ENAR - MongoDB on Heroku

HelloServlet.java

package com.example;

import java.io.IOException;
import java.net.URI;
import java.net.UnknownHostException;
import java.util.Set;
import java.util.logging.Logger;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.MongoURI;

public class HelloServlet extends HttpServlet {

	@Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        ServletOutputStream out = resp.getOutputStream();
        
        DB db = openConnection();
        
        // write
        DBCollection coll = db.getCollection("test");
        coll.insert(new BasicDBObject().append("changenum", "third"));
        
        // read all
        DBCursor cursor = coll.find();
        
        out.write(("This is my " + cursor.next().get("changenum") + " change").getBytes());
        out.flush();
        out.close();
    }

	private DB openConnection() throws UnknownHostException {
		MongoURI mongoURI = new MongoURI(System.getenv("MONGOHQ_URL"));
        DB db = mongoURI.connectDB();
        db.authenticate(mongoURI.getUsername(), mongoURI.getPassword());
		return db;
	}
    
}

pom.xml

<dependency>
	<groupId>org.mongodb</groupId>
	<artifactId>mongo-java-driver</artifactId>
	<version>2.9.1</version>
</dependency> 	

Don't forget to add a MongoDB add-on to your Heroku app! I used the Mongo HQ add-on.