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/StdTypeResolverBuilder.java

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

import java.util.Collection;

import com.fasterxml.jackson.annotation.JsonTypeInfo;

import com.fasterxml.jackson.databind.DeserializationConfig;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.MapperFeature;
import com.fasterxml.jackson.databind.SerializationConfig;
import com.fasterxml.jackson.databind.annotation.NoClass;
import com.fasterxml.jackson.databind.cfg.MapperConfig;
import com.fasterxml.jackson.databind.jsontype.*;
import com.fasterxml.jackson.databind.util.ClassUtil;

/**
 * Default {@link TypeResolverBuilder} implementation.
 */
public class StdTypeResolverBuilder
    implements TypeResolverBuilder<StdTypeResolverBuilder>
{
    // Configuration settings:

    protected JsonTypeInfo.Id _idType;

    protected JsonTypeInfo.As _includeAs;

    protected String _typeProperty;

    /**
     * Whether type id should be exposed to deserializers or not
     */
    protected boolean _typeIdVisible = false;
    
    /**
     * Default class to use in case type information is not available
     * or is broken.
     */
    protected Class<?> _defaultImpl;
    
    // Objects
    
    protected TypeIdResolver _customIdResolver;
    
    /*
    /**********************************************************
    /* Construction, initialization, actual building
    /**********************************************************
     */

    public StdTypeResolverBuilder() { }

    /**
     * @since 2.9
     */
    protected StdTypeResolverBuilder(JsonTypeInfo.Id idType,
            JsonTypeInfo.As idAs, String propName) {
        _idType = idType;
        _includeAs = idAs;
        _typeProperty = propName;
    }

    /**
     * Copy-constructor
     *
     * @since 2.13
     */
    protected StdTypeResolverBuilder(StdTypeResolverBuilder base,
            Class<?> defaultImpl)
    {
        _idType = base._idType;
        _includeAs = base._includeAs;
        _typeProperty = base._typeProperty;
        _typeIdVisible = base._typeIdVisible;
        _customIdResolver = base._customIdResolver;

        _defaultImpl = defaultImpl;
    }

    public static StdTypeResolverBuilder noTypeInfoBuilder() {
        return new StdTypeResolverBuilder().init(JsonTypeInfo.Id.NONE, null);
    }

    @Override
    public StdTypeResolverBuilder init(JsonTypeInfo.Id idType, TypeIdResolver idRes)
    {
        // sanity checks
        if (idType == null) {
            throw new IllegalArgumentException("idType cannot be null");
        }
        _idType = idType;
        _customIdResolver = idRes;
        // Let's also initialize property name as per idType default
        _typeProperty = idType.getDefaultPropertyName();
        return this;
    }

    @Override
    public TypeSerializer buildTypeSerializer(SerializationConfig config,
            JavaType baseType, Collection<NamedType> subtypes)
    {
        if (_idType == JsonTypeInfo.Id.NONE) { return null; }
        // 03-Oct-2016, tatu: As per [databind#1395] better prevent use for primitives,
        //    regardless of setting
        if (baseType.isPrimitive()) {
            // 19-Jun-2020, tatu: But for [databind#2753], allow overriding
            if (!allowPrimitiveTypes(config, baseType)) {
                return null;
            }
        }

        TypeIdResolver idRes = idResolver(config, baseType, subTypeValidator(config),
                subtypes, true, false);

        if(_idType == JsonTypeInfo.Id.DEDUCTION) {
            // Deduction doesn't require a type property. We use EXISTING_PROPERTY with a name of <null> to drive this.
            return new AsExistingPropertyTypeSerializer(idRes, null, _typeProperty);
        }

        switch (_includeAs) {
        case WRAPPER_ARRAY:
            return new AsArrayTypeSerializer(idRes, null);
        case PROPERTY:
            return new AsPropertyTypeSerializer(idRes, null, _typeProperty);
        case WRAPPER_OBJECT:
            return new AsWrapperTypeSerializer(idRes, null);
        case EXTERNAL_PROPERTY:
            return new AsExternalTypeSerializer(idRes, null, _typeProperty);
        case EXISTING_PROPERTY:
        	// as per [#528]
        	return new AsExistingPropertyTypeSerializer(idRes, null, _typeProperty);
        }
        throw new IllegalStateException("Do not know how to construct standard type serializer for inclusion type: "+_includeAs);
    }

    // as per [#368]
    // removed when fix [#528]
    //private IllegalArgumentException _noExisting() {
    //    return new IllegalArgumentException("Inclusion type "+_includeAs+" not yet supported");
    //}

