Java 10 modular Springboot 2 Gradle sample application

This is an example Springboot 2 application that uses Java 10, Gradle 4.7, Gradle modules, and Java 10 modules.

You can clone/download, and should be able to run the command: ./gradlew bootRun

Initial setup

To create your own Springboot 2 app, with Java 10 modules, there are a few things you've got to add:

Module path

You ned to add to the compiler you'd like to use modules. The below should be added to your root gradle file in the subproject section.

    // required for modules
    afterEvaluate {
        compileJava {
            inputs.property("moduleName", moduleName)
            doFirst {
                options.compilerArgs = [
                        '--module-path', classpath.asPath
                ]
                classpath = files()
            }
        }
    }

Importing libraries

Using the term implementation seems to be the new thing in gradle. However, you'll probably come across a lot of issues where imported libraries share package names. In this case, you've got to exclude one library to favour another. You can do this by doing the following (though adapt for your library needs):

    implementation("org.springframework.boot:spring-boot-starter-web:${springboot}") {
        exclude(module: 'javax.annotation-api')
        exclude(module: 'java-annotation')
        exclude(module: 'spring-boot-start-logging')
    }

Adding a new module

Adding a new module should be pretty simple. Create a new Gradle module, and in it's build.gradle file, add the following line: ext.moduleName = 'com.your.package.structure' - this should match the name in the module-info.java file. Gradle will complain until you've added this line, so do it early on. Then go ahead and add your module-info.java file.

Added tips and tricks

Spring requires / other libraries

Intellij won't understand a library until it's been added to the module-info.java file. While technically correct, it's a total pain to work with if you don't know what class comes under what package. I've found that if you work without modules, and then add them in, Intellij is smart enough to ask you to add them to your module-info.java. However, trying to convert an existing project to modules can be a bit of a pain. So here's some requires that are needed for basic Springboot usage:

    requires spring.beans;
    requires spring.boot;
    requires spring.web;
    requires spring.boot.autoconfigure;
    requires spring.context;
    requires jackson.annotations;
    requires java.validation;

Contributing

If you'd like to add to this project, raise pull request and I'll get back to you. You can also contact me on twitter

Hazz223/springboot-java-10-gradle