spring-bridge-maven

This project is library that allows injecting Spring Beans into maven's DI system, Sisu.
It is intended to help maven plugin developments by allowing the usage of spring libraries.
It uses Spring-Guice to brigde the two systems, and allows the usage of spring beans via JSR-330 annotations within the plugin in development.
To see how to use JSR-330 annotations, this documentation is a good start.

⚠️ Beware, there is an important declaration on this wiki about plugins. Hence we need to activate a maven extension so the library can work. See below for more details on how to use the library.

How to use it ?

Let's say you are building a plugin like below

@Mojo(name = "hello")
public class MyMojo extends AbstractMojo {

    @Inject
    private final MyHelloer myFriend;
    
    public void execute() {
        myFriend.hello();
    }

}

You want to use a class that implements MyHelloer interface, coming from a spring library.

1. Add the extension

You should add the extension below in the extensions.xml file located in the maven config folder .mvn of the application (the application that will use the plugin you are developing).
This will allow our library to work, hence your plugin will be able to use spring libraries.

<extensions xmlns="http://maven.apache.org/EXTENSIONS/1.0.0"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://maven.apache.org/EXTENSIONS/1.0.0 http://maven.apache.org/xsd/core-extensions-1.0.0.xsd">
    <extension>
        <groupId>com.homeofthewizard</groupId>
        <artifactId>guice-exporter-maven-extension</artifactId>
        <version>1.0.1-alpha</version>
    </extension>
</extensions>

You can see how to use extensions in more details here.

2. Add an annotation

Somewhere in your plugin add @SpringBootPlugin pointing to the main configuration class of the spring library you want to use. As you can guess, this defines the configuration sources for the the spring application context to be used in the plugin. You can specify a class with @EnableAutoConfiguration annotation, or just a plain @Configuration class. There is an APT processor in the library that writes these out to spring.factories for use at runtime.

3. Add a configuration file

Create an application.properties file like below

friend.name=Bob

Here our example library takes a property as parameter to create a MyFriend Bean (implementing MyHelloer interface).

Place this under src/main/resources folder. This is the default place Spring Boot will look it up as normal.

4. Add the extension as a dependency of your plugin

This is necessary for classpath sharing.
In your plugin's pom.xml

    ...
    <dependencies>
        ...
        <!-- the bridge library -->
        <dependency>
            <groupId>com.homeofthewizard</groupId>
            <artifactId>spring-bridge-maven</artifactId>
            <version>1.0.1-alpha</version>
        </dependency>
        <!-- your spring library -->
        <dependency>
            <groupId>com.people</groupId>
            <artifactId>friends-lib</artifactId>
            <version>1.0</version>
        </dependency>
        ...
    </dependencies>
    ...

Now you can build your plugin.

That is it! You are good to go 🚀

When you run your plugin, the Bean will be automatically injected into it.