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/jsontype/TypeSerializer.java

package com.fasterxml.jackson.databind.jsontype;

import java.io.IOException;

import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.core.type.WritableTypeId;
import com.fasterxml.jackson.core.util.VersionUtil;
import com.fasterxml.jackson.databind.BeanProperty;
import com.fasterxml.jackson.annotation.JsonTypeInfo;

/**
 * Interface for serializing type information regarding instances of specified
 * base type (super class), so that exact subtype can be properly deserialized
 * later on. These instances are to be called by regular
 * {@link com.fasterxml.jackson.databind.JsonSerializer}s using proper contextual
 * calls, to add type information using mechanism type serializer was
 * configured with.
 *<p>
 * NOTE: version 2.9 contains significant attempt at simplifying interface,
 * as well as giving format implementation (via {@link JsonGenerator}) more
 * control over actual serialization details. Minor changes are required to change
 * call pattern so that return value of "prefix" write needs to be passed to "suffix"
 * write.
 */
public abstract class TypeSerializer
{
    /*
    /**********************************************************
    /* Initialization
    /**********************************************************
     */

    /**
     * Method called to create contextual version, to be used for
     * values of given property. This may be the type itself
     * (as is the case for bean properties), or values contained
     * (for {@link java.util.Collection} or {@link java.util.Map}
     * valued properties).
     * 
     * @since 2.0
     */
    public abstract TypeSerializer forProperty(BeanProperty prop);

    /*
    /**********************************************************
    /* Introspection
    /**********************************************************
     */

    /**
     * Accessor for type information inclusion method
     * that serializer uses; indicates how type information
     * is embedded in resulting JSON.
     */
    public abstract JsonTypeInfo.As getTypeInclusion();

    /**
     * Name of property that contains type information, if
     * property-based inclusion is used.
     */
    public abstract String getPropertyName();

    /**
     * Accessor for object that handles conversions between
     * types and matching type ids.
     */
    public abstract TypeIdResolver getTypeIdResolver();

    /*
    /**********************************************************
    /* Type serialization methods: new (2.9)
    /**********************************************************
     */

    /**
     * Factory method for constructing type id value object to pass to
     * {@link #writeTypePrefix}.
     */
    public WritableTypeId typeId(Object value, JsonToken valueShape) {
        WritableTypeId typeIdDef = new WritableTypeId(value, valueShape);
        switch (getTypeInclusion()) {
        case EXISTING_PROPERTY:
            typeIdDef.include = WritableTypeId.Inclusion.PAYLOAD_PROPERTY;
            typeIdDef.asProperty = getPropertyName();
            break;
        case EXTERNAL_PROPERTY:
            typeIdDef.include = WritableTypeId.Inclusion.PARENT_PROPERTY;
            typeIdDef.asProperty = getPropertyName();
            break;
        case PROPERTY:
            typeIdDef.include = WritableTypeId.Inclusion.METADATA_PROPERTY;
            typeIdDef.asProperty = getPropertyName();
            break;
        case WRAPPER_ARRAY:
            typeIdDef.include = WritableTypeId.Inclusion.WRAPPER_ARRAY;
            break;
        case WRAPPER_OBJECT:
            typeIdDef.include = WritableTypeId.Inclusion.WRAPPER_OBJECT;
            break;
        default:
            VersionUtil.throwInternal();
        }
        return typeIdDef;
    }

    public WritableTypeId typeId(Object value, JsonToken valueShape,
            Object id) {
        WritableTypeId typeId = typeId(value, valueShape);
        typeId.id = id;
        return typeId;
    }

    public WritableTypeId typeId(Object value, Class<?> typeForId,
            JsonToken valueShape) {
        WritableTypeId typeId = typeId(value, valueShape);
        typeId.forValueType = typeForId;
        return typeId;
    }

    /**
     * Method called to write initial part of type information for given
     * value, along with possible wrapping to use: details are specified
     * by `typeId` argument.
     * Note that for structured types (Object, Array), this call will add
     * necessary start token so it should NOT be explicitly written, unlike
     * with non-type-id value writes.
     *<p>
     * See {@link #writeTypeSuffix(JsonGenerator, WritableTypeId)} for a complete
     * example of typical usage.
     *
     * @param g Generator to use for outputting type id and possible wrapping
     * @param typeId Details of what type id is to be written, how.
     * 
     * @since 2.9
     */
    public abstract WritableTypeId writeTypePrefix(JsonGenerator g,
            WritableTypeId typeId) throws IOException;

