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/deser/std/DateDeserializers.java

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

import java.io.IOException;
import java.lang.reflect.Constructor;
import java.text.*;
import java.util.*;

import com.fasterxml.jackson.annotation.JsonFormat;

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

import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.annotation.JacksonStdImpl;
import com.fasterxml.jackson.databind.cfg.CoercionAction;
import com.fasterxml.jackson.databind.deser.ContextualDeserializer;
import com.fasterxml.jackson.databind.type.LogicalType;
import com.fasterxml.jackson.databind.util.ClassUtil;
import com.fasterxml.jackson.databind.util.StdDateFormat;

/**
 * Container class for core JDK date/time type deserializers.
 */
@SuppressWarnings("serial")
public class DateDeserializers
{
    private final static HashSet<String> _utilClasses = new HashSet<String>();
    static {
        _utilClasses.add("java.util.Calendar");
        _utilClasses.add("java.util.GregorianCalendar");
        _utilClasses.add("java.util.Date");
    }

    public static JsonDeserializer<?> find(Class<?> rawType, String clsName)
    {
        if (_utilClasses.contains(clsName)) {
            // Start with the most common type
            if (rawType == java.util.Calendar.class) {
                return new CalendarDeserializer();
            }
            if (rawType == java.util.Date.class) {
                return DateDeserializer.instance;
            }
            if (rawType == java.util.GregorianCalendar.class) {
                return new CalendarDeserializer(GregorianCalendar.class);
            }
        }
        return null;
    }

    // @since 2.11
    public static boolean hasDeserializerFor(Class<?> rawType) {
        return _utilClasses.contains(rawType.getName());
    }

    /*
    /**********************************************************
    /* Intermediate class for Date-based ones
    /**********************************************************
     */

    protected abstract static class DateBasedDeserializer<T>
        extends StdScalarDeserializer<T>
        implements ContextualDeserializer
    {
        /**
         * Specific format to use, if non-null; if null will
         * just use default format.
         */
        protected final DateFormat _customFormat;

        /**
         * Let's also keep format String for reference, to use for error messages
         */
        protected final String _formatString;

        protected DateBasedDeserializer(Class<?> clz) {
            super(clz);
            _customFormat = null;
            _formatString = null;
        }

        protected DateBasedDeserializer(DateBasedDeserializer<T> base,
                DateFormat format, String formatStr) {
            super(base._valueClass);
            _customFormat = format;
            _formatString = formatStr;
        }

        protected abstract DateBasedDeserializer<T> withDateFormat(DateFormat df, String formatStr);

        @Override // since 2.12
        public LogicalType logicalType() {
            return LogicalType.DateTime;
        }

        @Override
        public JsonDeserializer<?> createContextual(DeserializationContext ctxt,
                BeanProperty property)
           throws JsonMappingException
        {
            final JsonFormat.Value format = findFormatOverrides(ctxt, property,
                    handledType());

            if (format != null) {
                TimeZone tz = format.getTimeZone();
                final Boolean lenient = format.getLenient();

                // First: fully custom pattern?
                if (format.hasPattern()) {
                    final String pattern = format.getPattern();
                    final Locale loc = format.hasLocale() ? format.getLocale() : ctxt.getLocale();
                    SimpleDateFormat df = new SimpleDateFormat(pattern, loc);
                    if (tz == null) {
                        tz = ctxt.getTimeZone();
                    }
                    df.setTimeZone(tz);
                    if (lenient != null) {
                        df.setLenient(lenient);
                    }
                    return withDateFormat(df, pattern);
                }
                // But if not, can still override timezone
                if (tz != null) {
                    DateFormat df = ctxt.getConfig().getDateFormat();
                    // one shortcut: with our custom format, can simplify handling a bit
                    if (df.getClass() == StdDateFormat.class) {
                        final Locale loc = format.hasLocale() ? format.getLocale() : ctxt.getLocale();
                        StdDateFormat std = (StdDateFormat) df;
                        std = std.withTimeZone(tz);
                        std = std.withLocale(loc);
                        if (lenient != null) {
                            std = std.withLenient(lenient);
                        }
                        df = std;
                    } else {
                        // otherwise need to clone, re-set timezone:
                        df = (DateFormat) df.clone();
                        df.setTimeZone(tz);
                        if (lenient != null) {
                            df.setLenient(lenient);
                        }
                    }
                    return withDateFormat(df, _formatString);
                }
                // or maybe even just leniency?
                if (lenient != null) {
                    DateFormat df = ctxt.getConfig().getDateFormat();
                    String pattern = _formatString;
                    // one shortcut: with our custom format, can simplify handling a bit
                    if (df.getClass() == StdDateFormat.class) {
                        StdDateFormat std = (StdDateFormat) df;
                        std = std.withLenient(lenient);
                        df = std;
                        pattern = std.toPattern();
                    } else {
                        // otherwise need to clone,
                        df = (DateFormat) df.clone();
                        df.setLenient(lenient);
                        if (df instanceof SimpleDateFormat) {
                            ((SimpleDateFormat) df).toPattern();
                        }
                    }
                    if (pattern == null) {
                        pattern = "[unknown]";
                    }
                    return withDateFormat(df, pattern);
                }
            }
            return this;
        }

