Jackson is "the Java JSON library" or "the best JSON parser for Java". Or simply as "JSON for Java".

Jackson Annotations Source Code files are provided in the source packge (jackson-annotations-2.12.4-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Annotations Source Code below:

⏎ com/fasterxml/jackson/databind/deser/SettableAnyProperty.java

package com.fasterxml.jackson.databind.deser;

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

import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.deser.impl.ReadableObjectId.Referring;
import com.fasterxml.jackson.databind.introspect.AnnotatedField;
import com.fasterxml.jackson.databind.introspect.AnnotatedMember;
import com.fasterxml.jackson.databind.introspect.AnnotatedMethod;
import com.fasterxml.jackson.databind.jsontype.TypeDeserializer;
import com.fasterxml.jackson.databind.util.ClassUtil;

/**
 * Class that represents a "wildcard" set method which can be used
 * to generically set values of otherwise unmapped (aka "unknown")
 * properties read from Json content.
 *<p>
 * !!! Note: might make sense to refactor to share some code
 * with {@link SettableBeanProperty}?
 */
public class SettableAnyProperty
    implements java.io.Serializable
{
    private static final long serialVersionUID = 1L;
    
    /**
     * Method used for setting "any" properties, along with annotation
     * information. Retained to allow contextualization of any properties.
     */
    protected final BeanProperty _property;

    /**
     * Annotated variant is needed for JDK serialization only
     */
    final protected AnnotatedMember _setter;

    final boolean _setterIsField;
    
    protected final JavaType _type;

    protected JsonDeserializer<Object> _valueDeserializer;

    protected final TypeDeserializer _valueTypeDeserializer;

    /**
     * @since 2.9
     */
    protected final KeyDeserializer _keyDeserializer;

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

    public SettableAnyProperty(BeanProperty property, AnnotatedMember setter, JavaType type,
            KeyDeserializer keyDeser,
            JsonDeserializer<Object> valueDeser, TypeDeserializer typeDeser)
    {
        _property = property;
        _setter = setter;
        _type = type;
        _valueDeserializer = valueDeser;
        _valueTypeDeserializer = typeDeser;
        _keyDeserializer = keyDeser;
        _setterIsField = setter instanceof AnnotatedField;
    }

    @Deprecated // since 2.9
    public SettableAnyProperty(BeanProperty property, AnnotatedMember setter, JavaType type,
            JsonDeserializer<Object> valueDeser, TypeDeserializer typeDeser)
    {
        this(property, setter, type, null, valueDeser, typeDeser);
    }

    public SettableAnyProperty withValueDeserializer(JsonDeserializer<Object> deser) {
        return new SettableAnyProperty(_property, _setter, _type,
                _keyDeserializer, deser, _valueTypeDeserializer);
    }

    public void fixAccess(DeserializationConfig config) {
        _setter.fixAccess(
                config.isEnabled(MapperFeature.OVERRIDE_PUBLIC_ACCESS_MODIFIERS));
    }

    /*
    /**********************************************************
    /* JDK serialization handling
    /**********************************************************
     */

    /**
     * Need to define this to verify that we retain actual Method reference
     */
    Object readResolve() {
        // sanity check...
        if (_setter == null || _setter.getAnnotated() == null) {
            throw new IllegalArgumentException("Missing method (broken JDK (de)serialization?)");
        }
        return this;
    }
    
    /*
    /**********************************************************
    /* Public API, accessors
    /**********************************************************
     */

    public BeanProperty getProperty() { return _property; }
    
    public boolean hasValueDeserializer() { return (_valueDeserializer != null); }

    public JavaType getType() { return _type; }

    /*
    /**********************************************************
    /* Public API, deserialization
    /**********************************************************
     */
    
