DeserializerCache (jackson-databind 2.16.1)

java.lang.Object
- com.fasterxml.jackson.databind.deser.DeserializerCache

All Implemented Interfaces:

Serializable
```
public final class DeserializerCache
extends Object
implements Serializable
```
Class that defines caching layer between callers (like ObjectMapper, DeserializationContext) and classes that construct deserializers (DeserializerFactory).

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type	Field and Description
`protected LookupCache<JavaType,JsonDeserializer<Object>>`	`_cachedDeserializers` We will also cache some dynamically constructed deserializers; specifically, ones that are expensive to construct.
`protected HashMap<JavaType,JsonDeserializer<Object>>`	`_incompleteDeserializers` During deserializer construction process we may need to keep track of partially completed deserializers, to resolve cyclic dependencies.
`static int`	`DEFAULT_MAX_CACHE_SIZE` Default size of the underlying cache to use.

Constructor Summary

Constructors
Constructor and Description

DeserializerCache()

DeserializerCache(int maxSize)

DeserializerCache(LookupCache<JavaType,JsonDeserializer<Object>> cache)

Constructors
Constructor and Description
`DeserializerCache()`
`DeserializerCache(int maxSize)`
`DeserializerCache(LookupCache<JavaType,JsonDeserializer<Object>> cache)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`protected JsonDeserializer<Object>`	`_createAndCache2(DeserializationContext ctxt, DeserializerFactory factory, JavaType type)` Method that handles actual construction (via factory) and caching (both intermediate and eventual)
`protected JsonDeserializer<Object>`	`_createAndCacheValueDeserializer(DeserializationContext ctxt, DeserializerFactory factory, JavaType type)` Method that will try to create a deserializer for given type, and resolve and cache it if necessary
`protected JsonDeserializer<Object>`	`_createDeserializer(DeserializationContext ctxt, DeserializerFactory factory, JavaType type)` Method that does the heavy lifting of checking for per-type annotations, find out full type, and figure out which actual factory method to call.
`protected JsonDeserializer<?>`	`_createDeserializer2(DeserializationContext ctxt, DeserializerFactory factory, JavaType type, BeanDescription beanDesc)`
`protected JsonDeserializer<Object>`	`_findCachedDeserializer(JavaType type)`
`protected KeyDeserializer`	`_handleUnknownKeyDeserializer(DeserializationContext ctxt, JavaType type)`
`protected JsonDeserializer<Object>`	`_handleUnknownValueDeserializer(DeserializationContext ctxt, JavaType type)`
`int`	`cachedDeserializersCount()` Method that can be used to determine how many deserializers this provider is caching currently (if it does caching: default implementation does) Exact count depends on what kind of deserializers get cached; default implementation caches only dynamically constructed deserializers, but not eagerly constructed standard deserializers (which is different from how serializer provider works).
`DeserializerCache`	`emptyCopy()`
`protected Converter<Object,Object>`	`findConverter(DeserializationContext ctxt, Annotated a)`
`protected JsonDeserializer<Object>`	`findConvertingDeserializer(DeserializationContext ctxt, Annotated a, JsonDeserializer<Object> deser)` Helper method that will check whether given annotated entity (usually class, but may also be a property accessor) indicates that a `Converter` is to be used; and if so, to construct and return suitable serializer for it.
`protected JsonDeserializer<Object>`	`findDeserializerFromAnnotation(DeserializationContext ctxt, Annotated ann)` Helper method called to check if a class or method has annotation that tells which class to use for deserialization.
`KeyDeserializer`	`findKeyDeserializer(DeserializationContext ctxt, DeserializerFactory factory, JavaType type)` Method called to get hold of a deserializer to use for deserializing keys for `Map`.
`JsonDeserializer<Object>`	`findValueDeserializer(DeserializationContext ctxt, DeserializerFactory factory, JavaType propertyType)` Method called to get hold of a deserializer for a value of given type; or if no such deserializer can be found, a default handler (which may do a best-effort generic serialization or just simply throw an exception when invoked).
`void`	`flushCachedDeserializers()` Method that will drop all dynamically constructed deserializers (ones that are counted as result value for `cachedDeserializersCount()`).
`boolean`	`hasValueDeserializerFor(DeserializationContext ctxt, DeserializerFactory factory, JavaType type)` Method called to find out whether provider would be able to find a deserializer for given type, using a root reference (i.e.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail
- DEFAULT_MAX_CACHE_SIZE
```
public static final int DEFAULT_MAX_CACHE_SIZE
```
  Default size of the underlying cache to use.
  