    @Override
    public TypeDeserializer buildTypeDeserializer(DeserializationConfig config,
            JavaType baseType, Collection<NamedType> subtypes)
    {
        if (_idType == JsonTypeInfo.Id.NONE) { return null; }
        // 03-Oct-2016, tatu: As per [databind#1395] better prevent use for primitives,
        //    regardless of setting
        if (baseType.isPrimitive()) {
            // 19-Jun-2020, tatu: But for [databind#2753], allow overriding
            if (!allowPrimitiveTypes(config, baseType)) {
                return null;
            }
        }

        // 27-Apr-2019, tatu: Part of [databind#2195]; must first check whether any subtypes
        //    of basetypes might be denied or allowed
        final PolymorphicTypeValidator subTypeValidator = verifyBaseTypeValidity(config, baseType);

        TypeIdResolver idRes = idResolver(config, baseType, subTypeValidator, subtypes, false, true);

        JavaType defaultImpl = defineDefaultImpl(config, baseType);

        if(_idType == JsonTypeInfo.Id.DEDUCTION) {
            // Deduction doesn't require an includeAs property
            return new AsDeductionTypeDeserializer(baseType, idRes, defaultImpl, config, subtypes);
        }

        // First, method for converting type info to type id:
        switch (_includeAs) {
        case WRAPPER_ARRAY:
            return new AsArrayTypeDeserializer(baseType, idRes,
                    _typeProperty, _typeIdVisible, defaultImpl);
        case PROPERTY:
        case EXISTING_PROPERTY: // as per [#528] same class as PROPERTY
            return new AsPropertyTypeDeserializer(baseType, idRes,
                    _typeProperty, _typeIdVisible, defaultImpl, _includeAs);
        case WRAPPER_OBJECT:
            return new AsWrapperTypeDeserializer(baseType, idRes,
                    _typeProperty, _typeIdVisible, defaultImpl);
        case EXTERNAL_PROPERTY:
            return new AsExternalTypeDeserializer(baseType, idRes,
                    _typeProperty, _typeIdVisible, defaultImpl);
        }
        throw new IllegalStateException("Do not know how to construct standard type serializer for inclusion type: "+_includeAs);
    }

    protected JavaType defineDefaultImpl(DeserializationConfig config, JavaType baseType)
    {
        if (_defaultImpl != null) {
            // 20-Mar-2016, tatu: It is important to do specialization go through
            //   TypeFactory to ensure proper resolution; with 2.7 and before, direct
            //   call to JavaType was used, but that cannot work reliably with 2.7
            // 20-Mar-2016, tatu: Can finally add a check for type compatibility BUT
            //   if so, need to add explicit checks for marker types. Not ideal, but
            //   seems like a reasonable compromise.
            if ((_defaultImpl == Void.class) || (_defaultImpl == NoClass.class)) {
                // 18-Sep-2021, tatu: This has specific meaning: these two markers will
                //    be used to conjure `null` value out of invalid type ids
                return config.getTypeFactory().constructType(_defaultImpl);
            }
            if (baseType.hasRawClass(_defaultImpl)) { // tiny optimization
                return baseType;
            }
            if (baseType.isTypeOrSuperTypeOf(_defaultImpl)) {
                // most common case with proper base type...
                return config.getTypeFactory()
                        .constructSpecializedType(baseType, _defaultImpl);
            }
            if (baseType.hasRawClass(_defaultImpl)) {
                return baseType;
            }
        }
        // use base type as default should always be used as the last choice.
        if (config.isEnabled(MapperFeature.USE_BASE_TYPE_AS_DEFAULT_IMPL)
               && !baseType.isAbstract()) {
            // still can not resolve by default impl, fall back to use base type as default impl
            return baseType;
        }
        return null;
    }

    /*
    /**********************************************************
    /* Construction, configuration
    /**********************************************************
     */

    @Override
    public StdTypeResolverBuilder inclusion(JsonTypeInfo.As includeAs) {
        if (includeAs == null) {
            throw new IllegalArgumentException("includeAs cannot be null");
        }
        _includeAs = includeAs;
        return this;
    }

    /**
     * Method for constructing an instance with specified type property name
     * (property name to use for type id when using "as-property" inclusion).
     */
    @Override
    public StdTypeResolverBuilder typeProperty(String typeIdPropName) {
        // ok to have null/empty; will restore to use defaults
        if (typeIdPropName == null || typeIdPropName.isEmpty()) {
            typeIdPropName = _idType.getDefaultPropertyName();
        }
        _typeProperty = typeIdPropName;
        return this;
    }

    @Override
    public StdTypeResolverBuilder defaultImpl(Class<?> defaultImpl) {
        _defaultImpl = defaultImpl;
        return this;
    }

    @Override
    public StdTypeResolverBuilder typeIdVisibility(boolean isVisible) {
        _typeIdVisible = isVisible;
        return this;
    }

    @Override
    public StdTypeResolverBuilder withDefaultImpl(Class<?> defaultImpl) {
        if (_defaultImpl == defaultImpl) {
            return this;
        }
        ClassUtil.verifyMustOverride(StdTypeResolverBuilder.class, this, "withDefaultImpl");

