Tomcat and MongoDB

When I started with MongoDB I wanted to use it with everybody's old favourite application server, Tomcat.
There is no point reinventing the wheel so I hunted for usage examples.  I struggled to find any best practice implementation, so I decided to hack my own together.

A requirement I had was I had was I wanted to be able to deploy the web app to a range of different environments, so I needed the service to be flexible.  The simplest way I could think of was pulling the config from the application's web.xml file.


The Mongo object instance represents a pool of connections to the database so you will only need one object of class Mongo even with multiple threads.

web.xml snippet:


MongoService snippet:


Then from the data access object you can specify and authenticate to the relevant DB.

XxxDAO snippet:


This has been working like a dream for me proving to be an extremely convenient way to easily connect to Mongo.

Simple mongodb equivalents

After making a noob error today, I realised that some of the documentation could use a boost.

By default mongo returns the entire document.

All fields for the matched document will be returned

And in java



To return only certain fields, you need to let mongo know which ones you want


The will only return the fields meh and feh from the matched document

And in Java


You can also say 'all fields except for...'



This will return all the fields in the matched document expect for meh

And in Java