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/ser/std/MapProperty.java

package com.fasterxml.jackson.databind.ser.std;

import java.io.IOException;
import java.lang.annotation.Annotation;

import com.fasterxml.jackson.core.JsonGenerator;

import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.introspect.AnnotatedMember;
import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonObjectFormatVisitor;
import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.fasterxml.jackson.databind.ser.PropertyWriter;

/**
 * Helper class needed to support flexible filtering of Map properties
 * with generic JSON Filter functionality. Since {@link java.util.Map}s
 * are not handled as a collection of properties by Jackson (unlike POJOs),
 * bit more wrapping is required.
 */
public class MapProperty extends PropertyWriter
{
    private static final long serialVersionUID = 1L;

    private final static BeanProperty BOGUS_PROP = new BeanProperty.Bogus();
    
    protected final TypeSerializer _typeSerializer;

    protected final BeanProperty _property;

    protected Object _key, _value;

    protected JsonSerializer<Object> _keySerializer, _valueSerializer;

    public MapProperty(TypeSerializer typeSer, BeanProperty prop)
    {
        super((prop == null) ? PropertyMetadata.STD_REQUIRED_OR_OPTIONAL : prop.getMetadata());
        _typeSerializer = typeSer;
        _property = (prop == null) ? BOGUS_PROP : prop;
    }

    /**
     * Initialization method that needs to be called before passing
     * property to filter.
     *
     * @since 2.9
     */
    public void reset(Object key, Object value,
            JsonSerializer<Object> keySer, JsonSerializer<Object> valueSer)
    {
        _key = key;
        _value = value;
        _keySerializer = keySer;
        _valueSerializer = valueSer;
    }

    @Deprecated // since 2.9
    public void reset(Object key,
            JsonSerializer<Object> keySer, JsonSerializer<Object> valueSer)
    {
        reset(key, _value, keySer, valueSer);
    }

    @Override
    public String getName() {
        if (_key instanceof String) {
            return (String) _key;
        }
        return String.valueOf(_key);
    }

    /**
     * @since 2.9
     */
    public Object getValue() {
        return _value;
    }

    /**
     * @since 2.9
     */
    public void setValue(Object v) {
        _value = v;
    }

    @Override
    public PropertyName getFullName() {
        return new PropertyName(getName());
    }

    @Override
    public <A extends Annotation> A getAnnotation(Class<A> acls) {
        return _property.getAnnotation(acls);
    }

    @Override
    public <A extends Annotation> A getContextAnnotation(Class<A> acls) {
        return _property.getContextAnnotation(acls);
    }
    
    @Override
    public void serializeAsField(Object map, JsonGenerator gen,
            SerializerProvider provider) throws IOException
    {
        _keySerializer.serialize(_key, gen, provider);
        if (_typeSerializer == null) {
            _valueSerializer.serialize(_value, gen, provider);
        } else {
            _valueSerializer.serializeWithType(_value, gen, provider, _typeSerializer);
        }
    }

    @Override
    public void serializeAsOmittedField(Object map, JsonGenerator gen,
            SerializerProvider provider) throws Exception
    {
        if (!gen.canOmitFields()) {
            gen.writeOmittedField(getName());
        }
    }

    @Override
    public void serializeAsElement(Object map, JsonGenerator gen,
            SerializerProvider provider) throws Exception
    {
        if (_typeSerializer == null) {
            _valueSerializer.serialize(_value, gen, provider);
        } else {
            _valueSerializer.serializeWithType(_value, gen, provider, _typeSerializer);
        }
    }
    
    @Override
    public void serializeAsPlaceholder(Object value, JsonGenerator gen,
            SerializerProvider provider) throws Exception
    {
        gen.writeNull();
    }

    /*
    /**********************************************************
    /* Rest of BeanProperty, nop
    /**********************************************************
     */
    
    @Override
    public void depositSchemaProperty(JsonObjectFormatVisitor objectVisitor,
            SerializerProvider provider)
        throws JsonMappingException
    {
        _property.depositSchemaProperty(objectVisitor, provider);
    }

    @Override
    @Deprecated
    public void depositSchemaProperty(ObjectNode propertiesNode,
            SerializerProvider provider) throws JsonMappingException {
        // nothing to do here
    }

    @Override
    public JavaType getType() {
        return _property.getType();
    }

    @Override
    public PropertyName getWrapperName() {
        return _property.getWrapperName();
    }

    @Override
    public AnnotatedMember getMember() {
        return _property.getMember();
    }
}

⏎ com/fasterxml/jackson/databind/ser/std/MapProperty.java

 

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