JARs and Clojure

October 05, 2021

👋 Hello again!!

Today and in the next couple of week we will be looking into crating our java socet server into a library in the form of a .jar and using it in clojure to host our tic tac toe clojure game in the server!

Creating a JAR library

I’ve been using gradle as my package manager for the clean java socket server. Today I learned how to leverage this powerful library to generate a executable .jar for us to use in our clojure namespace.

Running ./gradlew build straight from the cli gave us these errors:

clean.socket.CleanServerTest > rendersPngFile FAILED
    java.net.ConnectException at CleanServerTest.java:65
        Caused by: java.net.ConnectException at SocketChannelImpl.java:-2

clean.socket.CleanServerTest > rendersGifFile FAILED
    java.net.ConnectException at CleanServerTest.java:81
        Caused by: java.net.ConnectException at SocketChannelImpl.java:-2

🤔

Apparently our build executes our test before the build, that was nice but unexpected. In order to make the test pass I ran the server on another terminal process and tada 🎉:

BUILD SUCCESSFUL in 3s
7 actionable tasks: 2 executed, 5 up-to-date

The output of our jar file was in our app/build/libs/app.jar 😎.

Using our new jar library in our tic-tac-toe clojure namespace

Easisest way I found how to do this was to run create a new lib folder in our clojure tic tac toe project called lib. In it I just inserted our app.jar file.

In our lein project we added:

  :resource-paths ["lib/app.jar"]

And to test if this worked we ran our repl lein repl and tried using the our clen socket server class.

user=> (def app (clean.socket.CleanServer.))
#'user/app
user=> (.start app 3000)
Server Starting!!!

Awesome! ✌️

❤️

Written by Edgardo Carreras.