rich4j / dropwizard-guice

Adds support for Guice to Dropwizard

Dropwizard-Guice

A simple DropWizard extension for integrating Guice via a bundle. It optionally uses classpath scanning courtesy of the Reflections project to discover resources and more to install into the dropwizard environment upon service start.

Usage

    <dependencies>
        <dependency>
            <groupId>com.hubspot.dropwizard</groupId>
            <artifactId>dropwizard-guice</artifactId>
            <version>0.7.0.2</version>
        </dependency>
    </dependencies>

Simply install a new instance of the bundle during your service initialization

public class HelloWorldApplication extends Application<HelloWorldConfiguration> {

  private GuiceBundle<HelloWorldConfiguration> guiceBundle;

  public static void main(String[] args) throws Exception {
    new HelloWorldApplication().run(args);
  }

  @Override
  public void initialize(Bootstrap<HelloWorldConfiguration> bootstrap) {

    guiceBundle = GuiceBundle.<HelloWorldConfiguration>newBuilder()
      .addModule(new HelloWorldModule())
      .setConfigClass(HelloWorldConfiguration.class)
      .build();

    bootstrap.addBundle(guiceBundle);
  }

  @Override
  public String getName() {
    return "hello-world";
  }

  @Override
  public void run(HelloWorldConfiguration helloWorldConfiguration, Environment environment) throws Exception {
    environment.jersey().register(HelloWorldResource.class);
    environment.lifecycle().manage(bundle.getInjector().getInstance(TemplateHealthCheck.class));
  }
}

Lastly, you can enable auto configuration via package scanning.

public class HelloWorldApplication extends Application<HelloWorldConfiguration> {

  public static void main(String[] args) throws Exception {
    new HelloWorldApplication().run(args);
  }

  @Override
  public void initialize(Bootstrap<HelloWorldConfiguration> bootstrap) {

    GuiceBundle<HelloWorldConfiguration> guiceBundle = GuiceBundle.<HelloWorldConfiguration>newBuilder()
      .addModule(new HelloWorldModule())
      .enableAutoConfig(getClass().getPackage().getName())
      .setConfigClass(HelloWorldConfiguration.class)
      .build();

    bootstrap.addBundle(guiceBundle);
  }

  @Override
  public String getName() {
    return "hello-world";
  }

  @Override
  public void run(HelloWorldConfiguration helloWorldConfiguration, Environment environment) throws Exception {
    // now you don't need to add resources, tasks, healthchecks or providers
    // you must have your health checks inherit from InjectableHealthCheck in order for them to be injected
  }
}

If you are having trouble accessing your Configuration or Environment inside a Guice Module, you could try using a provider.

public class HelloWorldModule extends AbstractModule {

  @Override
  protected void configure() {
    // anything you'd like to configure
  }

  @Provides
  public SomePool providesSomethingThatNeedsConfiguration(HelloWorldConfiguration configuration) {
    return new SomePool(configuration.getPoolName());
  }

  @Provides
  public SomeManager providesSomenthingThatNeedsEnvironment(Environment env) {
    return new SomeManager(env.getSomethingFromHere()));
  }
}

You can also replace the default Guice Injector by implementing your own InjectorFactory. For example if you want to use Governator you can create the following implementation:

public class GovernatorInjectorFactory implements InjectorFactory {

  @Override
  public Injector create( final Stage stage, final List<Module> modules ) {
    return LifecycleInjector.builder().inStage( stage ).withModules( modules ).build()
        .createInjector();
  }
}

and then set the InjectorFactory when initializing the GuiceBundle:

@Override
public void initialize(Bootstrap<HelloWorldConfiguration> bootstrap) {

  GuiceBundle<HelloWorldConfiguration> guiceBundle = GuiceBundle.<HelloWorldConfiguration>newBuilder()
    .addModule(new HelloWorldModule())
    .enableAutoConfig(getClass().getPackage().getName())
    .setConfigClass(HelloWorldConfiguration.class)
    .setInjectorFactory( new GovernatorInjectorFactory() )
    .build();

 bootstrap.addBundle(guiceBundle);
}

Please fork an example project if you'd like to get going right away.

Enjoy!