    /**
     * Method called to deserialize appropriate value, given parser (and
     * context), and set it using appropriate method (a setter method).
     */
    public final void deserializeAndSet(JsonParser p, DeserializationContext ctxt,
            Object instance, String propName)
        throws IOException
    {
        try {
            Object key = (_keyDeserializer == null) ? propName
                    : _keyDeserializer.deserializeKey(propName, ctxt);
            set(instance, key, deserialize(p, ctxt));
        } catch (UnresolvedForwardReference reference) {
            if (!(_valueDeserializer.getObjectIdReader() != null)) {
                throw JsonMappingException.from(p, "Unresolved forward reference but no identity info.", reference);
            }
            AnySetterReferring referring = new AnySetterReferring(this, reference,
                    _type.getRawClass(), instance, propName);
            reference.getRoid().appendReferring(referring);
        }
    }

    public Object deserialize(JsonParser p, DeserializationContext ctxt) throws IOException
    {
        if (p.hasToken(JsonToken.VALUE_NULL)) {
            return _valueDeserializer.getNullValue(ctxt);
        }
        if (_valueTypeDeserializer != null) {
            return _valueDeserializer.deserializeWithType(p, ctxt, _valueTypeDeserializer);
        }
        return _valueDeserializer.deserialize(p, ctxt);
    }

    @SuppressWarnings("unchecked")
    public void set(Object instance, Object propName, Object value) throws IOException
    {
        try {
            // if annotation in the field (only map is supported now)
            if (_setterIsField) {
                AnnotatedField field = (AnnotatedField) _setter;
                Map<Object,Object> val = (Map<Object,Object>) field.getValue(instance);
                /* 01-Jun-2016, tatu: At this point it is not quite clear what to do if
                 *    field is `null` -- we cannot necessarily count on zero-args
                 *    constructor except for a small set of types, so for now just
                 *    ignore if null. May need to figure out something better in future.
                 */
                if (val != null) {
                    // add the property key and value
                    val.put(propName, value);
                }
            } else {
                // note: cannot use 'setValue()' due to taking 2 args
                ((AnnotatedMethod) _setter).callOnWith(instance, propName, value);
            }
        } catch (Exception e) {
            _throwAsIOE(e, propName, value);
        }
    }

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

    /**
     * @param e Exception to re-throw or wrap
     * @param propName Name of property (from Json input) to set
     * @param value Value of the property
     */
    protected void _throwAsIOE(Exception e, Object propName, Object value)
        throws IOException
    {
        if (e instanceof IllegalArgumentException) {
            String actType = ClassUtil.classNameOf(value);
            StringBuilder msg = new StringBuilder("Problem deserializing \"any\" property '").append(propName);
            msg.append("' of class "+getClassName()+" (expected type: ").append(_type);
            msg.append("; actual type: ").append(actType).append(")");
            String origMsg = ClassUtil.exceptionMessage(e);
            if (origMsg != null) {
                msg.append(", problem: ").append(origMsg);
            } else {
                msg.append(" (no error message provided)");
            }
            throw new JsonMappingException(null, msg.toString(), e);
        }
        ClassUtil.throwIfIOE(e);
        ClassUtil.throwIfRTE(e);
        // let's wrap the innermost problem
        Throwable t = ClassUtil.getRootCause(e);
        throw new JsonMappingException(null, ClassUtil.exceptionMessage(t), t);
    }

    private String getClassName() { return _setter.getDeclaringClass().getName(); }

    @Override public String toString() { return "[any property on class "+getClassName()+"]"; }

    private static class AnySetterReferring extends Referring {
        private final SettableAnyProperty _parent;
        private final Object _pojo;
        private final String _propName;

        public AnySetterReferring(SettableAnyProperty parent,
                UnresolvedForwardReference reference, Class<?> type, Object instance, String propName)
        {
            super(reference, type);
            _parent = parent;
            _pojo = instance;
            _propName = propName;
        }

        @Override
        public void handleResolvedForwardReference(Object id, Object value)
            throws IOException
        {
            if (!hasId(id)) {
                throw new IllegalArgumentException("Trying to resolve a forward reference with id [" + id.toString()
                        + "] that wasn't previously registered.");
            }
            _parent.set(_pojo, _propName, value);
        }
    }
}

⏎ com/fasterxml/jackson/databind/deser/SettableAnyProperty.java

 

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