Java tutorial
/** * Copyright (C) 2016 Czech Technical University in Prague * <p> * This program is free software: you can redistribute it and/or modify it under * the terms of the GNU General Public License as published by the Free Software * Foundation, either version 3 of the License, or (at your option) any * later version. * <p> * This program is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more * details. You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ package cz.cvut.kbss.jsonld.jackson.deserialization; import com.fasterxml.jackson.core.JsonParser; import com.fasterxml.jackson.core.JsonToken; import com.fasterxml.jackson.core.type.TypeReference; import com.fasterxml.jackson.databind.DeserializationContext; import com.fasterxml.jackson.databind.DeserializationFeature; import com.fasterxml.jackson.databind.JsonDeserializer; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.deser.std.DelegatingDeserializer; import com.github.jsonldjava.core.JsonLdError; import com.github.jsonldjava.core.JsonLdProcessor; import cz.cvut.kbss.jsonld.ConfigParam; import cz.cvut.kbss.jsonld.Configuration; import cz.cvut.kbss.jsonld.deserialization.JsonLdDeserializer; import cz.cvut.kbss.jsonld.exception.JsonLdDeserializationException; import java.io.IOException; import java.util.List; import java.util.Map; public class JacksonJsonLdDeserializer extends DelegatingDeserializer { private ObjectMapper mapper = new ObjectMapper(); private final Class<?> resultType; public JacksonJsonLdDeserializer(JsonDeserializer<?> delegatee, Class<?> resultType) { super(delegatee); this.resultType = resultType; } @Override protected JsonDeserializer<?> newDelegatingInstance(JsonDeserializer<?> newDelegatee) { // TODO Is the null ok? Perhaps we should use a different base class, we are not delegating deserialization to anything else anyway return new JacksonJsonLdDeserializer(newDelegatee, null); } @Override public Object deserialize(JsonParser jp, DeserializationContext ctx) throws IOException { try { final Object input = parseJsonObject(jp); final List<Object> expanded = JsonLdProcessor.expand(input); final JsonLdDeserializer deserializer = JsonLdDeserializer.createExpandedDeserializer(configure(ctx)); return deserializer.deserialize(expanded, resultType); } catch (JsonLdError e) { throw new JsonLdDeserializationException("Unable to expand the input JSON.", e); } } private Configuration configure(DeserializationContext context) { final Configuration config = new Configuration(); if (!context.isEnabled(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)) { config.set(ConfigParam.IGNORE_UNKNOWN_PROPERTIES, Boolean.TRUE.toString()); } return config; } private Object parseJsonObject(JsonParser parser) throws IOException { Object value = null; final JsonToken initialToken = parser.getCurrentToken(); parser.setCodec(mapper); if (initialToken == JsonToken.START_ARRAY) { value = parser.readValueAs(new TypeReference<List<?>>() { }); } else if (initialToken == JsonToken.START_OBJECT) { value = parser.readValueAs(new TypeReference<Map<?, ?>>() { }); } else if (initialToken == JsonToken.VALUE_STRING) { value = parser.readValueAs(String.class); } else if (initialToken == JsonToken.VALUE_FALSE || initialToken == JsonToken.VALUE_TRUE) { value = parser.readValueAs(Boolean.class); } else if (initialToken == JsonToken.VALUE_NUMBER_FLOAT || initialToken == JsonToken.VALUE_NUMBER_INT) { value = parser.readValueAs(Number.class); } else if (initialToken == JsonToken.VALUE_NULL) { value = null; } return value; } }