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/*
* Copyright 2013 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package ratpack.guice;
import com.google.common.collect.Lists;
import com.google.inject.Binder;
import com.google.inject.Injector;
import com.google.inject.Module;
import com.google.inject.Stage;
import com.google.inject.util.Modules;
import ratpack.config.ConfigObject;
import ratpack.func.Action;
import ratpack.func.Function;
import ratpack.guice.internal.DefaultBindingsSpec;
import ratpack.guice.internal.GuiceUtil;
import ratpack.guice.internal.InjectorRegistryBacking;
import ratpack.guice.internal.RatpackBaseRegistryModule;
import ratpack.handling.Chain;
import ratpack.handling.Context;
import ratpack.handling.Handler;
import ratpack.impose.Impositions;
import ratpack.registry.Registry;
import ratpack.server.ServerConfig;
import java.util.List;
import java.util.Optional;
import static com.google.inject.Guice.createInjector;
import static ratpack.util.Exceptions.uncheck;
/**
* Static utility methods for creating Google Guice based Ratpack infrastructure.
*
* Any non trivial application will require supporting objects for the handler implementations, for persistence for example.
* These supporting objects can be managed by Guice and made available to handlers (either by dependency injection or registry lookup)
* for increased reusability, modularity and testability.
*
* The Guice integration is not part of the Ratpack core library, but is available as a separate add on.
* That said, Ratpack is designed to support something like Guice as an integral piece via it's {@link Registry} abstraction.
* Guice is the “official” solution.
*
* Starting a Guice Ratpack app
*
* Below is a complete example for bootstrapping a Guice based Ratpack application.
*
* {@code
* import com.google.inject.AbstractModule;
* import ratpack.guice.Guice;
* import ratpack.handling.Context;
* import ratpack.handling.Handler;
* import ratpack.test.embed.EmbeddedApp;
*
* import javax.inject.Inject;
* import javax.inject.Singleton;
*
* import static org.junit.Assert.*;
*
* public class Example {
*
* static class SomeService {
* private final String value;
*
* SomeService(String value) {
* this.value = value;
* }
*
* public String getValue() {
* return value;
* }
* }
*
* static class SomeOtherService {
* private final String value;
*
* SomeOtherService(String value) {
* this.value = value;
* }
*
* public String getValue() {
* return value;
* }
* }
*
* public static class ServiceModule extends AbstractModule {
* protected void configure() {
* bind(SomeService.class).toInstance(new SomeService("foo"));
* bind(SomeOtherService.class).toInstance(new SomeOtherService("bar"));
* bind(InjectedHandler.class);
* }
* }
*
* {@literal @}Singleton
* static class InjectedHandler implements Handler {
* private final SomeService service;
*
* {@literal @}Inject
* public InjectedHandler(SomeService service) {
* this.service = service;
* }
*
* public void handle(Context ctx) {
* ctx.render(service.getValue() + "-" + ctx.get(SomeOtherService.class).getValue());
* }
* }
*
* public static void main(String... args) throws Exception {
* EmbeddedApp.of(s -> s
* .registry(Guice.registry(b -> b.module(ServiceModule.class)))
* .handlers(chain -> {
* // The registry in a Guice backed chain can be used to retrieve objects that were bound,
* // or to create objects that are bound “just-in-time”.
* chain.get("some/path", InjectedHandler.class);
* })
* ).test(httpClient -> {
* assertEquals("foo-bar", httpClient.get("some/path").getBody().getText());
* });
* }
*
* }
* }
* Accessing Guice bound objects in Handlers
*
* There are two ways to use Guice bound objects in your handler implementations.
*
* Dependency Injected Handlers
*
* The {@code handler()} methods used to create a Guice backed application take an {@link Action} that operates on a {@link Chain} instance.
* This chain instance given to this action provides a Guice backed {@link Registry} via its {@link Chain#getRegistry()} method.
* This registry is able to retrieve objects that were explicitly bound (i.e. defined by a module), and bind objects “just in time”.
* This means that it can be used to construct dependency injected {@link Handler} implementations.
*
*
* Simply pass the class of the handler implementation to create a new dependency injected instance of to this method,
* then add it to the chain.
*
*
* See the code above for an example of this.
*
* Accessing dependencies via context registry lookup
*
* The {@link Context} object that is given to a handler's {@link Handler#handle(Context)}
* method is also a registry implementation. In a Guice backed app, Guice bound objects can be retrieved via the {@link Registry#get(Class)} method of
* the context. You can retrieve any bound object via its publicly bound type.
