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Data Mapper package is a high-performance data binding package built on Jackson JSON processor

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package org.codehaus.jackson.map;

import org.codehaus.jackson.type.JavaType;

/**
 * Abstract class that defines API used by {@link ObjectMapper} and
 * {@link JsonDeserializer}s to obtain deserializers capable of
 * re-constructing instances of handled type from JSON content.
 */
public abstract class DeserializerProvider
{
    protected DeserializerProvider() { }

    /*
    /**********************************************************
    /* General deserializer locating method
    /**********************************************************
     */

    /**
     * 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 {@link #findKeyDeserializer}. * * @param type Declared type of the value to deserializer (obtained using * 'setter' method signature and/or type annotations * @param referrer Type that contains the value, if any: null for * root-level object. * @param refPropName Logical name of the property within instance of * referrer, if through a property (field). Null for * Collection and Array types, where reference is not through a * field, as well as for "any property" fallback references * * @throws JsonMappingException if there are fatal problems with * accessing suitable deserializer; including that of not * finding any serializer */ public abstract JsonDeserializer findValueDeserializer(DeserializationConfig config, JavaType type, JavaType referrer, String refPropName) throws JsonMappingException; /** * Method called to locate deserializer for given type, as well as matching * type deserializer (if one is needed); and if type deserializer is needed, * construct a "wrapped" deserializer that can extract and use type information * for calling actual deserializer. *

* Since this method is only called for root elements, no referral information * is taken. * * @since 1.5 */ public abstract JsonDeserializer findTypedValueDeserializer(DeserializationConfig config, JavaType type) throws JsonMappingException; /** * Method called to get hold of a deserializer to use for deserializing * keys for {@link java.util.Map}. * * @throws JsonMappingException if there are fatal problems with * accessing suitable key deserializer; including that of not * finding any serializer */ public abstract KeyDeserializer findKeyDeserializer(DeserializationConfig config, 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) */ public abstract boolean hasValueDeserializerFor(DeserializationConfig config, JavaType type); /* /********************************************************** /* Access to caching aspects /********************************************************** */ /** * 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. * * @since 1.4 */ public abstract int cachedDeserializersCount(); /** * Method that will drop all dynamically constructed deserializers (ones that * are counted as result value for {@link #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. * * @since 1.4 */ public abstract void flushCachedDeserializers(); }