Java tutorial
package org.apache.tika.metadata.serialization; /* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.lang.reflect.Type; import java.util.Iterator; import java.util.Map; import org.apache.tika.metadata.Metadata; import com.google.gson.JsonArray; import com.google.gson.JsonDeserializationContext; import com.google.gson.JsonDeserializer; import com.google.gson.JsonElement; import com.google.gson.JsonObject; import com.google.gson.JsonParseException; /** * Deserializer for Metadata * * If overriding this, remember that this is called from a static context. * Share state only with great caution. */ public class JsonMetadataDeserializer implements JsonDeserializer<Metadata> { /** * Deserializes a json object (equivalent to: Map<String, String[]>) * into a Metadata object. * * @param element to serialize * @param type (ignored) * @param context (ignored) * @return Metadata * @throws JsonParseException if element is not able to be parsed */ @Override public Metadata deserialize(JsonElement element, Type type, JsonDeserializationContext context) throws JsonParseException { final JsonObject obj = element.getAsJsonObject(); Metadata m = new Metadata(); for (Map.Entry<String, JsonElement> entry : obj.entrySet()) { String key = entry.getKey(); JsonElement v = entry.getValue(); if (v.isJsonPrimitive()) { m.set(key, v.getAsString()); } else if (v.isJsonArray()) { JsonArray vArr = v.getAsJsonArray(); Iterator<JsonElement> itr = vArr.iterator(); while (itr.hasNext()) { JsonElement valueItem = itr.next(); m.add(key, valueItem.getAsString()); } } } return m; } }