        // NOTE: MUST create new instance, NOT modify this instance
        return new StdTypeResolverBuilder(this, defaultImpl);
    }

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

    @Override public Class<?> getDefaultImpl() { return _defaultImpl; }

    public String getTypeProperty() { return _typeProperty; }
    public boolean isTypeIdVisible() { return _typeIdVisible; }

    /*
    /**********************************************************
    /* Internal/subtype factory methods
    /**********************************************************
     */

    /**
     * Helper method that will either return configured custom
     * type id resolver, or construct a standard resolver
     * given configuration.
     */
    protected TypeIdResolver idResolver(MapperConfig<?> config,
            JavaType baseType, PolymorphicTypeValidator subtypeValidator,
            Collection<NamedType> subtypes, boolean forSer, boolean forDeser)
    {
        // Custom id resolver?
        if (_customIdResolver != null) { return _customIdResolver; }
        if (_idType == null) throw new IllegalStateException("Cannot build, 'init()' not yet called");
        switch (_idType) {
        case DEDUCTION: // Deduction produces class names to be resolved
        case CLASS:
            return ClassNameIdResolver.construct(baseType, config, subtypeValidator);
        case MINIMAL_CLASS:
            return MinimalClassNameIdResolver.construct(baseType, config, subtypeValidator);
        case NAME:
            return TypeNameIdResolver.construct(config, baseType, subtypes, forSer, forDeser);
        case NONE: // hmmh. should never get this far with 'none'
            return null;
        case CUSTOM: // need custom resolver...
        }
        throw new IllegalStateException("Do not know how to construct standard type id resolver for idType: "+_idType);
    }

    /*
    /**********************************************************
    /* Internal/subtype factory methods
    /**********************************************************
     */

    /**
     * Overridable helper method for determining actual validator to use when constructing
     * type serializers and type deserializers.
     *<p>
     * Default implementation simply uses one configured and accessible using
     * {@link MapperConfig#getPolymorphicTypeValidator()}.
     *
     * @since 2.10
     */
    public PolymorphicTypeValidator subTypeValidator(MapperConfig<?> config) {
        return config.getPolymorphicTypeValidator();
    }
    
    /**
     * Helper method called to check that base type is valid regarding possible constraints
     * on basetype/subtype combinations allowed for polymorphic type handling.
     * Currently limits are verified for class name - based methods only.
     *
     * @since 2.10
     */
    protected PolymorphicTypeValidator verifyBaseTypeValidity(MapperConfig<?> config,
            JavaType baseType)
    {
        final PolymorphicTypeValidator ptv = subTypeValidator(config);
        if (_idType == JsonTypeInfo.Id.CLASS || _idType == JsonTypeInfo.Id.MINIMAL_CLASS) {
            final PolymorphicTypeValidator.Validity validity = ptv.validateBaseType(config, baseType);
            // If no subtypes are legal (that is, base type itself is invalid), indicate problem
            if (validity == PolymorphicTypeValidator.Validity.DENIED) {
                return reportInvalidBaseType(config, baseType, ptv);
            }
            // If there's indication that any and all subtypes are fine, replace validator itself:
            if (validity == PolymorphicTypeValidator.Validity.ALLOWED) {
                return LaissezFaireSubTypeValidator.instance;
            }
            // otherwise just return validator, is to be called for each distinct type
        }
        return ptv;
    }

    /**
     * @since 2.10
     */
    protected PolymorphicTypeValidator reportInvalidBaseType(MapperConfig<?> config,
            JavaType baseType, PolymorphicTypeValidator ptv)
    {
        throw new IllegalArgumentException(String.format(
"Configured `PolymorphicTypeValidator` (of type %s) denied resolution of all subtypes of base type %s",
                        ClassUtil.classNameOf(ptv), ClassUtil.classNameOf(baseType.getRawClass()))
        );
    }

    /*
    /**********************************************************
    /* Overridable helper methods
    /**********************************************************
     */

    /**
     * Overridable helper method that is called to determine whether type serializers
     * and type deserializers may be created even if base type is Java {@code primitive}
     * type.
     * Default implementation simply returns {@code false} (since primitive types can not
     * be sub-classed, are never polymorphic) but custom implementations
     * may change the logic for some special cases.
     *
     * @param config Currently active configuration
     * @param baseType Primitive base type for property being handled
     *
     * @return True if type (de)serializer may be created even if base type is Java
     *    {@code primitive} type; false if not
     *
     * @since 2.11.1
     */
    protected boolean allowPrimitiveTypes(MapperConfig<?> config,
            JavaType baseType) {
        return false;
    }
}

⏎ com/fasterxml/jackson/databind/jsontype/impl/StdTypeResolverBuilder.java

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