  Since:
  
  2.16
  
  See Also:
  
  Constant Field Values
- _cachedDeserializers
```
protected final LookupCache<JavaType,JsonDeserializer<Object>> _cachedDeserializers
```
  We will also cache some dynamically constructed deserializers; specifically, ones that are expensive to construct. This currently means bean, Enum and container deserializers.
- _incompleteDeserializers
```
protected final HashMap<JavaType,JsonDeserializer<Object>> _incompleteDeserializers
```
  During deserializer construction process we may need to keep track of partially completed deserializers, to resolve cyclic dependencies. This is the map used for storing deserializers before they are fully complete.

Constructor Detail

DeserializerCache
```
public DeserializerCache()
```

DeserializerCache
```
public DeserializerCache(int maxSize)
```

DeserializerCache

public DeserializerCache(LookupCache<JavaType,JsonDeserializer<Object>> cache)

Since:: 2.16

Method Detail

emptyCopy
```
public DeserializerCache emptyCopy()
```
Since:

2.16

cachedDeserializersCount
```
public int cachedDeserializersCount()
```
Method that can be used to determine how many deserializers this provider is caching currently (if it does caching: default implementation does) Exact count depends on what kind of deserializers get cached; default implementation caches only dynamically constructed deserializers, but not eagerly constructed standard deserializers (which is different from how serializer provider works).
The main use case for this method is to allow conditional flushing of deserializer cache, if certain number of entries is reached.

flushCachedDeserializers
```
public void flushCachedDeserializers()
```
Method that will drop all dynamically constructed deserializers (ones that are counted as result value for cachedDeserializersCount()). This can be used to remove memory usage (in case some deserializers are only used once or so), or to force re-construction of deserializers after configuration changes for mapper than owns the provider.

findValueDeserializer
```
public JsonDeserializer<Object> findValueDeserializer(DeserializationContext ctxt,
                                                      DeserializerFactory factory,
                                                      JavaType propertyType)
                                               throws JsonMappingException
```
Method called to get hold of a deserializer for a value of given type; or if no such deserializer can be found, a default handler (which may do a best-effort generic serialization or just simply throw an exception when invoked).
Note: this method is only called for value types; not for keys. Key deserializers can be accessed using findKeyDeserializer(com.fasterxml.jackson.databind.DeserializationContext, com.fasterxml.jackson.databind.deser.DeserializerFactory, com.fasterxml.jackson.databind.JavaType).
Note also that deserializer returned is guaranteed to be resolved (if it is of type ResolvableDeserializer), but not contextualized (wrt ContextualDeserializer): caller has to handle latter if necessary.

Parameters:

ctxt - Deserialization context

propertyType - Declared type of the value to deserializer (obtained using 'setter' method signature and/or type annotations

Throws:

JsonMappingException - if there are fatal problems with accessing suitable deserializer; including that of not finding any serializer

findKeyDeserializer

public KeyDeserializer findKeyDeserializer(DeserializationContext ctxt,
                                           DeserializerFactory factory,
                                           JavaType type)
                                    throws JsonMappingException

Method called to get hold of a deserializer to use for deserializing keys for Map.

