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/type/MapLikeType.java

package com.fasterxml.jackson.databind.type;

import java.lang.reflect.TypeVariable;
import java.util.*;

import com.fasterxml.jackson.databind.JavaType;

/**
 * Type that represents Map-like types; things that consist of key/value pairs
 * but that do not necessarily implement {@link java.util.Map}, but that do not
 * have enough introspection functionality to allow for some level of generic
 * handling. This specifically allows framework to check for configuration and
 * annotation settings used for Map types, and pass these to custom handlers
 * that may be more familiar with actual type.
 */
public class MapLikeType extends TypeBase {
    private static final long serialVersionUID = 1L;

    /**
     * Type of keys of Map.
     */
    protected final JavaType _keyType;

    /**
     * Type of values of Map.
     */
    protected final JavaType _valueType;

    /*
    /**********************************************************
    * Life-cycle
    /**********************************************************
     */

    protected MapLikeType(Class<?> mapType, TypeBindings bindings,
            JavaType superClass, JavaType[] superInts, JavaType keyT,
            JavaType valueT, Object valueHandler, Object typeHandler,
            boolean asStatic) {
        super(mapType, bindings, superClass, superInts, keyT.hashCode()
                ^ valueT.hashCode(), valueHandler, typeHandler, asStatic);
        _keyType = keyT;
        _valueType = valueT;
    }

    /**
     * @since 2.7
     */
    protected MapLikeType(TypeBase base, JavaType keyT, JavaType valueT) {
        super(base);
        _keyType = keyT;
        _valueType = valueT;
    }

    /**
     * Factory method that can be used to "upgrade" a basic type into
     * collection-like one; usually done via {@link TypeModifier}
     *
     * @since 2.7
     */
    public static MapLikeType upgradeFrom(JavaType baseType, JavaType keyT,
            JavaType valueT) {
        // 19-Oct-2015, tatu: Not sure if and how other types could be used as
        // base;
        // will cross that bridge if and when need be
        if (baseType instanceof TypeBase) {
            return new MapLikeType((TypeBase) baseType, keyT, valueT);
        }
        throw new IllegalArgumentException(
                "Cannot upgrade from an instance of " + baseType.getClass());
    }

    @Deprecated
    // since 2.7; remove from 2.8
    public static MapLikeType construct(Class<?> rawType, JavaType keyT,
            JavaType valueT) {
        // First: may need to fabricate TypeBindings (needed for refining into
        // concrete collection types, as per [databind#1102])
        TypeVariable<?>[] vars = rawType.getTypeParameters();
        TypeBindings bindings;
        if ((vars == null) || (vars.length != 2)) {
            bindings = TypeBindings.emptyBindings();
        } else {
            bindings = TypeBindings.create(rawType, keyT, valueT);
        }
        return new MapLikeType(rawType, bindings, _bogusSuperClass(rawType),
                null, keyT, valueT, null, null, false);
    }

    @Deprecated
    // since 2.7
    @Override
    protected JavaType _narrow(Class<?> subclass) {
        return new MapLikeType(subclass, _bindings, _superClass,
                _superInterfaces, _keyType, _valueType, _valueHandler,
                _typeHandler, _asStatic);
    }

    /**
     * @since 2.7
     */
    public MapLikeType withKeyType(JavaType keyType) {
        if (keyType == _keyType) {
            return this;
        }
        return new MapLikeType(_class, _bindings, _superClass,
                _superInterfaces, keyType, _valueType, _valueHandler,
                _typeHandler, _asStatic);
    }

    @Override
    public JavaType withContentType(JavaType contentType) {
        if (_valueType == contentType) {
            return this;
        }
        return new MapLikeType(_class, _bindings, _superClass,
                _superInterfaces, _keyType, contentType, _valueHandler,
                _typeHandler, _asStatic);
    }

    @Override
    public MapLikeType withTypeHandler(Object h) {
        return new MapLikeType(_class, _bindings, _superClass,
                _superInterfaces, _keyType, _valueType, _valueHandler, h,
                _asStatic);
    }

    @Override
    public MapLikeType withContentTypeHandler(Object h) {
        return new MapLikeType(_class, _bindings, _superClass,
                _superInterfaces, _keyType, _valueType.withTypeHandler(h),
                _valueHandler, _typeHandler, _asStatic);
    }

    @Override
    public MapLikeType withValueHandler(Object h) {
        return new MapLikeType(_class, _bindings, _superClass,
                _superInterfaces, _keyType, _valueType, h, _typeHandler,
                _asStatic);
    }

    @Override
    public MapLikeType withContentValueHandler(Object h) {
        return new MapLikeType(_class, _bindings, _superClass,
                _superInterfaces, _keyType, _valueType.withValueHandler(h),
                _valueHandler, _typeHandler, _asStatic);
    }

