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/NumberSerializers.java

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

import java.io.IOException;
import java.lang.reflect.Type;
import java.math.BigDecimal;
import java.util.Map;

import com.fasterxml.jackson.annotation.JsonFormat;

import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.core.io.NumberOutput;
import com.fasterxml.jackson.core.type.WritableTypeId;
import com.fasterxml.jackson.databind.*;
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;

/**
 * Container class for serializers used for handling standard JDK-provided
 * primitve number types and their wrapper counterparts (like {@link java.lang.Integer}).
 */
@SuppressWarnings("serial")
public class NumberSerializers {
    protected NumberSerializers() { }

    public static void addAll(Map<String, JsonSerializer<?>> allDeserializers) {
        allDeserializers.put(Integer.class.getName(), new IntegerSerializer(Integer.class));
        allDeserializers.put(Integer.TYPE.getName(), new IntegerSerializer(Integer.TYPE));
        allDeserializers.put(Long.class.getName(), new LongSerializer(Long.class));
        allDeserializers.put(Long.TYPE.getName(), new LongSerializer(Long.TYPE));

        allDeserializers.put(Byte.class.getName(), IntLikeSerializer.instance);
        allDeserializers.put(Byte.TYPE.getName(), IntLikeSerializer.instance);
        allDeserializers.put(Short.class.getName(), ShortSerializer.instance);
        allDeserializers.put(Short.TYPE.getName(), ShortSerializer.instance);

        // Numbers, limited length floating point
        allDeserializers.put(Double.class.getName(), new DoubleSerializer(Double.class));
        allDeserializers.put(Double.TYPE.getName(), new DoubleSerializer(Double.TYPE));
        allDeserializers.put(Float.class.getName(), FloatSerializer.instance);
        allDeserializers.put(Float.TYPE.getName(), FloatSerializer.instance);
    }

    /*
    /**********************************************************
    /* Shared base class
    /**********************************************************
     */

    /**
     * Shared base class for actual primitive/wrapper number serializers.
     * Note that this class is not meant as general-purpose base class nor
     * is it part of public API: you may extend it with the caveat that not
     * being part of public API its implementation and interfaces may change
     * in minor releases; however deprecation markers will be used to allow
     * code evolution.
     *<p>
     * NOTE: {@code public} since 2.10: previously had {@code protected} access.
     */
    public abstract static class Base<T> extends StdScalarSerializer<T>
            implements ContextualSerializer
    {
        protected final JsonParser.NumberType _numberType;
        protected final String _schemaType;
        protected final boolean _isInt;

        protected Base(Class<?> cls, JsonParser.NumberType numberType,
                String schemaType) {
            super(cls, false);
            _numberType = numberType;
            _schemaType = schemaType;
            _isInt = (numberType == JsonParser.NumberType.INT)
                    || (numberType == JsonParser.NumberType.LONG)
                    || (numberType == JsonParser.NumberType.BIG_INTEGER);
        }

        @Override
        public JsonNode getSchema(SerializerProvider provider, Type typeHint) {
            return createSchemaNode(_schemaType, true);
        }

        @Override
        public void acceptJsonFormatVisitor(JsonFormatVisitorWrapper visitor,
                JavaType typeHint) throws JsonMappingException
        {
            if (_isInt) {
                visitIntFormat(visitor, typeHint, _numberType);
            } else {
                visitFloatFormat(visitor, typeHint, _numberType);
            }
        }

        @Override
        public JsonSerializer<?> createContextual(SerializerProvider prov,
                BeanProperty property) throws JsonMappingException
        {
            JsonFormat.Value format = findFormatOverrides(prov, property, handledType());
            if (format != null) {
                switch (format.getShape()) {
                case STRING:
                    if (((Class<?>) handledType()) == BigDecimal.class) {
                        return NumberSerializer.bigDecimalAsStringSerializer();
                    }
                    return ToStringSerializer.instance;
                default:
                }
            }
            return this;
        }
    }

    /*
     *************************************************************
     * Concrete serializers, numerics
     *************************************************************
     */

    @JacksonStdImpl
    public static class ShortSerializer extends Base<Object> {
        final static ShortSerializer instance = new ShortSerializer();

        public ShortSerializer() {
            super(Short.class, JsonParser.NumberType.INT, "number");
        }

