Java tutorial
/* * 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. */ package org.apache.pirk.query.wideskies; import com.google.gson.Gson; 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; import com.google.gson.reflect.TypeToken; import org.apache.pirk.schema.query.QuerySchema; import org.apache.pirk.schema.query.filter.DataFilter; import org.apache.pirk.schema.query.filter.FilterFactory; import org.apache.pirk.utils.PIRException; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.IOException; import java.lang.reflect.Type; import java.math.BigInteger; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Set; import java.util.SortedMap; import java.util.UUID; /** * Custom deserializer for Query class for Gson. */ public class QueryDeserializer implements JsonDeserializer<Query> { private static final Logger logger = LoggerFactory.getLogger(QueryDeserializer.class); private static final Gson gson = new Gson(); @Override public Query deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException { JsonObject jsonObject = jsonElement.getAsJsonObject(); logger.info("Got query json:" + jsonObject.toString()); // Check the version number. long queryVersion = jsonObject.get("queryVersion").getAsLong(); if (queryVersion != Query.querySerialVersionUID) { throw new JsonParseException("Attempt to deserialize unsupported query version. Supported: " + Query.querySerialVersionUID + "; Received: " + queryVersion); } // Then deserialize the Query Info QueryInfo queryInfo = deserializeInfo(jsonObject.get("queryInfo").getAsJsonObject()); SortedMap<Integer, BigInteger> queryElements = gson.fromJson(jsonObject.get("queryElements"), new TypeToken<SortedMap<Integer, BigInteger>>() { }.getType()); BigInteger N = new BigInteger(jsonObject.get("n").getAsString()); BigInteger NSquared = new BigInteger(jsonObject.get("nsquared").getAsString()); Map<Integer, String> expFileBasedLookup = gson.fromJson(jsonObject.get("expFileBasedLookup"), new TypeToken<Map<Integer, String>>() { }.getType()); Query query = new Query(queryInfo, N, NSquared, queryElements); query.setExpFileBasedLookup(expFileBasedLookup); return query; } /** * Deserializes a QueryInfo JsonObject * * @param queryInfoJson * A JsonObject at the root of a serialized QueryInfo object. * @return A QueryInfo object of the deserialized Json. * @throws JsonParseException */ public static QueryInfo deserializeInfo(JsonObject queryInfoJson) throws JsonParseException { // First check the version. long infoVersion = queryInfoJson.get("queryInfoVersion").getAsLong(); if (infoVersion != QueryInfo.queryInfoSerialVersionUID) { throw new JsonParseException("Attempt to deserialize unsupported query info version. Supported: " + QueryInfo.queryInfoSerialVersionUID + "; Received: " + infoVersion); } // Deserialize the QuerySchema next, accounting for the possibility that it is null. QuerySchema querySchema; if (queryInfoJson.get("qSchema").isJsonNull()) { querySchema = null; } else { querySchema = deserializeSchema(queryInfoJson.get("qSchema").getAsJsonObject()); } // Now start making the QueryInfo object. QueryInfo info = new QueryInfo(UUID.fromString(queryInfoJson.get("identifier").getAsString()), queryInfoJson.get("numSelectors").getAsInt(), queryInfoJson.get("hashBitSize").getAsInt(), queryInfoJson.get("hashKey").getAsString(), queryInfoJson.get("dataPartitionBitSize").getAsInt(), queryInfoJson.get("queryType").getAsString(), queryInfoJson.get("useExpLookupTable").getAsBoolean(), queryInfoJson.get("embedSelector").getAsBoolean(), queryInfoJson.get("useHDFSExpLookupTable").getAsBoolean(), queryInfoJson.get("numBitsPerDataElement").getAsInt(), querySchema); return info; } /** * Deserializes a QuerySchema JsonObject * * @param querySchemaJson * A JsonObject at the root of a serialized QuerySchema object. * @return A QuerySchema object of the deserialized Json. * @throws JsonParseException */ private static QuerySchema deserializeSchema(JsonObject querySchemaJson) throws JsonParseException { // Deserialize The Query Schema First. long schemaVersion = querySchemaJson.get("querySchemaVersion").getAsLong(); if (schemaVersion != QuerySchema.querySchemaSerialVersionUID) { throw new JsonParseException("Attempt to deserialize unsupported query info version. Supported: " + QueryInfo.queryInfoSerialVersionUID + "; Received: " + schemaVersion); } String dataFilterName = querySchemaJson.get("filterTypeName").getAsString(); Set<String> filteredElementNames; try { filteredElementNames = gson.fromJson(querySchemaJson.get("filteredElementNames"), new TypeToken<Set<String>>() { }.getType()); } catch (Exception e) { logger.warn("No filtered element names for Query Schema deserialization."); filteredElementNames = null; } // Set up the data filter DataFilter dataFilter; try { dataFilter = FilterFactory.getFilter(dataFilterName, filteredElementNames); } catch (IOException | PIRException e) { logger.error("Error trying to create data filter from JSON.", e); throw new JsonParseException(e); } QuerySchema querySchema = new QuerySchema(querySchemaJson.get("schemaName").getAsString(), querySchemaJson.get("dataSchemaName").getAsString(), querySchemaJson.get("selectorName").getAsString(), dataFilterName, dataFilter, querySchemaJson.get("dataElementSize").getAsInt()); List<String> elementNames = gson.fromJson(querySchemaJson.get("elementNames"), new TypeToken<List<String>>() { }.getType()); querySchema.getElementNames().addAll(elementNames); HashMap<String, String> additionalFields = gson.fromJson(querySchemaJson.get("additionalFields"), new TypeToken<HashMap<String, String>>() { }.getType()); querySchema.getAdditionalFields().putAll(additionalFields); return querySchema; } }