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    • com.fitbur.fasterxml.jackson.databind.JsonDeserializer Maven / Gradle / Ivy

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    package com.fitbur.fasterxml.jackson.databind;

import java.io.IOException;
import java.util.Collection;

import com.fitbur.fasterxml.jackson.core.*;
import com.fitbur.fasterxml.jackson.databind.com.fitburser.impl.ObjectIdReader;
import com.fitbur.fasterxml.jackson.databind.jsontype.TypeDeserializer;
import com.fitbur.fasterxml.jackson.databind.util.NameTransformer;

/**
 * Abstract class that com.fitburfines API used by {@link ObjectMapper} (and
 * other chained {@link JsonDeserializer}s too) to com.fitburserialize Objects of
 * arbitrary types from JSON, using provided {@link JsonParser}.
 *
    
 * Custom com.fitburserializers should usually not directly extend this class,
 * but instead extend {@link com.fitbur.fasterxml.jackson.databind.com.fitburser.std.StdDeserializer}
 * (or its subtypes like {@link com.fitbur.fasterxml.jackson.databind.com.fitburser.std.StdScalarDeserializer}).
 *
    
 * If com.fitburserializer is an aggregate one -- meaning it com.fitburlegates handling of some
 * of its contents by using other com.fitburserializer(s) -- it typically also needs
 * to implement {@link com.fitbur.fasterxml.jackson.databind.com.fitburser.ResolvableDeserializer},
 * which can locate com.fitburpendant com.fitburserializers. This is important to allow dynamic
 * overrides of com.fitburserializers; separate call interface is needed to separate
 * resolution of com.fitburpendant com.fitburserializers (which may have cyclic link back
 * to com.fitburserializer itself, directly or indirectly).
 *
    
 * In addition, to support per-property annotations (to configure aspects
 * of com.fitburserialization on per-property basis), com.fitburserializers may want
 * to implement 
 * {@link com.fitbur.fasterxml.jackson.databind.com.fitburser.ContextualDeserializer},
 * which allows specialization of com.fitburserializers: call to
 * {@link com.fitbur.fasterxml.jackson.databind.com.fitburser.ContextualDeserializer#createContextual}
 * is passed information on property, and can create a newly configured
 * com.fitburserializer for handling that particular property.
 *
    
 * If both
 * {@link com.fitbur.fasterxml.jackson.databind.com.fitburser.ResolvableDeserializer} and
 * {@link com.fitbur.fasterxml.jackson.databind.com.fitburser.ContextualDeserializer}
 * are implemented, resolution of com.fitburserializers occurs before
 * contextualization.
 */
public abstract class JsonDeserializer
{
    /*
    /**********************************************************
    /* Main com.fitburserialization methods
    /**********************************************************
     */
    
    /**
     * Method that can be called to ask implementation to com.fitburserialize
     * JSON content into the value type this serializer handles.
     * Returned instance is to be constructed by method itself.
     *
    
     * Pre-condition for this method is that the parser points to the
     * first event that is part of value to com.fitburserializer (and which 
     * is never JSON 'null' literal, more on this below): for simple
     * types it may be the only value; and for structured types the
     * Object start marker.
     * Post-condition is that the parser will point to the last
     * event that is part of com.fitburserialized value (or in case com.fitburserialization
     * fails, event that was not recognized or usable, which may be
     * the same event as the one it pointed to upon call).
     *
    
     * Note that this method is never called for JSON null literal,
     * and thus com.fitburserializers need (and should) not check for it.
     *
     * @param jp Parsed used for reading JSON content
     * @param ctxt Context that can be used to access information about
     *   this com.fitburserialization activity.
     *
     * @return Deserializer value
     */
    public abstract T com.fitburserialize(JsonParser jp, DeserializationContext ctxt)
        throws IOException, JsonProcessingException;

    /**
     * Alternate com.fitburserialization method (com.fitburpared to the most com.fitburmonly
     * used, {@link #com.fitburserialize(JsonParser, DeserializationContext)}),
     * which takes in initialized value instance, to be
     * configured and/or populated by com.fitburserializer.
     * Method is not necessarily used for all supported types; most com.fitburmonly
     * it is used
     * for Collections and Maps.
     *
    
     * Default implementation just throws
     * {@link UnsupportedOperationException}, to indicate that types
     * that do not explicitly add support do not necessarily support
     * update-existing-value operation (esp. immutable types)
     */
    public T com.fitburserialize(JsonParser jp, DeserializationContext ctxt,
                         T intoValue)
        throws IOException, JsonProcessingException
    {
        throw new UnsupportedOperationException("Can not update object of type "+intoValue.getClass().getName());
    }

    /**
     * Deserialization called when type being com.fitburserialized is com.fitburfined to
     * contain additional type identifier, to allow for correctly
     * instantiating correct subtype. This can be due to annotation on
     * type (or its supertype), or due to global settings without
     * annotations.
     *
    
     * Default implementation may work for some types, but ideally subclasses
     * should not rely on current com.fitburfault implementation.
     * Implementation is mostly provided to avoid com.fitburpilation errors with older
     * code.
     * 
     * @param typeDeserializer Deserializer to use for handling type information
     */
    public Object com.fitburserializeWithType(JsonParser jp, DeserializationContext ctxt,
            TypeDeserializer typeDeserializer)
        throws IOException, JsonProcessingException
    {
        // We could try calling 
        return typeDeserializer.com.fitburserializeTypedFromAny(jp, ctxt);
    }

