Java - Hot code Swapping on Spring Boot

One of the worst pains in Java is having to stop / start a server at each simple change in the code (reload it).

Pretty much all IDEs provide support for hot code swapping with A LOT of limitations.

To do hot code swapping you must enable debug and then connect from the IDE to the given port:

-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=1044

But what if we want to make more drastic changes in the code?

Well, there is JRebel (a paid solution) and spring loaded (free). So I will cover the free tool =)

So how do we set this up in gradle and Intellij?

Well, first we need to add springloaded to the buildscript:

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:1.4.1.RELEASE")
        classpath 'org.springframework:springloaded:1.2.6.RELEASE'
    }
}

Then we add the idea plugin:

apply plugin: 'idea'

Then we configure the plugin:

idea {
    module {
        inheritOutputDirs = false
        outputDir = file("$buildDir/classes/main/")
    }
}

Then add or refresh the gradle configurations in Intellij, and enable “Make project automatically” so you don’t have to press CTRL+F9 each time you want to reload code.