/* * SPDX-License-Identifier: Apache-2.0 * * The OpenSearch Contributors require contributions made to * this file be licensed under the Apache-2.0 license or a * compatible open source license. */ /* * Copyright (C) 2007 Google Inc. * * 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. */ /* * Modifications Copyright OpenSearch Contributors. See * GitHub history for details. */ package org.opensearch.common.inject; import org.opensearch.common.inject.binder.AnnotatedBindingBuilder; import org.opensearch.common.inject.binder.AnnotatedConstantBindingBuilder; import org.opensearch.common.inject.binder.LinkedBindingBuilder; import org.opensearch.common.inject.matcher.Matcher; import org.opensearch.common.inject.spi.Message; import org.opensearch.common.inject.spi.TypeConverter; import org.opensearch.common.inject.spi.TypeListener; import java.lang.annotation.Annotation; /** * Collects configuration information (primarily bindings) which will be * used to create an {@link Injector}. Guice provides this object to your * application's {@link Module} implementors so they may each contribute * their own bindings and other registrations. *
* Guice uses an embedded domain-specific language, or EDSL, to help you * create bindings simply and readably. This approach is great for overall * usability, but it does come with a small cost: it is difficult to * learn how to use the Binding EDSL by reading * method-level javadocs. Instead, you should consult the series of * examples below. To save space, these examples omit the opening * {@code binder}, just as you will if your module extends * {@link AbstractModule}. *
* bind(ServiceImpl.class);* * This statement does essentially nothing; it "binds the {@code ServiceImpl} * class to itself" and does not change Guice's default behavior. You may still * want to use this if you prefer your {@link Module} class to serve as an * explicit manifest for the services it provides. Also, in rare cases, * Guice may be unable to validate a binding at injector creation time unless it * is given explicitly. * *
* bind(Service.class).to(ServiceImpl.class);* * Specifies that a request for a {@code Service} instance with no binding * annotations should be treated as if it were a request for a * {@code ServiceImpl} instance. This overrides the function of any * {@link ImplementedBy @ImplementedBy} or {@link ProvidedBy @ProvidedBy} * annotations found on {@code Service}, since Guice will have already * "moved on" to {@code ServiceImpl} before it reaches the point when it starts * looking for these annotations. * *
* bind(Service.class).toProvider(ServiceProvider.class);* * In this example, {@code ServiceProvider} must extend or implement * {@code Provider
The {@link Provider} you use here does not have to be a "factory"; that * is, a provider which always creates each instance it provides. * However, this is generally a good practice to follow. You can then use * Guice's concept of {@link Scope scopes} to guide when creation should happen * -- "letting Guice work for you". * *
* bind(Service.class).annotatedWith(Red.class).to(ServiceImpl.class);* * Like the previous example, but only applies to injection requests that use * the binding annotation {@code @Red}. If your module also includes bindings * for particular values of the {@code @Red} annotation (see below), * then this binding will serve as a "catch-all" for any values of {@code @Red} * that have no exact match in the bindings. * *
* bind(ServiceImpl.class).in(Singleton.class); * // or, alternatively * bind(ServiceImpl.class).in(Scopes.SINGLETON);* * Either of these statements places the {@code ServiceImpl} class into * singleton scope. Guice will create only one instance of {@code ServiceImpl} * and will reuse it for all injection requests of this type. Note that it is * still possible to bind another instance of {@code ServiceImpl} if the second * binding is qualified by an annotation as in the previous example. Guice is * not overly concerned with preventing you from creating multiple * instances of your "singletons", only with enabling your application to * share only one instance if that's all you tell Guice you need. * *
Note: a scope specified in this way overrides any scope that * was specified with an annotation on the {@code ServiceImpl} class. * *
Besides {@link Singleton}/{@link Scopes#SINGLETON}, there are * servlet-specific scopes available in * {@code com.google.inject.servlet.ServletScopes}, and your Modules can * contribute their own custom scopes for use here as well. * *
* bind(new TypeLiteral<PaymentService<CreditCard>>() {}) * .to(CreditCardPaymentService.class);* * This admittedly odd construct is the way to bind a parameterized type. It * tells Guice how to honor an injection request for an element of type * {@code PaymentService
* bind(Service.class).toInstance(new ServiceImpl()); * // or, alternatively * bind(Service.class).toInstance(SomeLegacyRegistry.getService());* * In this example, your module itself, not Guice, takes responsibility * for obtaining a {@code ServiceImpl} instance, then asks Guice to always use * this single instance to fulfill all {@code Service} injection requests. When * the {@link Injector} is created, it will automatically perform field * and method injection for this instance, but any injectable constructor on * {@code ServiceImpl} is simply ignored. Note that using this approach results * in "eager loading" behavior that you can't control. * *
* bindConstant().annotatedWith(ServerHost.class).to(args[0]);* * Sets up a constant binding. Constant injections must always be annotated. * When a constant binding's value is a string, it is eligible for conversion to * all primitive types, to {@link Enum#valueOf all enums}, and to * {@link Class#forName class literals}. Conversions for other types can be * configured using {@link #convertToTypes(Matcher, TypeConverter) * convertToTypes()}. * *
* {@literal @}Color("red") Color red; // A member variable (field) * . . . * red = MyModule.class.getDeclaredField("red").getAnnotation(Color.class); * bind(Service.class).annotatedWith(red).to(RedService.class);* * If your binding annotation has parameters you can apply different bindings to * different specific values of your annotation. Getting your hands on the * right instance of the annotation is a bit of a pain -- one approach, shown * above, is to apply a prototype annotation to a field in your module class, so * that you can read this annotation instance and give it to Guice. * *
* bind(Service.class) * .annotatedWith(Names.named("blue")) * .to(BlueService.class);* * Differentiating by names is a common enough use case that we provided a * standard annotation, {@link org.opensearch.common.inject.name.Named @Named}. Because of * Guice's library support, binding by name is quite easier than in the * arbitrary binding annotation case we just saw. However, remember that these * names will live in a single flat namespace with all the other names used in * your application. * *
The above list of examples is far from exhaustive. If you can think of * how the concepts of one example might coexist with the concepts from another, * you can most likely weave the two together. If the two concepts make no * sense with each other, you most likely won't be able to do it. In a few * cases Guice will let something bogus slip by, and will then inform you of * the problems at runtime, as soon as you try to create your Injector. * *
The other methods of Binder such as {@link #bindScope},
* {@link #install}, {@link #requestStaticInjection},
* {@link #addError} and {@link #currentStage} are not part of the Binding EDSL;
* you can learn how to use these in the usual way, from the method
* documentation.
*
* @author crazybob@google.com (Bob Lee)
* @author jessewilson@google.com (Jesse Wilson)
* @author kevinb@google.com (Kevin Bourrillion)
*
* @opensearch.internal
*/
public interface Binder {
/**
* Binds a scope to an annotation.
*/
void bindScope(Class extends Annotation> annotationType, Scope scope);
/**
* See the EDSL examples at {@link Binder}.
*/