Java tutorial
package week1; /* * Copyright (c) 2008 - 2013 10gen, Inc. <http://10gen.com> * * 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. * */ import com.mongodb.AggregationOutput; import com.mongodb.BasicDBObject; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.DBObject; import com.mongodb.MongoClient; import com.mongodb.ServerAddress; import freemarker.template.Configuration; import freemarker.template.Template; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import spark.Request; import spark.Response; import spark.Route; import spark.Spark; import java.io.StringWriter; import java.net.UnknownHostException; import java.util.HashMap; import java.util.Map; public class Week1Homework4 { private static final Logger logger = LoggerFactory.getLogger("logger"); public static void main(String[] args) throws UnknownHostException { final Configuration configuration = new Configuration(); configuration.setClassForTemplateLoading(Week1Homework4.class, "/"); MongoClient client = new MongoClient(new ServerAddress("localhost", 27017)); DB database = client.getDB("m101"); final DBCollection collection = database.getCollection("funnynumbers"); Spark.get(new Route("/") { @Override public Object handle(final Request request, final Response response) { StringWriter writer = new StringWriter(); try { Template helloTemplate = configuration.getTemplate("answer.ftl"); // Not necessary yet to understand this. It's just to prove // that you // are able to run a command on a mongod server AggregationOutput output = collection.aggregate( new BasicDBObject("$group", new BasicDBObject("_id", "$value").append("count", new BasicDBObject("$sum", 1))), new BasicDBObject("$match", new BasicDBObject("count", new BasicDBObject("$lte", 2))), new BasicDBObject("$sort", new BasicDBObject("_id", 1))); int answer = 0; for (DBObject doc : output.results()) { answer += (Double) doc.get("_id"); } Map<String, String> answerMap = new HashMap<String, String>(); answerMap.put("answer", Integer.toString(answer)); helloTemplate.process(answerMap, writer); } catch (Exception e) { logger.error("Failed", e); halt(500); } return writer; } }); } }