DropwizardEnvironmentModule.java

package com.hubspot.dropwizard.guice;

import com.google.common.base.Optional;
import com.google.inject.*;
import com.google.inject.name.Names;
import io.dropwizard.Configuration;
import io.dropwizard.jetty.MutableServletContextHandler;
import io.dropwizard.setup.Bootstrap;
import io.dropwizard.setup.Environment;
import net.sourceforge.argparse4j.inf.Namespace;

import javax.servlet.ServletContext;

public class DropwizardEnvironmentModule<T extends Configuration> extends AbstractModule {
	private static final String ILLEGAL_DROPWIZARD_MODULE_STATE = "The dropwizard environment has not been set. This is likely caused by trying to access the dropwizard environment during the bootstrap phase or during a non-configured command.";
	private Optional<T> configuration;
	private Optional<Environment> environment;
    private Optional<Namespace> namespace = Optional.absent();
    private Optional<Bootstrap<T>> bootstrap;
	private Class<? super T> configurationClass;

	public DropwizardEnvironmentModule(Class<T> configurationClass) {
		this.configurationClass = configurationClass;
	}

	@Override
	protected void configure() {
		Provider<T> provider = new CustomConfigurationProvider();
        if(configuration.isPresent()){
            bind(configurationClass).toProvider(provider);
            if (configurationClass != Configuration.class) {
                bind(Configuration.class).toProvider(provider);
            }
        }
        if(environment.isPresent()) {
            bindContext("application", environment.get().getApplicationContext());
        }
	}

    /**
     * Bind some of the context objects to be injectable. Annotated with a {@link com.google.inject.name.Names} to
     * prevent collisions for any that the {@link com.google.inject.servlet.ServletModule} may bind later.
     */
    private void bindContext(String name, MutableServletContextHandler context) {
        bind(ServletContext.class)
            .annotatedWith(Names.named(name))
            .toInstance(context.getServletContext());
    }

    @Deprecated
	public void setEnvironmentData(T configuration, Environment environment) {
        setEnvironmentData(null, environment, configuration);
	}

    public void setEnvironmentData(Bootstrap<T> bootstrap,
                                   Environment environment,
                                   T configuration) {
        this.bootstrap = Optional.fromNullable(bootstrap);
        this.configuration = Optional.fromNullable(configuration);
        this.environment = Optional.fromNullable(environment);
    }

    public void setNamespace(Namespace namespace) {
        this.namespace = Optional.fromNullable(namespace);
    }

	@Provides
	public Environment providesEnvironment() {
		if (environment == null || !environment.isPresent()) {
			throw new ProvisionException(ILLEGAL_DROPWIZARD_MODULE_STATE);
		}
		return environment.get();
	}

    @Provides
    public Namespace providesNamespace() {
        if (namespace == null || !namespace.isPresent()) {
            throw new ProvisionException(ILLEGAL_DROPWIZARD_MODULE_STATE);
        }
        return namespace.get();
    }

    /**
     * Note: This is a raw type.  Guice cannot inject the full type due to type erasure
     */
    @Provides
    public Bootstrap providesBootstrap() {
        if (bootstrap == null || !bootstrap.isPresent()) {
            throw new ProvisionException(ILLEGAL_DROPWIZARD_MODULE_STATE);
        }
        return bootstrap.get();
    }

	private class CustomConfigurationProvider implements Provider<T> {
		@Override
		public T get() {
			if (configuration == null || !configuration.isPresent()) {
				throw new ProvisionException(ILLEGAL_DROPWIZARD_MODULE_STATE);
			}
			return configuration.get();
		}
	}
}