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/StaticListSerializerBase.java

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

import java.io.IOException;
import java.lang.reflect.Type;
import java.util.*;
import java.util.Objects;

import com.fasterxml.jackson.annotation.JsonFormat;

import com.fasterxml.jackson.core.JsonGenerator;

import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.introspect.AnnotatedMember;
import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonArrayFormatVisitor;
import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonFormatVisitorWrapper;
import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
import com.fasterxml.jackson.databind.ser.ContextualSerializer;

/**
 * Intermediate base class for Lists, Collections and Arrays
 * that contain static (non-dynamic) value types.
 */
@SuppressWarnings("serial")
public abstract class StaticListSerializerBase<T extends Collection<?>>
    extends StdSerializer<T>
    implements ContextualSerializer
{
    /**
     * Setting for specific local override for "unwrap single element arrays":
     * true for enable unwrapping, false for preventing it, `null` for using
     * global configuration.
     *
     * @since 2.6
     */
    protected final Boolean _unwrapSingle;

    protected StaticListSerializerBase(Class<?> cls) {
        super(cls, false);
        _unwrapSingle = null;
    }

    /**
     * @since 2.9
     */
    protected StaticListSerializerBase(StaticListSerializerBase<?> src,
            Boolean unwrapSingle) {
        super(src);
        _unwrapSingle = unwrapSingle;
    }

    /**
     * @since 2.9
     */
    public abstract JsonSerializer<?> _withResolved(BeanProperty prop,
            Boolean unwrapSingle);

    /*
    /**********************************************************
    /* Post-processing
    /**********************************************************
     */

    @SuppressWarnings("unchecked")
    @Override
    public JsonSerializer<?> createContextual(SerializerProvider serializers,
            BeanProperty property)
        throws JsonMappingException
    {
        JsonSerializer<?> ser = null;
        Boolean unwrapSingle = null;
        
        if (property != null) {
            final AnnotationIntrospector intr = serializers.getAnnotationIntrospector();
            AnnotatedMember m = property.getMember();
            if (m != null) {
                Object serDef = intr.findContentSerializer(m);
                if (serDef != null) {
                    ser = serializers.serializerInstance(m, serDef);
                }
            }
        }
        JsonFormat.Value format = findFormatOverrides(serializers, property, handledType());
        if (format != null) {
            unwrapSingle = format.getFeature(JsonFormat.Feature.WRITE_SINGLE_ELEM_ARRAYS_UNWRAPPED);
        }
        // [databind#124]: May have a content converter
        ser = findContextualConvertingSerializer(serializers, property, ser);
        if (ser == null) {
            ser = serializers.findContentValueSerializer(String.class, property);
        }
        // Optimization: default serializer just writes String, so we can avoid a call:
        if (isDefaultSerializer(ser)) {
            if (Objects.equals(unwrapSingle, _unwrapSingle)) {
                return this;
            }
            return _withResolved(property, unwrapSingle);
        }
        // otherwise...
        // note: will never have TypeSerializer, because Strings are "natural" type
        return new CollectionSerializer(serializers.constructType(String.class),
                true, /*TypeSerializer*/ null, (JsonSerializer<Object>) ser);
    }

    @Override
    public boolean isEmpty(SerializerProvider provider, T value) {
        return (value == null) || (value.size() == 0);
    }

    @Override
    public JsonNode getSchema(SerializerProvider provider, Type typeHint) {
        return createSchemaNode("array", true).set("items", contentSchema());
    }

    @Override
    public void acceptJsonFormatVisitor(JsonFormatVisitorWrapper visitor, JavaType typeHint) throws JsonMappingException {
        JsonArrayFormatVisitor v2 = visitor.expectArrayFormat(typeHint);
        if (v2 != null) {
            acceptContentVisitor(v2);
        }
    }

    /*
    /**********************************************************
    /* Abstract methods for sub-classes to implement
    /**********************************************************
     */

    protected abstract JsonNode contentSchema();

    protected abstract void acceptContentVisitor(JsonArrayFormatVisitor visitor)
        throws JsonMappingException;

    // just to make sure it gets implemented:
    @Override
    public abstract void serializeWithType(T value, JsonGenerator g,
            SerializerProvider provider, TypeSerializer typeSer) throws IOException;
}

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

 

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