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Simple MongoDB+Java example

MongoDB is pretty slick for ease of use and scalability. As part of figuring out how to interface with MongoDB, I wrote a simple Java class that gives you an idea about how to create a collection and do CRUD on that. See below. Quite a bit of information is available on the web, but I thought a sample that shows off all the basic things will be useful. Good link - notes from a production mongoDB deployment

 
/**
 * Simple Example that shows creating a people (id:number, name:string,
 * gender:string) collection and then adding, finding, updating and deleting.
 * You need to download and install MongoDB (www.mongodb.org) and run the
 * server. You’ll also need to have the mongo-1.2.jar in your class path.
 */

package org.vsbabu.examples.mongo;

import java.net.UnknownHostException;
import java.util.regex.Pattern;

import com.mongodb.*;

/**
 * @author vsbabu
 */
public class ManagePeople {

	public static void main(String[] args) {

		try {
			Mongo m = new Mongo("localhost", 27017);
			DB db = m.getDB("sampledb");
			DBCollection coll = db.getCollection("people");

			// clear records if any
			DBCursor cur = coll.find();
			while (cur.hasNext())
				coll.remove(cur.next());

			// create a unique ascending index on id; 
			//doesn’t seem to work? it works from python and javascript
			coll.ensureIndex(new BasicDBObject("id", 1).append("unique", true));
			coll.createIndex(new BasicDBObject("name", 1));
			coll.insert(makePersonDocument(6655, "James", "male"));
			coll.insert(makePersonDocument(6797, "Bond", "male"));
			coll.insert(makePersonDocument(6643, "Cheryl", "female"));
			coll.insert(makePersonDocument(7200, "Scarlett", "female"));
			coll.insert(makePersonDocument(6400, "Jacks", "male"));
			System.out.println("Total Records : " + coll.getCount());

			cur = coll.find();
			printResults(cur, "Find All Records");

			cur = coll.find(new BasicDBObject("id", 6655));
			printResults(cur, "Find id = 6655");

			cur = coll.find(new BasicDBObject()
					.append("id", new BasicDBObject("$lte", 6700)));
			printResults(cur, "Find id <= 6700");

			cur = coll.find(new BasicDBObject()
					.append("id", new BasicDBObject("$lte", 6700))
					.append("gender", "male"));
			printResults(cur, "Find id <= 6700 and gender = male");

			cur = coll.find(new BasicDBObject()
					.append("name", Pattern.compile("^ja.*?s$", Pattern.CASE_INSENSITIVE)))
					.sort(new BasicDBObject("name", -1));
			printResults(cur, "Find name like Ja%s and sort reverse by name");
			
			cur = coll.find(new BasicDBObject()
					.append("gender", "female"))
					.sort(new BasicDBObject("id", -1))
					.limit(2);
			printResults(cur, "Get top 2 (by id) ladies");
			
			//let us reduce every body’s phone numbers by 10; add Sir to males, Mme to ladies
			cur  = coll.find();
			while(cur.hasNext()) {
				BasicDBObject set = new BasicDBObject("$inc", new BasicDBObject("id", -10));
				if ("male".equals(cur.next().get("gender")))
					set.append("$set", new BasicDBObject("name", "Sir ".concat((String) cur.curr().get("name"))));
				else
					set.append("$set", new BasicDBObject("name", "Mme ".concat((String) cur.curr().get("name"))));
				coll.update(cur.curr(), set);
			}
			cur  = coll.find();
			printResults(cur, "All, after id and name update");
			
		}
		catch (UnknownHostException ex) {
			ex.printStackTrace();
		}
		catch (MongoException ex) {
			ex.printStackTrace();
		}

	}

	private static void printResults(DBCursor cur, String message) {
		System.out.println("<<<<<<<<<< " + message + " >>>>>>>>>>>>");
		while (cur.hasNext()) {
			System.out.println(cur.next().get("id") + "," + cur.curr().get("name") + "," + cur.curr().get("gender"));
		}
	}

	private static BasicDBObject makePersonDocument(int id, String name, String gender) {
		BasicDBObject doc = new BasicDBObject();
		doc.put("id", id);
		doc.put("name", name);
		doc.put("gender", gender);
		return doc;
	}

}

/* 
Output will look like below
Total Records : 5
<<<<<<<<<< Find All Records >>>>>>>>>>>>
6655,James,male
6797,Bond,male
6643,Cheryl,female
7200,Scarlett,female
6400,Jacks,male
<<<<<<<<<< Find id = 6655 >>>>>>>>>>>>
6655,James,male
<<<<<<<<<< Find id <= 6700 >>>>>>>>>>>>
6400,Jacks,male
6643,Cheryl,female
6655,James,male
<<<<<<<<<< Find id <= 6700 and gender = male >>>>>>>>>>>>
6400,Jacks,male
6655,James,male
<<<<<<<<<< Find name like Ja%s and sort reverse by name >>>>>>>>>>>>
6655,James,male
6400,Jacks,male
<<<<<<<<<< Get top 2 (by id) ladies >>>>>>>>>>>>
7200,Scarlett,female
6643,Cheryl,female
<<<<<<<<<< All, after id and name update >>>>>>>>>>>>
6645,Sir James,male
6787,Sir Bond,male
6633,Mme Cheryl,female
7190,Mme Scarlett,female
6390,Sir Jacks,male
*/