    /**
     * Method that should be called after {@link #writeTypePrefix(JsonGenerator, WritableTypeId)}
     * and matching value write have been called, passing {@link WritableTypeId} returned.
     * Usual idiom is:
     *<pre>
     * // Indicator generator that type identifier may be needed; generator may write
     * // one as suggested, modify information, or take some other action 
     * // NOTE! For Object/Array types, this will ALSO write start marker!
     * WritableTypeId typeIdDef = typeSer.writeTypePrefix(gen,
     *          typeSer.typeId(value, JsonToken.START_OBJECT));
     *
     * // serializing actual value for which TypeId may have been written... like
     * // NOTE: do NOT write START_OBJECT before OR END_OBJECT after:
     * g.writeStringField("message", "Hello, world!"
     *
     * // matching type suffix call to let generator chance to add suffix, if any
     * // NOTE! For Object/Array types, this will ALSO write end marker!
     * typeSer.writeTypeSuffix(gen, typeIdDef);
     *</pre>
     *
     * @since 2.9
     */
    public abstract WritableTypeId writeTypeSuffix(JsonGenerator g,
            WritableTypeId typeId) throws IOException;

    /*
    /**********************************************************
    /* Legacy type serialization methods
    /**********************************************************
     */

    /**
     * DEPRECATED: now equivalent to:
     *{@code writeTypePrefix(g, typeId(value, JsonToken.VALUE_STRING));}.
     * See {@link #writeTypePrefix} for more info.
     *
     * @deprecated Since 2.9 use {@link #writeTypePrefix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeTypePrefixForScalar(Object value, JsonGenerator g) throws IOException {
        writeTypePrefix(g, typeId(value, JsonToken.VALUE_STRING));
    }

    /**
     * DEPRECATED: now equivalent to:
     *{@code writeTypePrefix(g, typeId(value, JsonToken.START_OBJECT));}.
     * See {@link #writeTypePrefix} for more info.
     *
     * @deprecated Since 2.9 use {@link #writeTypePrefix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeTypePrefixForObject(Object value, JsonGenerator g) throws IOException {
        writeTypePrefix(g, typeId(value, JsonToken.START_OBJECT));
    }

    /**
     * DEPRECATED: now equivalent to:
     *{@code writeTypePrefix(g, typeId(value, JsonToken.START_ARRAY));}.
     * See {@link #writeTypePrefix} for more info.
     *
     * @deprecated Since 2.9 use {@link #writeTypePrefix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeTypePrefixForArray(Object value, JsonGenerator g) throws IOException {
        writeTypePrefix(g, typeId(value, JsonToken.START_ARRAY));
    }

    /**
     * DEPRECATED: now equivalent to:
     *{@code writeTypeSuffix(g, typeId(value, JsonToken.VALUE_STRING));}.
     * See {@link #writeTypeSuffix} for more info.
     *
     * @deprecated Since 2.9 use {@link #writeTypeSuffix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeTypeSuffixForScalar(Object value, JsonGenerator g) throws IOException {
        _writeLegacySuffix(g, typeId(value, JsonToken.VALUE_STRING));
    }

    /**
     * DEPRECATED: now equivalent to:
     *{@code writeTypeSuffix(g, typeId(value, JsonToken.START_OBJECT));}.
     * See {@link #writeTypeSuffix} for more info.
     *
     * @deprecated Since 2.9 use {@link #writeTypeSuffix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeTypeSuffixForObject(Object value, JsonGenerator g) throws IOException {
        _writeLegacySuffix(g, typeId(value, JsonToken.START_OBJECT));
    }

    /**
     * DEPRECATED: now equivalent to:
     *{@code writeTypeSuffix(g, typeId(value, JsonToken.START_ARRAY));}.
     * See {@link #writeTypeSuffix} for more info.
     *
     * @deprecated Since 2.9 use {@link #writeTypeSuffix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeTypeSuffixForArray(Object value, JsonGenerator g) throws IOException {
        _writeLegacySuffix(g, typeId(value, JsonToken.START_ARRAY));
    }

    /**
     * DEPRECATED: now equivalent to:
     *{@code writeTypePrefix(g, typeId(value, type, JsonToken.VALUE_STRING));}.
     * See {@link #writeTypePrefix} for more info.
     *
     * @deprecated Since 2.9 use {@link #writeTypePrefix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeTypePrefixForScalar(Object value, JsonGenerator g, Class<?> type) throws IOException {
        writeTypePrefix(g, typeId(value, type, JsonToken.VALUE_STRING));
    }