        @Override
        protected java.util.Date _parseDate(JsonParser p, DeserializationContext ctxt)
            throws IOException
        {
            if (_customFormat != null) {
                if (p.hasToken(JsonToken.VALUE_STRING)) {
                    String str = p.getText().trim();
                    if (str.isEmpty()) {
                        final CoercionAction act = _checkFromStringCoercion(ctxt, str);
                        switch (act) { // note: Fail handled above
                        case AsEmpty:
                            return new java.util.Date(0L);
                        case AsNull:
                        case TryConvert:
                        default:
                        }
                        return null;
                    }
                    synchronized (_customFormat) {
                        try {
                            return _customFormat.parse(str);
                        } catch (ParseException e) {
                            return (java.util.Date) ctxt.handleWeirdStringValue(handledType(), str,
                                    "expected format \"%s\"", _formatString);
                        }
                    }
                }
            }
            return super._parseDate(p, ctxt);
        }
    }

    /*
    /**********************************************************
    /* Deserializer implementations for Date types
    /**********************************************************
     */

    @JacksonStdImpl
    public static class CalendarDeserializer extends DateBasedDeserializer<Calendar>
    {
        /**
         * We may know actual expected type; if so, it will be
         * used for instantiation.
         *
         * @since 2.9
         */
        protected final Constructor<Calendar> _defaultCtor;

        public CalendarDeserializer() {
            super(Calendar.class);
            _defaultCtor = null;
        }

        @SuppressWarnings("unchecked")
        public CalendarDeserializer(Class<? extends Calendar> cc) {
            super(cc);
            _defaultCtor = (Constructor<Calendar>) ClassUtil.findConstructor(cc, false);
        }

        public CalendarDeserializer(CalendarDeserializer src, DateFormat df, String formatString) {
            super(src, df, formatString);
            _defaultCtor = src._defaultCtor;
        }

        @Override
        protected CalendarDeserializer withDateFormat(DateFormat df, String formatString) {
            return new CalendarDeserializer(this, df, formatString);
        }

        @Override // since 2.12
        public Object getEmptyValue(DeserializationContext ctxt) {
            GregorianCalendar cal = new GregorianCalendar();
            cal.setTimeInMillis(0L);
            return cal;
        }

        @Override
        public Calendar deserialize(JsonParser p, DeserializationContext ctxt) throws IOException
        {
            Date d = _parseDate(p, ctxt);
            if (d == null) {
                return null;
            }
            if (_defaultCtor == null) {
                return ctxt.constructCalendar(d);
            }
            try {
                Calendar c = _defaultCtor.newInstance();            
                c.setTimeInMillis(d.getTime());
                TimeZone tz = ctxt.getTimeZone();
                if (tz != null) {
                    c.setTimeZone(tz);
                }
                return c;
            } catch (Exception e) {
                return (Calendar) ctxt.handleInstantiationProblem(handledType(), d, e);
            }
        }
    }

    /**
     * Simple deserializer for handling {@link java.util.Date} values.
     *<p>
     * One way to customize Date formats accepted is to override method
     * {@link DeserializationContext#parseDate} that this basic
     * deserializer calls.
     */
    @JacksonStdImpl
    public static class DateDeserializer extends DateBasedDeserializer<Date>
    {
        public final static DateDeserializer instance = new DateDeserializer();

        public DateDeserializer() { super(Date.class); }
        public DateDeserializer(DateDeserializer base, DateFormat df, String formatString) {
            super(base, df, formatString);
        }

        @Override
        protected DateDeserializer withDateFormat(DateFormat df, String formatString) {
            return new DateDeserializer(this, df, formatString);
        }

        @Override // since 2.12
        public Object getEmptyValue(DeserializationContext ctxt) {
            return new Date(0L);
        }
        
        @Override
        public java.util.Date deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
            return _parseDate(p, ctxt);
        }
    }

    /**
     * Compared to plain old {@link java.util.Date}, SQL version is easier
     * to deal with: mostly because it is more limited.
     */
    public static class SqlDateDeserializer
        extends DateBasedDeserializer<java.sql.Date>
    {
        public SqlDateDeserializer() { super(java.sql.Date.class); }
        public SqlDateDeserializer(SqlDateDeserializer src, DateFormat df, String formatString) {
            super(src, df, formatString);
        }

        @Override
        protected SqlDateDeserializer withDateFormat(DateFormat df, String formatString) {
            return new SqlDateDeserializer(this, df, formatString);
        }

        @Override // since 2.12
        public Object getEmptyValue(DeserializationContext ctxt) {
            return new java.sql.Date(0L);
        }

        @Override
        public java.sql.Date deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
            Date d = _parseDate(p, ctxt);
            return (d == null) ? null : new java.sql.Date(d.getTime());
        }
    }

    /**
     * Simple deserializer for handling {@link java.sql.Timestamp} values.
     *<p>
     * One way to customize Timestamp formats accepted is to override method
     * {@link DeserializationContext#parseDate} that this basic
     * deserializer calls.
     */
    public static class TimestampDeserializer extends DateBasedDeserializer<java.sql.Timestamp>
    {
        public TimestampDeserializer() { super(java.sql.Timestamp.class); }
        public TimestampDeserializer(TimestampDeserializer src, DateFormat df, String formatString) {
            super(src, df, formatString);
        }

        @Override
        protected TimestampDeserializer withDateFormat(DateFormat df, String formatString) {
            return new TimestampDeserializer(this, df, formatString);
        }

        @Override // since 2.12
        public Object getEmptyValue(DeserializationContext ctxt) {
            return new java.sql.Timestamp(0L);
        }

        @Override
        public java.sql.Timestamp deserialize(JsonParser p, DeserializationContext ctxt) throws IOException
        {
            Date d = _parseDate(p, ctxt);
            return (d == null) ? null : new java.sql.Timestamp(d.getTime());
        }
    }
}

⏎ com/fasterxml/jackson/databind/deser/std/DateDeserializers.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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