#java freemarker

[techkrab]

W16

Java

Avatar Icon With Freemarker

This week was one of my tasks creation of user avatar icon based on user name initials. Project is based on JVM so I naturally search for Java based library for this task. And I was not successful. There are many solutions from world of node.js or ruby but nothing for Java. Sad.

So, at first I start writing own library generating SVG image with user initials. I was creating services, templates and rest controller for handling icon requests... and it was wrong. Result was complex and requires lot of implementation. Simply it was anything but not designed by KISS.

What was the right solution? Simple freemarker macro generating custom SVG code:

Usage looks like this:

And result of these 6 lines looks perfect:

[nofatclips]

Java and Mongo and Spark and Freemarker 101

And to finally put the M in MVC, let's do the same but now reading the "world" part of our HTML page from a document stored in a MongoDB collection.

https://gist.github.com/nofatclips/5597919

Since the DBObject implements the Map interface, it can be passed directly to Freemarker.

[nofatclips]

Java and Spark and Freemarker 101

We managed to send a string of text to the browser using Spark and to create an HTML string from a template using Freemarker, so the next step is to mix the two to get the VC in MVC working.

https://gist.github.com/nofatclips/5597613

The code is pretty bad, just a mish mash of the previous two, no effort was made to make it something better than that.

[nofatclips]

Java and Freemarker 101

Using Freemarker can be very simple, even though the dynamic template loading requires a little configuration.

https://gist.github.com/nofatclips/5594716

The template is stored under /resources and Maven should take care of including it in the build.

Once dealt with the Configuration, pretty much boilerplate, you just load the template, setup a Map with the values to fill in the blanks and call the process() method passing a Stream for the output.

[nofatclips]

The V in Templating

We still need a saner way to handle views than returning strings of HTML. Following the M101J course, I'm installing Freemarker, a very simple templating engine.

The dependencies details for Maven can be found on the artifact page:

<dependency>     <groupId>org.freemarker</groupId>     <artifactId>freemarker</artifactId>     <version>2.3.19</version> </dependency>

and since it resides on the central Maven repo like Java Mongo, that's pretty much everything.

We're ready for yet another Hello World class.