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Spring Boot Project Examples

This page contains examples of providing Mill as a build tool for Spring Boot applications, adapting the official Spring Boot documentation in increasing complexity.

Spring Boot Web with Initializr

build.mill (download, browse)
package build

import mill.*
import mill.javalib.*
import mill.kotlinlib.KotlinMavenModule

object `package` extends KotlinMavenModule {

  def kotlinVersion = "1.9.25"

  override def kotlincOptions: T[Seq[String]] = super.kotlincOptions() ++ Seq("-jvm-target", "17")

  def mvnDeps = Seq(
    mvn"com.fasterxml.jackson.module:jackson-module-kotlin:2.19.2",
    mvn"org.jetbrains.kotlin:kotlin-reflect:1.9.25",
    mvn"org.jetbrains.kotlin:kotlin-stdlib:1.9.25",
    mvn"org.springframework.boot:spring-boot-starter-web:3.5.6"
  )

  object test extends KotlinMavenTests, TestModule.Junit5 {

    override def junitPlatformVersion: T[String] = "6.0.0"

    def mvnDeps = Seq(
      mvn"org.jetbrains.kotlin:kotlin-test-junit5:1.9.25",
      mvn"org.springframework.boot:spring-boot-starter-test:3.5.6"
    )

  }
}

This example demonstrates how to configure mill for a simple initializr project, using https://start.spring.io/ by choosing:

  • Project: maven

  • Language: Kotlin

  • Dependencies: Spring Web,

The structure of this project follows the MavenModule structure (i.e. the same structure as generated from the initialzr tool).

For more information visit quickstart and spring-boot-kotlin

> ./mill test
...Test com.example.demokotlin.DemoKotlinApplicationTests#contextLoads() finished...

> ./mill runBackground

> curl http://localhost:9096/hello
...Hello, World!...

> curl http://localhost:9096/hello?name=Mill
...Hello, Mill!...

> ./mill clean runBackground

> ./mill show assembly
.../out/assembly.dest/out.jar...