Java tutorial
/* * Seldon -- open source prediction engine * ======================================= * Copyright 2011-2015 Seldon Technologies Ltd and Rummble Ltd (http://www.seldon.io/) * ********************************************************************************************** * * Licensed 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 io.seldon.recommendation.baseline.jdo; import io.seldon.api.Constants; import io.seldon.db.jdo.ClientPersistable; import io.seldon.recommendation.baseline.IStaticRecommendationsProvider; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.Map; import java.util.Set; import javax.jdo.Query; import org.apache.commons.lang.StringUtils; public class SqlStaticRecommendationsProvider extends ClientPersistable implements IStaticRecommendationsProvider { public SqlStaticRecommendationsProvider(String clientName) { super(clientName); } @Override public Map<Long, Double> getStaticRecommendations(long userId, Set<Integer> dimensions, int max) { Collection<Object[]> results; Query query; if (dimensions.isEmpty() || (dimensions.size() == 1 && dimensions.iterator().next() == Constants.DEFAULT_DIMENSION)) { String sql = "select item_id,score from recommendations where user_id=? order by score desc"; if (max > 0) sql = sql + " limit " + max; query = getPM().newQuery("javax.jdo.query.SQL", sql); ArrayList<Object> args = new ArrayList<>(); args.add(userId); results = (Collection<Object[]>) query.executeWithArray(args.toArray()); } else { String dimensionsStr = StringUtils.join(dimensions, ","); String sql = "select recs.item_id,score from recommendations recs join item_map_enum ime on (recs.item_id=ime.item_id) join dimension d on (ime.attr_id=d.attr_id and ime.value_id=d.value_id) where dim_id in (" + dimensionsStr + ") and recs.user_id=? order by score desc"; if (max > 0) sql = sql + " limit " + max; query = getPM().newQuery("javax.jdo.query.SQL", sql); ArrayList<Object> args = new ArrayList<>(); args.add(userId); results = (Collection<Object[]>) query.executeWithArray(args.toArray()); } Map<Long, Double> map = new HashMap<>(); for (Object[] res : results) { Long item = (Long) res[0]; Double score = (Double) res[1]; map.put(item, score); } query.closeAll(); return map; } }