    @Override
    public JavaType withHandlersFrom(JavaType src) {
        JavaType type = super.withHandlersFrom(src);
        JavaType srcKeyType = src.getKeyType();
        // "withKeyType()" not part of JavaType, hence must verify:
        if (type instanceof MapLikeType) {
            if (srcKeyType != null) {
                JavaType ct = _keyType.withHandlersFrom(srcKeyType);
                if (ct != _keyType) {
                    type = ((MapLikeType) type).withKeyType(ct);
                }
            }
        }
        JavaType srcCt = src.getContentType();
        if (srcCt != null) {
            JavaType ct = _valueType.withHandlersFrom(srcCt);
            if (ct != _valueType) {
                type = type.withContentType(ct);
            }
        }
        return type;
    }

    @Override
    public MapLikeType withStaticTyping() {
        if (_asStatic) {
            return this;
        }
        return new MapLikeType(_class, _bindings, _superClass,
                _superInterfaces, _keyType, _valueType.withStaticTyping(),
                _valueHandler, _typeHandler, true);
    }

    @Override
    public JavaType refine(Class<?> rawType, TypeBindings bindings,
            JavaType superClass, JavaType[] superInterfaces) {
        return new MapLikeType(rawType, bindings, superClass, superInterfaces,
                _keyType, _valueType, _valueHandler, _typeHandler, _asStatic);
    }

    @Override
    protected String buildCanonicalName() {
        StringBuilder sb = new StringBuilder();
        sb.append(_class.getName());
        // 10-Apr-2021, tatu: [databind#3108] Ensure we have at least nominally
        //   compatible type declaration (weak guarantee but better than nothing)
        if ((_keyType != null) && _hasNTypeParameters(2)) {
            sb.append('<');
            sb.append(_keyType.toCanonical());
            sb.append(',');
            sb.append(_valueType.toCanonical());
            sb.append('>');
        }
        return sb.toString();
    }

    /*
    /**********************************************************
    /* Public API
    /**********************************************************
     */

    @Override
    public boolean isContainerType() {
        return true;
    }

    @Override
    public boolean isMapLikeType() {
        return true;
    }

    @Override
    public JavaType getKeyType() {
        return _keyType;
    }

    @Override
    public JavaType getContentType() {
        return _valueType;
    }

    @Override
    public Object getContentValueHandler() {
        return _valueType.getValueHandler();
    }

    @Override
    public Object getContentTypeHandler() {
        return _valueType.getTypeHandler();
    }

    @Override
    public boolean hasHandlers() {
        return super.hasHandlers() || _valueType.hasHandlers()
                || _keyType.hasHandlers();
    }

    @Override
    public StringBuilder getErasedSignature(StringBuilder sb) {
        return _classSignature(_class, sb, true);
    }

    @Override
    public StringBuilder getGenericSignature(StringBuilder sb) {
        _classSignature(_class, sb, false);
        sb.append('<');
        _keyType.getGenericSignature(sb);
        _valueType.getGenericSignature(sb);
        sb.append(">;");
        return sb;
    }

    /*
    /**********************************************************
    /* Extended API
    /**********************************************************
     */

    public MapLikeType withKeyTypeHandler(Object h) {
        return new MapLikeType(_class, _bindings, _superClass,
                _superInterfaces, _keyType.withTypeHandler(h), _valueType,
                _valueHandler, _typeHandler, _asStatic);
    }

    public MapLikeType withKeyValueHandler(Object h) {
        return new MapLikeType(_class, _bindings, _superClass,
                _superInterfaces, _keyType.withValueHandler(h), _valueType,
                _valueHandler, _typeHandler, _asStatic);
    }

    /**
     * Method that can be used for checking whether this type is a "real"
     * Collection type; meaning whether it represents a parameterized subtype of
     * {@link java.util.Collection} or just something that acts like one.
     *
     * @deprecated Since 2.12 just use instanceof 
     */
    @Deprecated // since 2.12 use assignment checks
    public boolean isTrueMapType() {
        return Map.class.isAssignableFrom(_class);
    }

    /*
    /**********************************************************
    /* Standard methods
    /**********************************************************
     */

    @Override
    public String toString() {
        return String.format("[map-like type; class %s, %s -> %s]",
                _class.getName(), _keyType, _valueType);
    }

    @Override
    public boolean equals(Object o) {
        if (o == this) return true;
        if (o == null) return false;
        if (o.getClass() != getClass()) return false;

        MapLikeType other = (MapLikeType) o;
        return (_class == other._class) && _keyType.equals(other._keyType)
                && _valueType.equals(other._valueType);
    }
}

⏎ com/fasterxml/jackson/databind/type/MapLikeType.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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