver
    extends TypeIdResolverBase
{
    private final static String JAVA_UTIL_PKG = "java.util.";

    protected final PolymorphicTypeValidator _subTypeValidator;

    /**
     * @deprecated Since 2.10 use variant that takes {@link PolymorphicTypeValidator}
     */
    @Deprecated
    protected ClassNameIdResolver(JavaType baseType, TypeFactory typeFactory) {
        this(baseType, typeFactory, LaissezFaireSubTypeValidator.instance);
    }

    /**
     * @since 2.10
     */
    public ClassNameIdResolver(JavaType baseType, TypeFactory typeFactory,
            PolymorphicTypeValidator ptv) {
        super(baseType, typeFactory);
        _subTypeValidator = ptv;
    }

    public static ClassNameIdResolver construct(JavaType baseType, MapperConfig<?> config,
            PolymorphicTypeValidator ptv) {
        return new ClassNameIdResolver(baseType, config.getTypeFactory(), ptv);
    }

    @Override
    public JsonTypeInfo.Id getMechanism() { return JsonTypeInfo.Id.CLASS; }

    public void registerSubtype(Class<?> type, String name) {
        // not used with class name - based resolvers
    }

    @Override
    public String idFromValue(Object value) {
        return _idFrom(value, value.getClass(), _typeFactory);
    }

    @Override
    public String idFromValueAndType(Object value, Class<?> type) {
        return _idFrom(value, type, _typeFactory);
    }

    @Override
    public JavaType typeFromId(DatabindContext context, String id) throws IOException {
        return _typeFromId(id, context);
    }

    protected JavaType _typeFromId(String id, DatabindContext ctxt) throws IOException
    {
        // 24-Apr-2019, tatu: [databind#2195] validate as well as resolve:
        JavaType t = ctxt.resolveAndValidateSubType(_baseType, id, _subTypeValidator);
        if (t == null) {
            if (ctxt instanceof DeserializationContext) {
                // First: we may have problem handlers that can deal with it?
                return ((DeserializationContext) ctxt).handleUnknownTypeId(_baseType, id, this, "no such class found");
            }
            // ... meaning that we really should never get here.
        }
        return t;
    }

    /*
    /**********************************************************
    /* Internal methods
    /**********************************************************
     */

    protected String _idFrom(Object value, Class<?> cls, TypeFactory typeFactory)
    {
        // Need to ensure that "enum subtypes" work too
        if (ClassUtil.isEnumType(cls)) {
            // 29-Sep-2019, tatu: `Class.isEnum()` only returns true for main declaration,
            //   but NOT from sub-class thereof (extending individual values). This
            //   is why additional resolution is needed: we want class that contains
            //   enumeration instances.
            if (!cls.isEnum()) {
                // and this parent would then have `Enum.class` as its parent:
                cls = cls.getSuperclass();
            }
        }
        String str = cls.getName();
        if (str.startsWith(JAVA_UTIL_PKG)) {
            // 25-Jan-2009, tatu: There are some internal classes that we cannot access as is.
            //     We need better mechanism; for now this has to do...

            // Enum sets and maps are problematic since we MUST know type of
            // contained enums, to be able to deserialize.
            // In addition, EnumSet is not a concrete type either
            if (value instanceof EnumSet<?>) { // Regular- and JumboEnumSet...
                Class<?> enumClass = ClassUtil.findEnumType((EnumSet<?>) value);
                // not optimal: but EnumSet is not a customizable type so this is sort of ok
               str = typeFactory.constructCollectionType(EnumSet.class, enumClass).toCanonical();
            } else if (value instanceof EnumMap<?,?>) {
                Class<?> enumClass = ClassUtil.findEnumType((EnumMap<?,?>) value);
                Class<?> valueClass = Object.class;
                // not optimal: but EnumMap is not a customizable type so this is sort of ok
                str = typeFactory.constructMapType(EnumMap.class, enumClass, valueClass).toCanonical();
            }
            // 10-Jan-2018, tatu: Up until 2.9.4 we used to have other conversions for `Collections.xxx()`
            //    and `Arrays.asList(...)`; but it was changed to be handled on receiving end instead
        } else if (str.indexOf('$') >= 0) {
            /* Other special handling may be needed for inner classes,
             * The best way to handle would be to find 'hidden' constructor; pass parent
             * value etc (which is actually done for non-anonymous static classes!),
             * but that is just not possible due to various things. So, we will instead
             * try to generalize type into something we will be more likely to be able
             * construct.
             */
            Class<?> outer = ClassUtil.getOuterClass(cls);
            if (outer != null) {
                // one more check: let's actually not worry if the declared static type is
                // non-static as well; if so, deserializer does have a chance at figuring it all out.
                Class<?> staticType = _baseType.getRawClass();
                if (ClassUtil.getOuterClass(staticType) == null) {
                    // Is this always correct? Seems like it should be...
                    cls = _baseType.getRawClass();
                    str = cls.getName();
                }
            }
        }
        return str;
    }

    @Override
    public String getDescForKnownTypeIds() {
        return "class name used as type id";
    }
}

⏎ com/fasterxml/jackson/databind/jsontype/impl/ClassNameIdResolver.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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