Java MongoDB Connection

package com.mkyong.core; import java.net.UnknownHostException; import java.util.ArrayList; import java.util.Calendar; import java.util.List; import com.mongodb.BasicDBObject; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.DBCursor; import com.mongodb.DBObject; import com.mongodb.Mongo; import com.mongodb.MongoException; /** * Java MongoDB : Query document * * @author mkyong * */ public class QueryApp { public static void insertDummyDocuments(DBCollection collection) { List<DBObject> dbObjects = new ArrayList<DBObject>(); Calendar calendar = Calendar.getInstance(); for (int i = 1; i <= 5; i++) { BasicDBObject data = new BasicDBObject(); data.append("number", i); data.append("name", "t4b-doc-" + i); data.append("date", calendar.getTime()); calendar.add(Calendar.DATE, 1); dbObjects.add(data); } collection.insert(dbObjects); } public static void main(String[] args) { try { Mongo mongo = new Mongo("127.0.0.1", 27017); DB db = mongo.getDB("t4b_demodb"); // get collection by name DBCollection collection = db.getCollection("demo_collection"); // insert dummy documents in the collection insertDummyDocuments(collection); System.out.println("Get first matched document"); DBObject dbObject = collection.findOne(); System.out.println(dbObject); System.out.println("Get all matched documents"); DBCursor cursor1 = collection.find(); while (cursor1.hasNext()) { System.out.println(cursor1.next()); } System.out.println("Get 'name' field only"); BasicDBObject allQuery = new BasicDBObject(); BasicDBObject fields = new BasicDBObject(); fields.put("name", 1); DBCursor cursor2 = collection.find(allQuery, fields); while (cursor2.hasNext()) { System.out.println(cursor2.next()); } System.out.println("Get where number = 5"); BasicDBObject whereQuery = new BasicDBObject(); whereQuery.put("number", 5); DBCursor cursor3 = collection.find(whereQuery); while (cursor3.hasNext()) { System.out.println(cursor3.next()); } System.out.println("\nFind where number in 2 and 4"); BasicDBObject inQuery = new BasicDBObject(); List<Integer> list = new ArrayList<Integer>(); list.add(2); list.add(4); inQuery.put("number", new BasicDBObject("$in", list)); DBCursor cursor4 = collection.find(inQuery); while (cursor4.hasNext()) { System.out.println(cursor4.next()); } System.out.println("Get where 2 < number < 5"); BasicDBObject gtQuery = new BasicDBObject(); gtQuery.put("number", new BasicDBObject("$gt", 2).append("$lt", 5)); DBCursor cursor5 = collection.find(gtQuery); while (cursor5.hasNext()) { System.out.println(cursor5.next()); } System.out.println("Get where number != 4"); BasicDBObject neQuery = new BasicDBObject(); neQuery.put("number", new BasicDBObject("$ne", 4)); DBCursor cursor6 = collection.find(neQuery); while (cursor6.hasNext()) { System.out.println(cursor6.next()); } System.out.println("Get when number = 2 and name = 't4b-doc-2' example"); BasicDBObject andQuery = new BasicDBObject(); List<BasicDBObject> obj = new ArrayList<BasicDBObject>(); obj.add(new BasicDBObject("number", 2)); obj.add(new BasicDBObject("name", "t4b-doc-2")); andQuery.put("$and", obj); System.out.println(andQuery.toString()); DBCursor cursor7 = collection.find(andQuery); while (cursor7.hasNext()) { System.out.println(cursor7.next()); } System.out.println("Get where name = 't4b.*-[1-3]', case sensitive example"); BasicDBObject regexQuery = new BasicDBObject(); regexQuery.put("name", new BasicDBObject("$regex", "t4b.*-[1-3]").append("$options", "i")); System.out.println(regexQuery.toString()); DBCursor cursor8 = collection.find(regexQuery); while (cursor8.hasNext()) { System.out.println(cursor8.next()); } // collection.drop(); System.out.println("Done"); } catch (UnknownHostException e) { e.printStackTrace(); } catch (MongoException e) { e.printStackTrace(); } } }

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