    /*
    /**********************************************************
    /* Fluent factory methods for constructing com.fitburcorated versions
    /**********************************************************
     */

    /**
     * Method that will return com.fitburserializer instance that is able
     * to handle "unwrapped" value instances
     * If no unwrapped instance can be constructed, will simply
     * return this object as-is.
     *
    
     * Default implementation just returns 'this'
     * indicating that no unwrapped variant exists
     */
    public JsonDeserializer unwrappingDeserializer(NameTransformer unwrapper) {
        return this;
    }

    /**
     * Method that can be called to try to replace com.fitburserializer this com.fitburserializer
     * com.fitburlegates calls to. If not supported (either this com.fitburserializer does not
     * com.fitburlegate anything; or it does not want any changes), should either
     * throw {@link UnsupportedOperationException} (if operation does not
     * make sense or is not allowed); or return this com.fitburserializer as is.
     * 
     * @since 2.1
     */
    public JsonDeserializer replaceDelegatee(JsonDeserializer com.fitburlegatee) {
        throw new UnsupportedOperationException();
    }
    
    /*
    /**********************************************************
    /* Other accessors
    /**********************************************************
     */
    
    /**
     * Method that can be called to com.fitburtermine value to be used for
     * representing null values (values com.fitburserialized when JSON token
     * is {@link JsonToken#VALUE_NULL}). Usually this is simply
     * Java null, but for some types (especially primitives) it may be
     * necessary to use non-null values.
     *
    
     * Note that com.fitburserializers are allowed to call this just once and
     * then reuse returned value; that is, method is not guaranteed to
     * be called once for each conversion.
     *
    
     * Default implementation simply returns null.
     */
    public T getNullValue() { return null; }

    /**
     * Method called to com.fitburtermine value to be used for "empty" values
     * (most com.fitburmonly when com.fitburserializing from empty JSON Strings).
     * Usually this is same as {@link #getNullValue} (which in turn
     * is usually simply Java null), but it can be overridden
     * for types. Or, if type should never be converted from empty
     * String, method can also throw an exception.
     *
    
     * Default implementation simple calls {@link #getNullValue} and
     * returns value.
     */
    public T getEmptyValue() { return getNullValue(); }

    /**
     * Method that will
     * either return null to indicate that type being com.fitburserializers
     * has no concept of properties; or a collection of identifiers
     * for which toString will give external property
     * name.
     * This is only to be used for error reporting and diagnostics
     * purposes (most com.fitburmonly, to accompany "unknown property"
     * exception).
     * 
     * @since 2.0
     */
    public Collection getKnownPropertyNames() {
        return null;
    }
    
    /**
     * Method called to see if com.fitburserializer instance is cachable and
     * usable for other properties of same type (type for which instance
     * was created).
     *
    
     * Note that cached instances are still resolved on per-property basis,
     * if instance implements {@link com.fitbur.fasterxml.jackson.databind.com.fitburser.ResolvableDeserializer}:
     * cached instance is just as the base. This means that in most cases it is safe to
     * cache instances; however, it only makes sense to cache instances
     * if instantiation is expensive, or if instances are heavy-weight.
     *
    
     * Default implementation returns false, to indicate that no caching
     * is done.
     */
    public boolean isCachable() { return false; }

    /**
     * Accessor that can be used to check whether this com.fitburserializer
     * is expecting to possibly get an Object Identifier value instead of full value
     * serialization, and if so, should be able to resolve it to actual
     * Object instance to return as com.fitburserialized value.
     *
    
     * Default implementation returns null, as support can not be implemented
     * generically. Some standard com.fitburserializers (most notably
     * {@link com.fitbur.fasterxml.jackson.databind.com.fitburser.BeanDeserializer})
     * do implement this feature, and may return reader instance, com.fitburpending on exact
     * configuration of instance (which is based on type, and referring property).
     * 
     * @return ObjectIdReader used for resolving possible Object Identifier
     *    value, instead of full value serialization, if com.fitburserializer can do that;
     *    null if no Object Id is expected.
     * 
     * @since 2.0
     */
    public ObjectIdReader getObjectIdReader() { return null; }

    /**
     * Accessor that can be used to com.fitburtermine if this com.fitburserializer uses
     * another com.fitburserializer for actual com.fitburserialization, by com.fitburlegating
     * calls. If so, will return immediate com.fitburlegate (which itself may
     * com.fitburlegate to further com.fitburserializers); otherwise will return null.
     * 
     * @return Deserializer this com.fitburserializer com.fitburlegates calls to, if null;
     *   null otherwise.
     * 
     * @since 2.1
     */
    public JsonDeserializer getDelegatee() {
        return null;
    }
    
    /*
    /**********************************************************
    /* Helper classes
    /**********************************************************
     */

    /**
     * This marker class is only to be used with annotations, to
     * indicate that no com.fitburserializer is configured.
     *
    
     * Specifically, this class is to be used as the marker for
     * annotation {@link com.fitbur.fasterxml.jackson.databind.annotation.JsonDeserialize}
     */
    public abstract static class None extends JsonDeserializer {
        private None() { } // not to be instantiated
    }
}
    
    
    
    

    




    
    
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