Throws:: JsonMappingException - if there are fatal problems with accessing suitable key deserializer; including that of not finding any serializer

hasValueDeserializerFor

public boolean hasValueDeserializerFor(DeserializationContext ctxt,
                                       DeserializerFactory factory,
                                       JavaType type)
                                throws JsonMappingException

Method called to find out whether provider would be able to find a deserializer for given type, using a root reference (i.e. not through fields or membership in an array or collection)

Throws:: JsonMappingException

_findCachedDeserializer

protected JsonDeserializer<Object> _findCachedDeserializer(JavaType type)

_createAndCacheValueDeserializer

protected JsonDeserializer<Object> _createAndCacheValueDeserializer(DeserializationContext ctxt,
                                                                    DeserializerFactory factory,
                                                                    JavaType type)
                                                             throws JsonMappingException

Method that will try to create a deserializer for given type, and resolve and cache it if necessary

Parameters:: ctxt - Currently active deserialization context; type - Type of property to deserialize
Throws:: JsonMappingException

_createAndCache2

protected JsonDeserializer<Object> _createAndCache2(DeserializationContext ctxt,
                                                    DeserializerFactory factory,
                                                    JavaType type)
                                             throws JsonMappingException

Method that handles actual construction (via factory) and caching (both intermediate and eventual)

Throws:: JsonMappingException

_createDeserializer

protected JsonDeserializer<Object> _createDeserializer(DeserializationContext ctxt,
                                                       DeserializerFactory factory,
                                                       JavaType type)
                                                throws JsonMappingException

Method that does the heavy lifting of checking for per-type annotations, find out full type, and figure out which actual factory method to call.

Throws:: JsonMappingException

_createDeserializer2

protected JsonDeserializer<?> _createDeserializer2(DeserializationContext ctxt,
                                                   DeserializerFactory factory,
                                                   JavaType type,
                                                   BeanDescription beanDesc)
                                            throws JsonMappingException

Throws:: JsonMappingException

findDeserializerFromAnnotation

protected JsonDeserializer<Object> findDeserializerFromAnnotation(DeserializationContext ctxt,
                                                                  Annotated ann)
                                                           throws JsonMappingException

Helper method called to check if a class or method has annotation that tells which class to use for deserialization. Returns null if no such annotation found.

Throws:: JsonMappingException

findConvertingDeserializer

protected JsonDeserializer<Object> findConvertingDeserializer(DeserializationContext ctxt,
                                                              Annotated a,
                                                              JsonDeserializer<Object> deser)
                                                       throws JsonMappingException

Helper method that will check whether given annotated entity (usually class, but may also be a property accessor) indicates that a Converter is to be used; and if so, to construct and return suitable serializer for it. If not, will simply return given serializer as is.

Throws:: JsonMappingException

findConverter

protected Converter<Object,Object> findConverter(DeserializationContext ctxt,
                                                 Annotated a)
                                          throws JsonMappingException

Throws:: JsonMappingException

_handleUnknownValueDeserializer

protected JsonDeserializer<Object> _handleUnknownValueDeserializer(DeserializationContext ctxt,
                                                                   JavaType type)
                                                            throws JsonMappingException

Throws:: JsonMappingException

_handleUnknownKeyDeserializer

protected KeyDeserializer _handleUnknownKeyDeserializer(DeserializationContext ctxt,
                                                        JavaType type)
                                                 throws JsonMappingException

Throws:: JsonMappingException

Class DeserializerCache

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_MAX_CACHE_SIZE

_cachedDeserializers

_incompleteDeserializers

Constructor Detail

DeserializerCache

DeserializerCache

DeserializerCache

Method Detail

emptyCopy

cachedDeserializersCount

flushCachedDeserializers

findValueDeserializer

findKeyDeserializer

hasValueDeserializerFor

_findCachedDeserializer

_createAndCacheValueDeserializer

_createAndCache2

_createDeserializer

_createDeserializer2

findDeserializerFromAnnotation

findConvertingDeserializer

findConverter

_handleUnknownValueDeserializer

_handleUnknownKeyDeserializer