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/impl/CreatorCollector.java

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

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

import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.cfg.MapperConfig;
import com.fasterxml.jackson.databind.deser.SettableBeanProperty;
import com.fasterxml.jackson.databind.deser.ValueInstantiator;
import com.fasterxml.jackson.databind.deser.std.StdValueInstantiator;
import com.fasterxml.jackson.databind.introspect.*;
import com.fasterxml.jackson.databind.util.ClassUtil;

/**
 * Container class for storing information on creators (based on annotations,
 * visibility), to be able to build actual {@code ValueInstantiator} later on.
 */
public class CreatorCollector
{
    protected final static int C_DEFAULT = 0;
    protected final static int C_STRING = 1;
    protected final static int C_INT = 2;
    protected final static int C_LONG = 3;
    protected final static int C_BIG_INTEGER = 4;
    protected final static int C_DOUBLE = 5;
    protected final static int C_BIG_DECIMAL = 6;
    protected final static int C_BOOLEAN = 7;
    protected final static int C_DELEGATE = 8;
    protected final static int C_PROPS = 9;
    protected final static int C_ARRAY_DELEGATE = 10;

    protected final static String[] TYPE_DESCS = new String[] { "default",
            "from-String", "from-int", "from-long", "from-big-integer", "from-double",
            "from-big-decimal", "from-boolean", "delegate", "property-based", "array-delegate"
    };

    /**
     * Type of bean being created
     */
    protected final BeanDescription _beanDesc;

    protected final boolean _canFixAccess;

    /**
     * @since 2.7
     */
    protected final boolean _forceAccess;

    /**
     * Set of creators we have collected so far
     * 
     * @since 2.5
     */
    protected final AnnotatedWithParams[] _creators = new AnnotatedWithParams[11];

    /**
     * Bitmask of creators that were explicitly marked as creators; false for
     * auto-detected (ones included base on naming and/or visibility, not
     * annotation)
     *
     * @since 2.5
     */
    protected int _explicitCreators = 0;

    protected boolean _hasNonDefaultCreator = false;

    // when there are injectable values along with delegate:
    protected SettableBeanProperty[] _delegateArgs;

    protected SettableBeanProperty[] _arrayDelegateArgs;

    protected SettableBeanProperty[] _propertyBasedArgs;

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

    public CreatorCollector(BeanDescription beanDesc, MapperConfig<?> config) {
        _beanDesc = beanDesc;
        _canFixAccess = config.canOverrideAccessModifiers();
        _forceAccess = config
                .isEnabled(MapperFeature.OVERRIDE_PUBLIC_ACCESS_MODIFIERS);
    }

    public ValueInstantiator constructValueInstantiator(DeserializationContext ctxt)
        throws JsonMappingException
    {
        final DeserializationConfig config = ctxt.getConfig();
        final JavaType delegateType = _computeDelegateType(ctxt,
                _creators[C_DELEGATE], _delegateArgs);
        final JavaType arrayDelegateType = _computeDelegateType(ctxt,
                _creators[C_ARRAY_DELEGATE], _arrayDelegateArgs);
        final JavaType type = _beanDesc.getType();

        StdValueInstantiator inst = new StdValueInstantiator(config, type);
        inst.configureFromObjectSettings(_creators[C_DEFAULT], _creators[C_DELEGATE],
                delegateType, _delegateArgs, _creators[C_PROPS],
                _propertyBasedArgs);
        inst.configureFromArraySettings(_creators[C_ARRAY_DELEGATE],
                arrayDelegateType, _arrayDelegateArgs);
        inst.configureFromStringCreator(_creators[C_STRING]);
        inst.configureFromIntCreator(_creators[C_INT]);
        inst.configureFromLongCreator(_creators[C_LONG]);
        inst.configureFromBigIntegerCreator(_creators[C_BIG_INTEGER]);
        inst.configureFromDoubleCreator(_creators[C_DOUBLE]);
        inst.configureFromBigDecimalCreator(_creators[C_BIG_DECIMAL]);
        inst.configureFromBooleanCreator(_creators[C_BOOLEAN]);
        return inst;
    }

    /*
    /**********************************************************
    /* Setters
    /**********************************************************
     */