        @Override
        public void serialize(Object value, JsonGenerator gen,
                SerializerProvider provider) throws IOException {
            gen.writeNumber(((Short) value).shortValue());
        }
    }

    /**
     * This is the special serializer for regular {@link java.lang.Integer}s
     * (and primitive ints)
     * <p>
     * Since this is one of "natural" types, no type information is ever included
     * on serialization (unlike for most scalar types, except for {@code double}).
     * <p>
     * NOTE: as of 2.6, generic signature changed to Object, to avoid generation
     * of bridge methods.
     */
    @JacksonStdImpl
    public static class IntegerSerializer extends Base<Object> {
        public IntegerSerializer(Class<?> type) {
            super(type, JsonParser.NumberType.INT, "integer");
        }

        @Override
        public void serialize(Object value, JsonGenerator gen,
                SerializerProvider provider) throws IOException {
            gen.writeNumber(((Integer) value).intValue());
        }

        // IMPORTANT: copied from `NonTypedScalarSerializerBase`
        @Override
        public void serializeWithType(Object value, JsonGenerator gen,
                SerializerProvider provider, TypeSerializer typeSer)
                throws IOException {
            // no type info, just regular serialization
            serialize(value, gen, provider);
        }
    }

    /**
     * Similar to {@link IntegerSerializer}, but will not cast to Integer:
     * instead, cast is to {@link java.lang.Number}, and conversion is by
     * calling {@link java.lang.Number#intValue}.
     */
    @JacksonStdImpl
    public static class IntLikeSerializer extends Base<Object> {
        final static IntLikeSerializer instance = new IntLikeSerializer();

        public IntLikeSerializer() {
            super(Number.class, JsonParser.NumberType.INT, "integer");
        }

        @Override
        public void serialize(Object value, JsonGenerator gen,
                SerializerProvider provider) throws IOException {
            gen.writeNumber(((Number) value).intValue());
        }
    }

    @JacksonStdImpl
    public static class LongSerializer extends Base<Object> {
        public LongSerializer(Class<?> cls) {
            super(cls, JsonParser.NumberType.LONG, "number");
        }

        @Override
        public void serialize(Object value, JsonGenerator gen,
                SerializerProvider provider) throws IOException {
            gen.writeNumber(((Long) value).longValue());
        }
    }

    @JacksonStdImpl
    public static class FloatSerializer extends Base<Object> {
        final static FloatSerializer instance = new FloatSerializer();

        public FloatSerializer() {
            super(Float.class, JsonParser.NumberType.FLOAT, "number");
        }

        @Override
        public void serialize(Object value, JsonGenerator gen,
                SerializerProvider provider) throws IOException {
            gen.writeNumber(((Float) value).floatValue());
        }
    }

    /**
     * This is the special serializer for regular {@link java.lang.Double}s (and
     * primitive doubles)
     * <p>
     * Since this is one of "native" types, no type information is ever included
     * on serialization (unlike for most scalar types other than {@code long}).
     */
    @JacksonStdImpl
    public static class DoubleSerializer extends Base<Object> {
        public DoubleSerializer(Class<?> cls) {
            super(cls, JsonParser.NumberType.DOUBLE, "number");
        }

        @Override
        public void serialize(Object value, JsonGenerator gen,
                SerializerProvider provider) throws IOException
        {
            gen.writeNumber(((Double) value).doubleValue());
        }

        // IMPORTANT: copied from `NonTypedScalarSerializerBase`
        @Override
        public void serializeWithType(Object value, JsonGenerator g,
                SerializerProvider provider, TypeSerializer typeSer)
            throws IOException
        {
            // 08-Feb-2018, tatu: [databind#2236], NaN values need special care
            Double d = (Double) value;
            if (NumberOutput.notFinite(d)) {
                WritableTypeId typeIdDef = typeSer.writeTypePrefix(g,
                        // whether to indicate it's number or string is arbitrary; important it is scalar
                        typeSer.typeId(value, JsonToken.VALUE_NUMBER_FLOAT));
                g.writeNumber(d);
                typeSer.writeTypeSuffix(g, typeIdDef);
            } else {
                g.writeNumber(d);
            }
        }

        @Deprecated // since 2.13, call NumberOutput.notFinite() directly
        public static boolean notFinite(double value) {
            return NumberOutput.notFinite(value);
        }
    }
}

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