javax.json.bind.serializer.JsonbDeserializer Maven / Gradle / Ivy

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package javax.json.bind.serializer;

import javax.json.stream.JsonParser;
import java.lang.reflect.Type;

/**
 * Interface representing a custom deserializer for a given type. It provides a low-level API for java object
 * deserialization from JSON stream using {@link JsonParser}. Unlike {@link javax.json.bind.adapter.JsonbAdapter},
 * which acts more as converter from one java type to another, deserializer provides more fine grained control over
 * deserialization process.
 *
 * {@link DeserializationContext} acts as JSONB runtime, able to deserialize any java object provided.
 *
 * Sample of custom Deserializer:
 *  *     class Box {
 *         public BoxInner boxInnerObject;
 *         public String name;
 *     }
 *
 *     BoxDeserializer implements JsonbDeserializer<Box> {
 *         public Box deserialize(JsonParser parser, DeserializationContext ctx, Type rtType) {
 *             Box = new Box();
 *
 *             while (parser.hasNext()) {
 *                 Event event = parser.next();
 *
 *                 if (event == JsonParser.Event.KEY_NAME && parser.getString().equals("boxInnerObject") {
 *                     // Deserialize inner object
 *                     box.boxInnerObject = ctx.deserialize(BoxInner.class, jsonParser);
 *
 *                 } else if (event == JsonParser.Event.KEY_NAME && parser.getString().equals("name") {
 *                     // Deserialize name property
 *                     parser.next(); // move to VALUE
 *                     box.name = parser.getString();
 *                 }
 *             }
 *
 *             return box;
 *         }
 *     }
 * 
 *
 * Deserializers are registered using {@link javax.json.bind.JsonbConfig#withDeserializers(JsonbDeserializer[])}
 * method or using {@link javax.json.bind.annotation.JsonbTypeDeserializer} annotation on type.
 *
 * @param  Type to bind deserializer for.
 * @see javax.json.bind.JsonbConfig
 * @see javax.json.bind.annotation.JsonbTypeDeserializer
 * @see JsonbSerializer
 * @see javax.json.bind.adapter.JsonbAdapter
 * @since JSON Binding 1.0
 */
public interface JsonbDeserializer {

    /**
     * Deserialize JSON stream into object.
     *
     * @param parser
     *      Json parser.
     * @param ctx
     *      Deserialization context.
     * @param rtType
     *      Type of returned object.
     * @return Deserialized instance.
     */
    T deserialize(JsonParser parser, DeserializationContext ctx, Type rtType);
}