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com.fasterxml.jackson.databind.ser.std.StdKeySerializers Maven / Gradle / Ivy
General data-binding functionality for Jackson: works on core streaming API
package com.fasterxml.jackson.databind.ser.std;
import java.io.IOException;
import java.util.Calendar;
import java.util.Date;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.ser.impl.PropertySerializerMap;
import com.fasterxml.jackson.databind.util.EnumValues;
@SuppressWarnings("serial")
public class StdKeySerializers
{
protected final static JsonSerializer DEFAULT_KEY_SERIALIZER = new StdKeySerializer();
protected final static JsonSerializer DEFAULT_STRING_SERIALIZER = new StringKeySerializer();
private StdKeySerializers() { }
/**
* @param config Serialization configuration in use, may be needed in choosing
* serializer to use
* @param rawKeyType Type of key values to serialize
* @param useDefault If no match is found, should we return fallback deserializer
* (true), or null (false)?
*/
public static JsonSerializer getStdKeySerializer(SerializationConfig config,
Class rawKeyType, boolean useDefault)
{
// 24-Sep-2015, tatu: Important -- should ONLY consider types for which `@JsonValue`
// can not be used, since caller has not yet checked for that annotation
// This is why Enum types are not handled here quite yet
// [databind#943: Use a dynamic key serializer if we are not given actual
// type declaration
if ((rawKeyType == null) || (rawKeyType == Object.class)) {
return new Dynamic();
}
if (rawKeyType == String.class) {
return DEFAULT_STRING_SERIALIZER;
}
if (rawKeyType.isPrimitive() || Number.class.isAssignableFrom(rawKeyType)) {
return DEFAULT_KEY_SERIALIZER;
}
if (rawKeyType == Class.class) {
return new Default(Default.TYPE_CLASS, rawKeyType);
}
if (Date.class.isAssignableFrom(rawKeyType)) {
return new Default(Default.TYPE_DATE, rawKeyType);
}
if (Calendar.class.isAssignableFrom(rawKeyType)) {
return new Default(Default.TYPE_CALENDAR, rawKeyType);
}
// other JDK types we know convert properly with 'toString()'?
if (rawKeyType == java.util.UUID.class) {
return new Default(Default.TYPE_TO_STRING, rawKeyType);
}
return useDefault ? DEFAULT_KEY_SERIALIZER : null;
}
/**
* Method called if no specified key serializer was located; will return a
* "default" key serializer.
*
* @since 2.7
*/
@SuppressWarnings("unchecked")
public static JsonSerializer getFallbackKeySerializer(SerializationConfig config,
Class rawKeyType)
{
if (rawKeyType != null) {
// 29-Sep-2015, tatu: Odd case here, of `Enum`, which we may get for `EnumMap`; not sure
// if that is a bug or feature. Regardless, it seems to require dynamic handling
// (compared to getting actual fully typed Enum).
// Note that this might even work from the earlier point, but let's play it safe for now
// 11-Aug-2016, tatu: Turns out we get this if `EnumMap` is the root value because
// then there is no static type
if (rawKeyType == Enum.class) {
return new Dynamic();
}
if (rawKeyType.isEnum()) {
return EnumKeySerializer.construct(rawKeyType,
EnumValues.constructFromName(config, (Class>) rawKeyType));
}
}
return DEFAULT_KEY_SERIALIZER;
}
/**
* @deprecated since 2.7
*/
@Deprecated
public static JsonSerializer getDefault() {
return DEFAULT_KEY_SERIALIZER;
}
/*
/**********************************************************
/* Standard implementations used
/**********************************************************
*/
/**
* This is a "chameleon" style multi-type key serializer for simple
* standard JDK types.
*
* TODO: Should (but does not yet) support re-configuring format used for
* {@link java.util.Date} and {@link java.util.Calendar} key serializers,
* as well as alternative configuration of Enum key serializers.
*/
public static class Default extends StdSerializer {
final static int TYPE_DATE = 1;
final static int TYPE_CALENDAR = 2;
final static int TYPE_CLASS = 3;
final static int TYPE_ENUM = 4;
final static int TYPE_TO_STRING = 5;
protected final int _typeId;
public Default(int typeId, Class type) {
super(type, false);
_typeId = typeId;
}
@Override
public void serialize(Object value, JsonGenerator g, SerializerProvider provider) throws IOException {
switch (_typeId) {
case TYPE_DATE:
provider.defaultSerializeDateKey((Date)value, g);
break;
case TYPE_CALENDAR:
provider.defaultSerializeDateKey(((Calendar) value).getTimeInMillis(), g);
break;
case TYPE_CLASS:
g.writeFieldName(((Class)value).getName());
break;
case TYPE_ENUM:
{
String str = provider.isEnabled(SerializationFeature.WRITE_ENUMS_USING_TO_STRING)
? value.toString() : ((Enum) value).name();
g.writeFieldName(str);
}
break;
case TYPE_TO_STRING:
default:
g.writeFieldName(value.toString());
}
}
}
/**
* Key serializer used when key type is not known statically, and actual key
* serializer needs to be dynamically located.
*/
public static class Dynamic extends StdSerializer
{
// Important: MUST be transient, to allow serialization of key serializer itself
protected transient PropertySerializerMap _dynamicSerializers;
public Dynamic() {
super(String.class, false);
_dynamicSerializers = PropertySerializerMap.emptyForProperties();
}
Object readResolve() {
// Since it's transient, and since JDK serialization by-passes ctor, need this:
_dynamicSerializers = PropertySerializerMap.emptyForProperties();
return this;
}
@Override
public void serialize(Object value, JsonGenerator g, SerializerProvider provider)
throws IOException
{
Class cls = value.getClass();
PropertySerializerMap m = _dynamicSerializers;
JsonSerializer ser = m.serializerFor(cls);
if (ser == null) {
ser = _findAndAddDynamic(m, cls, provider);
}
ser.serialize(value, g, provider);
}
protected JsonSerializer _findAndAddDynamic(PropertySerializerMap map,
Class type, SerializerProvider provider) throws JsonMappingException
{
PropertySerializerMap.SerializerAndMapResult result =
// null -> for now we won't keep ref or pass BeanProperty; could change
map.findAndAddKeySerializer(type, provider, null);
// did we get a new map of serializers? If so, start using it
if (map != result.map) {
_dynamicSerializers = result.map;
}
return result.serializer;
}
}
/**
* Simple and fast key serializer when keys are Strings.
*/
public static class StringKeySerializer extends StdSerializer
{
public StringKeySerializer() { super(String.class, false); }
@Override
public void serialize(Object value, JsonGenerator g, SerializerProvider provider) throws IOException {
g.writeFieldName((String) value);
}
}
/**
* Specialized instance to use for Enum keys, as per [databind#1322]
*
* @since 2.8
*/
public static class EnumKeySerializer extends StdSerializer
{
protected final EnumValues _values;
protected EnumKeySerializer(Class enumType, EnumValues values) {
super(enumType, false);
_values = values;
}
public static EnumKeySerializer construct(Class enumType,
EnumValues enumValues)
{
return new EnumKeySerializer(enumType, enumValues);
}
@Override
public void serialize(Object value, JsonGenerator g, SerializerProvider serializers)
throws IOException
{
if (serializers.isEnabled(SerializationFeature.WRITE_ENUMS_USING_TO_STRING)) {
g.writeFieldName(value.toString());
return;
}
Enum en = (Enum) value;
g.writeFieldName(_values.serializedValueFor(en));
}
}
}
