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/DateTimeSerializerBase.java

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

import java.io.IOException;
import java.lang.reflect.Type;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;
import java.util.concurrent.atomic.AtomicReference;

import com.fasterxml.jackson.annotation.JsonFormat;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;

import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.jsonFormatVisitors.*;
import com.fasterxml.jackson.databind.ser.ContextualSerializer;
import com.fasterxml.jackson.databind.util.StdDateFormat;

@SuppressWarnings("serial")
public abstract class DateTimeSerializerBase<T>
    extends StdScalarSerializer<T>
    implements ContextualSerializer
{
    /**
     * Flag that indicates that serialization must be done as the
     * Java timestamp, regardless of other settings.
     */
    protected final Boolean _useTimestamp;

    /**
     * Specific format to use, if not default format: non null value
     * also indicates that serialization is to be done as JSON String,
     * not numeric timestamp, unless {@link #_useTimestamp} is true.
     */
    protected final DateFormat _customFormat;

    /**
     * If {@link #_customFormat} is used, we will try to reuse instances in simplest
     * possible form; thread-safe, but without overhead of <code>ThreadLocal</code>
     * (not from code, but wrt retaining of possibly large number of format instances
     * over all threads, properties with custom formats).
     *
     * @since 2.9
     */
    protected final AtomicReference<DateFormat> _reusedCustomFormat;

    protected DateTimeSerializerBase(Class<T> type,
            Boolean useTimestamp, DateFormat customFormat)
    {
        super(type);
        _useTimestamp = useTimestamp;
        _customFormat = customFormat;
        _reusedCustomFormat = (customFormat == null) ? null : new AtomicReference<DateFormat>();
    }

    public abstract DateTimeSerializerBase<T> withFormat(Boolean timestamp, DateFormat customFormat);

    @Override
    public JsonSerializer<?> createContextual(SerializerProvider serializers,
            BeanProperty property) throws JsonMappingException
    {
        // Note! Should not skip if `property` null since that'd skip check
        // for config overrides, in case of root value
        JsonFormat.Value format = findFormatOverrides(serializers, property, handledType());
        if (format == null) {
            return this;
        }
        // Simple case first: serialize as numeric timestamp?
        JsonFormat.Shape shape = format.getShape();
        if (shape.isNumeric()) {
            return withFormat(Boolean.TRUE, null);
        }

        // 08-Jun-2017, tatu: With [databind#1648], this gets bit tricky..
        // First: custom pattern will override things
        if (format.hasPattern()) {
            final Locale loc = format.hasLocale()
                            ? format.getLocale()
                            : serializers.getLocale();
            SimpleDateFormat df = new SimpleDateFormat(format.getPattern(), loc);
            TimeZone tz = format.hasTimeZone() ? format.getTimeZone()
                    : serializers.getTimeZone();
            df.setTimeZone(tz);
            return withFormat(Boolean.FALSE, df);
        }

        // Otherwise, need one of these changes:
        final boolean hasLocale = format.hasLocale();
        final boolean hasTZ = format.hasTimeZone();
        final boolean asString = (shape == JsonFormat.Shape.STRING);

        if (!hasLocale && !hasTZ && !asString) {
            return this;
        }

        DateFormat df0 = serializers.getConfig().getDateFormat();
        // Jackson's own `StdDateFormat` is quite easy to deal with...
        if (df0 instanceof StdDateFormat) {
            StdDateFormat std = (StdDateFormat) df0;
            if (format.hasLocale()) {
                std = std.withLocale(format.getLocale());
            }
            if (format.hasTimeZone()) {
                std = std.withTimeZone(format.getTimeZone());
            }
            return withFormat(Boolean.FALSE, std);
        }

        // 08-Jun-2017, tatu: Unfortunately there's no generally usable
        //    mechanism for changing `DateFormat` instances (or even clone()ing)
        //    So: require it be `SimpleDateFormat`; can't config other types
        if (!(df0 instanceof SimpleDateFormat)) {
            serializers.reportBadDefinition(handledType(), String.format(
"Configured `DateFormat` (%s) not a `SimpleDateFormat`; cannot configure `Locale` or `TimeZone`",
df0.getClass().getName()));
        }
        SimpleDateFormat df = (SimpleDateFormat) df0;
        if (hasLocale) {
            // Ugh. No way to change `Locale`, create copy; must re-crete completely:
            df = new SimpleDateFormat(df.toPattern(), format.getLocale());
        } else {
            df = (SimpleDateFormat) df.clone();
        }
        TimeZone newTz = format.getTimeZone();
        boolean changeTZ = (newTz != null) && !newTz.equals(df.getTimeZone());
        if (changeTZ) {
            df.setTimeZone(newTz);
        }
        return withFormat(Boolean.FALSE, df);
    }

    /*
    /**********************************************************
    /* Accessors
    /**********************************************************
     */

    @Override
    public boolean isEmpty(SerializerProvider serializers, T value) {
        // 09-Mar-2017, tatu: as per [databind#1550] timestamp 0 is NOT "empty"; but
        //   with versions up to 2.8.x this was the case. Fixed for 2.9.
//        return _timestamp(value) == 0L;
        return false;
    }

    protected abstract long _timestamp(T value);

    @Override
    public JsonNode getSchema(SerializerProvider serializers, Type typeHint) {
        //todo: (ryan) add a format for the date in the schema?
        return createSchemaNode(_asTimestamp(serializers) ? "number" : "string", true);
    }

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

    /*
    /**********************************************************
    /* Actual serialization
    /**********************************************************
     */

    @Override
    public abstract void serialize(T value, JsonGenerator gen, SerializerProvider serializers)
        throws IOException;

    /*
    /**********************************************************
    /* Helper methods
    /**********************************************************
     */
    
    protected boolean _asTimestamp(SerializerProvider serializers)
    {
        if (_useTimestamp != null) {
            return _useTimestamp.booleanValue();
        }
        if (_customFormat == null) {
            if (serializers != null) {
                return serializers.isEnabled(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
            }
            // 12-Jun-2014, tatu: Is it legal not to have provider? Was NPE:ing earlier so leave a check
            throw new IllegalArgumentException("Null SerializerProvider passed for "+handledType().getName());
        }
        return false;
    }

    protected void _acceptJsonFormatVisitor(JsonFormatVisitorWrapper visitor, JavaType typeHint,
		boolean asNumber) throws JsonMappingException
    {
        if (asNumber) {
            visitIntFormat(visitor, typeHint,
                    JsonParser.NumberType.LONG, JsonValueFormat.UTC_MILLISEC);
        } else {
            visitStringFormat(visitor, typeHint, JsonValueFormat.DATE_TIME);
        }
    }

    /**
     * @since 2.9
     */
    protected void _serializeAsString(Date value, JsonGenerator g, SerializerProvider provider) throws IOException
    {
        if (_customFormat == null) {
            provider.defaultSerializeDateValue(value, g);
            return;
        }

        // 19-Jul-2017, tatu: Here we will try a simple but (hopefully) effective mechanism for
        //    reusing formatter instance. This is our second attempt, after initially trying simple
        //    synchronization (which turned out to be bottleneck for some users in production...).
        //    While `ThreadLocal` could alternatively be used, it is likely that it would lead to
        //    higher memory footprint, but without much upside -- if we can not reuse, we'll just
        //    clone(), which has some overhead but not drastic one.
        
        DateFormat f = _reusedCustomFormat.getAndSet(null);
        if (f == null) {
            f = (DateFormat) _customFormat.clone();
        }
        g.writeString(f.format(value));
        _reusedCustomFormat.compareAndSet(null, f);
    }
}

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