    /**
     * Method called to indicate the default creator: no-arguments constructor
     * or factory method that is called to instantiate a value before populating
     * it with data. Default creator is only used if no other creators are
     * indicated.
     * 
     * @param creator
     *            Creator method; no-arguments constructor or static factory
     *            method.
     */
    public void setDefaultCreator(AnnotatedWithParams creator) {
        _creators[C_DEFAULT] = _fixAccess(creator);
    }

    public void addStringCreator(AnnotatedWithParams creator, boolean explicit) {
        verifyNonDup(creator, C_STRING, explicit);
    }

    public void addIntCreator(AnnotatedWithParams creator, boolean explicit) {
        verifyNonDup(creator, C_INT, explicit);
    }

    public void addLongCreator(AnnotatedWithParams creator, boolean explicit) {
        verifyNonDup(creator, C_LONG, explicit);
    }

    public void addBigIntegerCreator(AnnotatedWithParams creator, boolean explicit) {
        verifyNonDup(creator, C_BIG_INTEGER, explicit);
    }

    public void addDoubleCreator(AnnotatedWithParams creator, boolean explicit) {
        verifyNonDup(creator, C_DOUBLE, explicit);
    }

    public void addBigDecimalCreator(AnnotatedWithParams creator, boolean explicit) {
        verifyNonDup(creator, C_BIG_DECIMAL, explicit);
    }

    public void addBooleanCreator(AnnotatedWithParams creator, boolean explicit) {
        verifyNonDup(creator, C_BOOLEAN, explicit);
    }

    public void addDelegatingCreator(AnnotatedWithParams creator,
            boolean explicit, SettableBeanProperty[] injectables,
            int delegateeIndex)
    {
        if (creator.getParameterType(delegateeIndex).isCollectionLikeType()) {
            if (verifyNonDup(creator, C_ARRAY_DELEGATE, explicit)) {
                _arrayDelegateArgs = injectables;
            }
        } else {
            if (verifyNonDup(creator, C_DELEGATE, explicit)) {
                _delegateArgs = injectables;
            }
        }
    }

    public void addPropertyCreator(AnnotatedWithParams creator,
            boolean explicit, SettableBeanProperty[] properties)
    {
        if (verifyNonDup(creator, C_PROPS, explicit)) {
            // Better ensure we have no duplicate names either...
            if (properties.length > 1) {
                HashMap<String, Integer> names = new HashMap<String, Integer>();
                for (int i = 0, len = properties.length; i < len; ++i) {
                    String name = properties[i].getName();
                    // Need to consider Injectables, which may not have
                    // a name at all, and need to be skipped
                    if (name.isEmpty() && (properties[i].getInjectableValueId() != null)) {
                        continue;
                    }
                    Integer old = names.put(name, Integer.valueOf(i));
                    if (old != null) {
                        throw new IllegalArgumentException(String.format(
                                "Duplicate creator property \"%s\" (index %s vs %d) for type %s ",
                                name, old, i, ClassUtil.nameOf(_beanDesc.getBeanClass())));
                    }
                }
            }
            _propertyBasedArgs = properties;
        }
    }

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

    /**
     * @since 2.1
     */
    public boolean hasDefaultCreator() {
        return _creators[C_DEFAULT] != null;
    }

    /**
     * @since 2.6
     */
    public boolean hasDelegatingCreator() {
        return _creators[C_DELEGATE] != null;
    }

    /**
     * @since 2.6
     */
    public boolean hasPropertyBasedCreator() {
        return _creators[C_PROPS] != null;
    }

    /*
    /**********************************************************
    /* Helper methods
    /**********************************************************
     */

    private JavaType _computeDelegateType(DeserializationContext ctxt,
            AnnotatedWithParams creator, SettableBeanProperty[] delegateArgs)
        throws JsonMappingException
    {
        if (!_hasNonDefaultCreator || (creator == null)) {
            return null;
        }
        // need to find type...
        int ix = 0;
        if (delegateArgs != null) {
            for (int i = 0, len = delegateArgs.length; i < len; ++i) {
                if (delegateArgs[i] == null) { // marker for delegate itself
                    ix = i;
                    break;
                }
            }
        }
        final DeserializationConfig config = ctxt.getConfig();

        // 03-May-2018, tatu: need to check possible annotation-based
        //   custom deserializer [databind#2012],
        //   type refinement(s) [databind#2016]. 
        JavaType baseType = creator.getParameterType(ix);
        AnnotationIntrospector intr = config.getAnnotationIntrospector();
        if (intr != null) {
            AnnotatedParameter delegate = creator.getParameter(ix);
            
