A template for using java for small one-off projects

The need

Just writing a small java program using maven but executing it independently without maven can be a f**ing chore.

This template does many things

• Uses maven and includes the most common libraries like guava, apache commons-lang3 and commons-io and Jackson objectmapper for json
• Log4j2 is fully configured. That itself can be quite a chore for a new project.
• A Utils class which includes only "pure" functions. No oop bullshit. reading and writing files, json, etc made easy. Dont leave home without it. Check out the Timer class. You can use it to sample throughput.
• When you do mvn clean package, all the dependencies, the project jar file and resources go into target/dependency-jars. This folder is everything you need to run the program without maven.
• The resources are not packaged in the jar files. Rather they are there as-is in the dependency-jars folder so you can just change it and run it. More details below.
• Instead of command line arguments, the main function searches for a settings.json in the classpath. So you can provide rich structure to command line arguments instead of flags on the command line
• Heck, I'm even throwing in a nice .gitignore and a README.md file.

Configure Intellij

The src/main/resources folder (henceforth referred to as the resources folder) contains config files such as log4j2.xml, etc. It should be possible to change these files and rerun without doing a recompile.

The default maven behaviour makes it impossible because the resource folder gets packaged in the main jar.

To workaround this, we make some changes in pom.xml. We exclude resource folder from getting packaged in the jar and copy the contents directly to target/.

Unfortunately, Intellij starts acting up with this change and needs some hand-holding to make it see the light.

Go to file->project structure. Select modules on the left and select the dependencies tab on the right. Click the + sign to add Jars or Directories and select the resources folder. In the choose categories of selected files dialog box, select classes and click ok. You'll see the resources directory added to the bottom. That is it. Now all files in resources directory are recognized as being in the classpath and everything in the world is happy and gay.

To compile

mvn package

To copy it to a remote location (optional)

rsync -zaP target/dependency-jars/ 188.166.204.110:~/code/template

To run it on the remote location

java -cp  '/home/sharath.g/code/template/:/home/sharath.g/code/template/*' sha.App