*
*
* However, this will not create “just-in-time” bindings. Only objects that were explicitly bound can be retrieved this way.
*
* Guice modules as Ratpack “plugins”.
*
* Add on Ratpack functionality is typically provided via Guice modules.
* For example, the Jackson integration for JSON serialisation
* is provided by the {@code ratpack-jackson} add-on which ships a Guice module.
* To use its functionality simply register the module it provides with the {@link BindingsSpec} used to bootstrap the application.
*
* Groovy Applications
*
* The Ratpack Groovy add-on provides application modes that automatically incorporate Guice (namely the “Ratpack Script” mode).
* The module registration process is simpler and more convenient in this mode, and there are additional options for obtaining
* Guice bound objects.
*
*
* See the Groovy add-on's documentation for more details.
*
*/
public abstract class Guice {
private Guice() {
}
/**
* Creates a Ratpack {@link Registry} backed by the given {@link Injector} that will NOT create objects via “just-in-time” binding.
*
* @param injector The injector to back the registry
* @return A registry that wraps the injector
*/
public static Registry registry(Injector injector) {
return Registry.backedBy(new InjectorRegistryBacking(injector));
}
public static Function registry(Action bindings) {
return baseRegistry -> registry(bindings, baseRegistry, newInjectorFactory(baseRegistry.get(ServerConfig.class)));
}
public static Function registry(Injector parentInjector, Action bindings) {
return baseRegistry -> registry(bindings, baseRegistry, childInjectorFactory(parentInjector));
}
private static Registry registry(Action bindings, Registry baseRegistry, Function injectorFactory) throws Exception {
Injector injector = buildInjector(baseRegistry, bindings, injectorFactory);
return registry(injector);
}
public static Function newInjectorFactory(final ServerConfig serverConfig) {
final Stage stage = serverConfig.isDevelopment() ? Stage.DEVELOPMENT : Stage.PRODUCTION;
return from -> from == null ? createInjector(stage) : createInjector(stage, from);
}
private static Function childInjectorFactory(final Injector parent) {
return from -> from == null ? parent.createChildInjector() : parent.createChildInjector(from);
}
static Injector buildInjector(Registry baseRegistry, Action bindingsAction, Function injectorFactory) throws Exception {
List> binderActions = Lists.newLinkedList();
List modules = Lists.newLinkedList();
ServerConfig serverConfig = baseRegistry.get(ServerConfig.class);
BindingsSpec bindings = new DefaultBindingsSpec(serverConfig, binderActions, modules);
modules.add(new RatpackBaseRegistryModule(baseRegistry));
modules.add(new ConfigModule(serverConfig.getRequiredConfig()));
try {
bindingsAction.execute(bindings);
} catch (Exception e) {
throw uncheck(e);
}
modules.add(new AdHocModule(binderActions));
Optional bindingsImposition = Impositions.current().get(BindingsImposition.class);
if (bindingsImposition.isPresent()) {
BindingsImposition imposition = bindingsImposition.get();
List> imposedBinderActions = Lists.newLinkedList();
List imposedModules = Lists.newLinkedList();
BindingsSpec imposedBindings = new DefaultBindingsSpec(serverConfig, imposedBinderActions, imposedModules);
imposition.getBindings().execute(imposedBindings);
imposedModules.add(new AdHocModule(imposedBinderActions));
Module imposedModule = imposedModules.stream().reduce((acc, next) -> Modules.override(acc).with(next)).get();
modules.add(imposedModule);
}
Module masterModule = modules.stream().reduce((acc, next) -> Modules.override(acc).with(next)).get();
return injectorFactory.apply(masterModule);
}
private static class AdHocModule implements Module {
private final List> binderActions;
public AdHocModule(List> binderActions) {
this.binderActions = binderActions;
}
@Override
public void configure(Binder binder) {
for (Action binderAction : binderActions) {
binderAction.toConsumer().accept(binder);
}
}
}
private static class ConfigModule implements Module {
private final Iterable> config;
public ConfigModule(Iterable> config) {
this.config = config;
}
@Override
public void configure(Binder binder) {
for (ConfigObject configObject : config) {
bind(binder, configObject);
}
}
private static void bind(Binder binder, ConfigObject configObject) {
binder.bind(GuiceUtil.toTypeLiteral(configObject.getTypeToken())).toInstance(configObject.getObject());
}
}
}