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/ser/std/BooleanSerializer.java

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

import java.io.IOException;
import java.lang.reflect.Type;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser.NumberType;
import com.fasterxml.jackson.databind.BeanProperty;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.annotation.JacksonStdImpl;
import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonFormatVisitorWrapper;
import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
import com.fasterxml.jackson.databind.ser.ContextualSerializer;

/**
 * Serializer used for primitive boolean, as well as java.util.Boolean
 * wrapper type.
 *<p>
 * Since this is one of "natural" (aka "native") types, no type information is ever
 * included on serialization (unlike for most other scalar types)
 */
@JacksonStdImpl
public final class BooleanSerializer
//In 2.9, removed use of intermediate type `NonTypedScalarSerializerBase`
    extends StdScalarSerializer<Object>
    implements ContextualSerializer
{
    private static final long serialVersionUID = 1L;

    /**
     * Whether type serialized is primitive (boolean) or wrapper
     * (java.lang.Boolean); if true, former, if false, latter.
     */
    protected final boolean _forPrimitive;

    public BooleanSerializer(boolean forPrimitive) {
        super(forPrimitive ? Boolean.TYPE : Boolean.class, false);
        _forPrimitive = forPrimitive;
    }

    @Override
    public JsonSerializer<?> createContextual(SerializerProvider serializers,
            BeanProperty property) throws JsonMappingException
    {
        // 16-Mar-2021, tatu: As per [databind#3080], was passing wrapper type
        //    always; should not have.
        JsonFormat.Value format = findFormatOverrides(serializers, property,
                handledType());
        if (format != null) {
            JsonFormat.Shape shape = format.getShape();
            if (shape.isNumeric()) {
                return new AsNumber(_forPrimitive);
            }
            if (shape == JsonFormat.Shape.STRING) {
                return new ToStringSerializer(_handledType);
            }
        }
        return this;
    }

    @Override
    public void serialize(Object value, JsonGenerator g, SerializerProvider provider) throws IOException {
        g.writeBoolean(Boolean.TRUE.equals(value));
    }

    @Override
    public final void serializeWithType(Object value, JsonGenerator g, SerializerProvider provider,
            TypeSerializer typeSer) throws IOException
    {
        g.writeBoolean(Boolean.TRUE.equals(value));
    }

    @Override
    public JsonNode getSchema(SerializerProvider provider, Type typeHint) {
        return createSchemaNode("boolean", !_forPrimitive);
    }

    @Override
    public void acceptJsonFormatVisitor(JsonFormatVisitorWrapper visitor, JavaType typeHint) throws JsonMappingException {
        visitor.expectBooleanFormat(typeHint);
    }

    /**
     * Alternate implementation that is used when values are to be serialized
     * as numbers <code>0</code> (false) or <code>1</code> (true).
     * 
     * @since 2.9
     */
    final static class AsNumber
        extends StdScalarSerializer<Object>
        implements ContextualSerializer
    {
        private static final long serialVersionUID = 1L;

        /**
         * Whether type serialized is primitive (boolean) or wrapper
         * (java.lang.Boolean); if true, former, if false, latter.
         */
        protected final boolean _forPrimitive;

        public AsNumber(boolean forPrimitive) {
            super(forPrimitive ? Boolean.TYPE : Boolean.class, false);
            _forPrimitive = forPrimitive;
        }

        @Override
        public void serialize(Object value, JsonGenerator g, SerializerProvider provider) throws IOException {
            g.writeNumber((Boolean.FALSE.equals(value)) ? 0 : 1);
        }

        @Override
        public final void serializeWithType(Object value, JsonGenerator g, SerializerProvider provider,
                TypeSerializer typeSer) throws IOException
        {
            // 27-Mar-2017, tatu: Actually here we CAN NOT serialize as number without type,
            //    since with natural types that would map to number, not boolean. So choice
            //    comes to between either add type id, or serialize as boolean. Choose
            //    latter at this point
            g.writeBoolean(Boolean.TRUE.equals(value));
        }

        @Override
        public void acceptJsonFormatVisitor(JsonFormatVisitorWrapper visitor, JavaType typeHint) throws JsonMappingException {
            // 27-Mar-2017, tatu: As usual, bit tricky but... seems like we should call
            //    visitor for actual representation
            visitIntFormat(visitor, typeHint, NumberType.INT);
        }

        @Override
        public JsonSerializer<?> createContextual(SerializerProvider serializers,
                BeanProperty property) throws JsonMappingException
        {
            JsonFormat.Value format = findFormatOverrides(serializers,
                    property, Boolean.class);
            if (format != null) {
                JsonFormat.Shape shape = format.getShape();
                if (!shape.isNumeric()) {
                    return new BooleanSerializer(_forPrimitive);
                }
            }
            return this;
        }
    }
}

⏎ com/fasterxml/jackson/databind/ser/std/BooleanSerializer.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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