    /**
     * DEPRECATED: now equivalent to:
     *{@code writeTypePrefix(g, typeId(value, type, JsonToken.START_OBJECT));}.
     * See {@link #writeTypePrefix} for more info.
     *
     * @deprecated Since 2.9 use {@link #writeTypePrefix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeTypePrefixForObject(Object value, JsonGenerator g, Class<?> type) throws IOException {
        writeTypePrefix(g, typeId(value, type, JsonToken.START_OBJECT));
    }

    /**
     * DEPRECATED: now equivalent to:
     *{@code writeTypePrefix(g, typeId(value, type, JsonToken.START_ARRAY));}.
     * See {@link #writeTypePrefix} for more info.
     *
     * @deprecated Since 2.9 use {@link #writeTypePrefix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeTypePrefixForArray(Object value, JsonGenerator g, Class<?> type) throws IOException {
        writeTypePrefix(g, typeId(value, type, JsonToken.START_ARRAY));
    }

    /*
    /**********************************************************
    /* Type serialization methods with type id override
    /**********************************************************
     */

    /**
     * DEPRECATED: now equivalent to:
     *{@code writeTypePrefix(g, typeId(value, JsonToken.VALUE_STRING, typeId));}.
     * See {@link #writeTypePrefix} for more info.
     *
     * @deprecated Since 2.9 use {@link #writeTypePrefix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeCustomTypePrefixForScalar(Object value, JsonGenerator g, String typeId) throws IOException {
        writeTypePrefix(g, typeId(value, JsonToken.VALUE_STRING, typeId));
    }

    /**
     * DEPRECATED: now equivalent to:
     *{@code writeTypePrefix(g, typeId(value, JsonToken.START_OBJECT, typeId));}.
     * See {@link #writeTypePrefix} for more info.
     *
     * @deprecated Since 2.9 use {@link #writeTypePrefix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeCustomTypePrefixForObject(Object value, JsonGenerator g, String typeId) throws IOException {
        writeTypePrefix(g, typeId(value, JsonToken.START_OBJECT, typeId));
    }

    /**
     * DEPRECATED: now equivalent to:
     *{@code writeTypePrefix(g, typeId(value, JsonToken.START_ARRAY, typeId));}.
     * See {@link #writeTypePrefix} for more info.
     *
     * @deprecated Since 2.9 use {@link #writeTypePrefix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeCustomTypePrefixForArray(Object value, JsonGenerator g, String typeId) throws IOException {
        writeTypePrefix(g, typeId(value, JsonToken.START_ARRAY, typeId));
    }

    /**
     * @deprecated Since 2.9 use {@link #writeTypeSuffix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeCustomTypeSuffixForScalar(Object value, JsonGenerator g, String typeId) throws IOException {
        _writeLegacySuffix(g, typeId(value, JsonToken.VALUE_STRING, typeId));
    }

    /**
     * @deprecated Since 2.9 use {@link #writeTypeSuffix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeCustomTypeSuffixForObject(Object value, JsonGenerator g, String typeId) throws IOException {
        _writeLegacySuffix(g, typeId(value, JsonToken.START_OBJECT, typeId));
    }

    /**
     * @deprecated Since 2.9 use {@link #writeTypeSuffix(JsonGenerator, WritableTypeId)} instead
     */
    @Deprecated // since 2.9
    public void writeCustomTypeSuffixForArray(Object value, JsonGenerator g, String typeId) throws IOException {
        _writeLegacySuffix(g, typeId(value, JsonToken.START_ARRAY, typeId));
    }

    /**
     * Helper method needed for backwards compatibility: since original type id
     * can not be routed through completely, we have to reverse-engineer likely
     * setting before calling suffix.
     *
     * @since 2.9
     */
    protected final void _writeLegacySuffix(JsonGenerator g,
            WritableTypeId typeId) throws IOException
    {
        // most likely logic within generator is this:
        typeId.wrapperWritten = !g.canWriteTypeId();
        writeTypeSuffix(g, typeId);
    }
}

⏎ com/fasterxml/jackson/databind/jsontype/TypeSerializer.java

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File name: jackson-databind-2.14.0-sources.jar
File size: 1187952 bytes
Release date: 2022-11-05
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