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General data-binding functionality for Jackson: works on core streaming API
package com.fasterxml.jackson.databind.deser.std;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.util.List;
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.deser.KeyDeserializers;
import com.fasterxml.jackson.databind.introspect.AnnotatedAndMetadata;
import com.fasterxml.jackson.databind.introspect.AnnotatedConstructor;
import com.fasterxml.jackson.databind.introspect.AnnotatedMember;
import com.fasterxml.jackson.databind.introspect.AnnotatedMethod;
import com.fasterxml.jackson.databind.util.ClassUtil;
import com.fasterxml.jackson.databind.util.EnumResolver;
/**
* Helper class used to contain simple/well-known key deserializers.
* Following kinds of Objects can be handled currently:
*
* - Primitive wrappers (Boolean, Byte, Char, Short, Integer, Float, Long, Double)
* - Enums (usually not needed, since EnumMap doesn't call us)
* - {@link java.util.Date}
* - {@link java.util.Calendar}
* - {@link java.util.UUID}
* - {@link java.util.Locale}
* - Anything with constructor that takes a single String arg
* (if not explicitly @JsonIgnore'd)
* - Anything with {@code static T valueOf(String)} factory method
* (if not explicitly @JsonIgnore'd)
*
*/
public class StdKeyDeserializers
implements KeyDeserializers, java.io.Serializable
{
private static final long serialVersionUID = 1L;
public static KeyDeserializer constructEnumKeyDeserializer(EnumResolver enumResolver) {
return new StdKeyDeserializer.EnumKD(enumResolver, null);
}
public static KeyDeserializer constructEnumKeyDeserializer(EnumResolver enumResolver,
AnnotatedMethod factory) {
return new StdKeyDeserializer.EnumKD(enumResolver, factory);
}
public static KeyDeserializer constructDelegatingKeyDeserializer(DeserializationConfig config,
JavaType type, JsonDeserializer deser)
{
return new StdKeyDeserializer.DelegatingKD(type.getRawClass(), deser);
}
public static KeyDeserializer findStringBasedKeyDeserializer(DeserializationConfig config,
JavaType type)
throws JsonMappingException
{
// 15-Jun-2021, tatu: As per [databind#3143], full introspection needs to consider
// as set of possibilities. Basically, precedence is:
//
// 1. Explicitly annotated 1-String-arg constructor, if one exists
// 2. Explicitly annotated Factory method: just one allowed (exception if multiple)
// 3. Implicit 1-String-arg constructor (no visibility checks for backwards
// compatibility reasons; should probably be checked in future, 3.0?)
// 4. Implicit Factory method with name of "valueOf()" (primary) or
// "fromString()" (secondary). Likewise, no visibility check as of yet.
// We don't need full deserialization information, just need to know creators.
final BeanDescription beanDesc = config.introspectForCreation(type);
// Ok, so: can we find T(String) constructor?
final AnnotatedAndMetadata ctorInfo = _findStringConstructor(beanDesc);
// Explicit?
if ((ctorInfo != null) && (ctorInfo.metadata != null)) {
return _constructCreatorKeyDeserializer(config, ctorInfo.annotated);
}
// or if not, "static T valueOf(String)" (or equivalent marked
// with @JsonCreator annotation?)
final List> factoryCandidates
= beanDesc.getFactoryMethodsWithMode();
// But must now filter out invalid candidates, both by signature (must take 1 and
// only 1 arg; that arg must be of type `String`) and by annotations (we only
// accept "delegating" style, so remove PROPERTIES)
factoryCandidates.removeIf(m ->
(m.annotated.getParameterCount() != 1)
|| (m.annotated.getRawParameterType(0) != String.class)
|| (m.metadata == JsonCreator.Mode.PROPERTIES)
);
// Any explicit?
final AnnotatedMethod explicitFactory = _findExplicitStringFactoryMethod(factoryCandidates);
if (explicitFactory != null) {
return _constructCreatorKeyDeserializer(config, explicitFactory);
}
// If we had implicit Constructor, that'd work now
if (ctorInfo != null) {
return _constructCreatorKeyDeserializer(config, ctorInfo.annotated);
}
// And finally, if any implicit factory methods, acceptable now
// nope, no such luck...
if (!factoryCandidates.isEmpty()) {
// 15-Jun-2021, tatu: Ideally we would provide stabler ordering, but for now
// let's simply pick the first one
return _constructCreatorKeyDeserializer(config, factoryCandidates.get(0).annotated);
}
return null;
}
private static KeyDeserializer _constructCreatorKeyDeserializer(DeserializationConfig config,
AnnotatedMember creator)
{
if (creator instanceof AnnotatedConstructor) {
Constructor rawCtor = ((AnnotatedConstructor) creator).getAnnotated();
if (config.canOverrideAccessModifiers()) {
ClassUtil.checkAndFixAccess(rawCtor, config.isEnabled(MapperFeature.OVERRIDE_PUBLIC_ACCESS_MODIFIERS));
}
return new StdKeyDeserializer.StringCtorKeyDeserializer(rawCtor);
}
Method m = ((AnnotatedMethod) creator).getAnnotated();
if (config.canOverrideAccessModifiers()) {
ClassUtil.checkAndFixAccess(m, config.isEnabled(MapperFeature.OVERRIDE_PUBLIC_ACCESS_MODIFIERS));
}
return new StdKeyDeserializer.StringFactoryKeyDeserializer(m);
}
// 13-Jun-2021, tatu: For now just look for constructor that takes one `String`
// argument (could look for CharSequence) and hence can have just one, no dups
private static AnnotatedAndMetadata _findStringConstructor(BeanDescription beanDesc)
{
for (AnnotatedAndMetadata entry
: beanDesc.getConstructorsWithMode())
{
// BeanDescription method does NOT filter out various types so check
// it takes single argument.
final AnnotatedConstructor ctor = entry.annotated;
if ((ctor.getParameterCount() == 1)
&& (String.class == ctor.getRawParameterType(0))) {
return entry;
}
}
return null;
}
private static AnnotatedMethod _findExplicitStringFactoryMethod(
List> candidates)
throws JsonMappingException
{
AnnotatedMethod match = null;
for (AnnotatedAndMetadata entry : candidates) {
// Note: caller has filtered out invalid candidates; all we need to check are dups
if (entry.metadata != null) {
if (match == null) {
match = entry.annotated;
} else {
// 15-Jun-2021, tatu: Not optimal type or information, but has to do for now
// since we do not get DeserializationContext
Class rawKeyType = entry.annotated.getDeclaringClass();
throw new IllegalArgumentException(
"Multiple suitable annotated Creator factory methods to be used as the Key deserializer for type "
+ClassUtil.nameOf(rawKeyType));
}
}
}
return match;
}
/*
/**********************************************************
/* KeyDeserializers implementation
/**********************************************************
*/
@Override
public KeyDeserializer findKeyDeserializer(JavaType type,
DeserializationConfig config, BeanDescription beanDesc) throws JsonMappingException
{
Class raw = type.getRawClass();
// 23-Apr-2013, tatu: Map primitive types, just in case one was given
if (raw.isPrimitive()) {
raw = ClassUtil.wrapperType(raw);
}
return StdKeyDeserializer.forType(raw);
}
}