            // First: custom deserializer(s):
            Object deserDef = intr.findDeserializer(delegate);
            if (deserDef != null) {
                JsonDeserializer<Object> deser = ctxt.deserializerInstance(delegate, deserDef);
                baseType = baseType.withValueHandler(deser);
            } else {
                // Second: type refinement(s), if no explicit deserializer was located
                baseType = intr.refineDeserializationType(config,
                        delegate, baseType);
            }
        }
        return baseType;
    }

    private <T extends AnnotatedMember> T _fixAccess(T member) {
        if (member != null && _canFixAccess) {
            ClassUtil.checkAndFixAccess((Member) member.getAnnotated(),
                    _forceAccess);
        }
        return member;
    }

    /**
     * @return True if specified Creator is to be used
     */
    protected boolean verifyNonDup(AnnotatedWithParams newOne, int typeIndex, boolean explicit)
    {
        final int mask = (1 << typeIndex);
        _hasNonDefaultCreator = true;
        AnnotatedWithParams oldOne = _creators[typeIndex];
        // already had an explicitly marked one?
        if (oldOne != null) {
            boolean verify;
            if ((_explicitCreators & mask) != 0) { // already had explicitly annotated, leave as-is
                // but skip, if new one not annotated
                if (!explicit) {
                    return false;
                }
                // both explicit: verify
                verify = true;
            } else {
                // otherwise only verify if neither explicitly annotated.
                verify = !explicit;
            }

            // one more thing: ok to override in sub-class
            // 23-Feb-2021, tatu: Second check is for case of static factory vs constructor,
            //    which is handled by caller, presumably.
            //    Removing it would fail one test (in case interested).
            if (verify && (oldOne.getClass() == newOne.getClass())) {
                // [databind#667]: avoid one particular class of bogus problems
                final Class<?> oldType = oldOne.getRawParameterType(0);
                final Class<?> newType = newOne.getRawParameterType(0);

                if (oldType == newType) {
                    // 13-Jul-2016, tatu: One more thing to check; since Enum classes
                    //   always have implicitly created `valueOf()`, let's resolve in
                    //   favor of other implicit creator (`fromString()`)
                    if (_isEnumValueOf(newOne)) {
                        return false; // ignore
                    }
                    if (_isEnumValueOf(oldOne)) {
                        ;
                    } else {
                        _reportDuplicateCreator(typeIndex, explicit, oldOne, newOne);
                    }
                }
                // otherwise, which one to choose?
                else if (newType.isAssignableFrom(oldType)) {
                    // new type less specific use old
                    return false;
                } else if (oldType.isAssignableFrom(newType)) {
                    // new type more specific, use it
                    ;
                    // 23-Feb-2021, tatu: due to [databind#3062], backwards-compatibility,
                    //   let's allow "primitive/Wrapper" case and tie-break in favor
                    //   of PRIMITIVE argument (null would never map to scalar creators,
                    //   and fundamentally all we need is a tie-breaker: up to caller to
                    //   annotate if wants the wrapper one)
                } else if (oldType.isPrimitive() != newType.isPrimitive()) {
                    // Prefer primitive one
                    if (oldType.isPrimitive()) {
                        return false;
                    }
                } else {
                    // 02-May-2020, tatu: Should this only result in exception if both
                    //   explicit? Doing so could lead to arbitrary choice between
                    //   multiple implicit creators tho?
                    _reportDuplicateCreator(typeIndex, explicit, oldOne, newOne);
                }
            }
        }
        if (explicit) {
            _explicitCreators |= mask;
        }
        _creators[typeIndex] = _fixAccess(newOne);
        return true;
    }

    // @since 2.12
    protected void _reportDuplicateCreator(int typeIndex, boolean explicit,
            AnnotatedWithParams oldOne, AnnotatedWithParams newOne) {
        throw new IllegalArgumentException(String.format(
                "Conflicting %s creators: already had %s creator %s, encountered another: %s",
                TYPE_DESCS[typeIndex],
                explicit ? "explicitly marked"
                        : "implicitly discovered",
                oldOne, newOne));
    }
    
    /**
     * Helper method for recognizing `Enum.valueOf()` factory method
     *
     * @since 2.8.1
     */
    protected boolean _isEnumValueOf(AnnotatedWithParams creator) {
        return ClassUtil.isEnumType(creator.getDeclaringClass())
                && "valueOf".equals(creator.getName());
    }
}

⏎ com/fasterxml/jackson/databind/deser/impl/CreatorCollector.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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