com.google.inject.Inject Maven / Gradle / Ivy
/*
* Copyright (C) 2006 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.
*/
package com.google.inject;
import static java.lang.annotation.ElementType.CONSTRUCTOR;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
/**
* Annotates members of your implementation class (constructors, methods and fields) into which the
* {@link Injector} should inject values. The Injector fulfills injection requests for:
*
*
* - Every instance it constructs. The class being constructed must have exactly one of its
* constructors marked with {@code @Inject} or must have a constructor taking no parameters. The
* Injector then proceeds to perform field and method injections.
*
- Pre-constructed instances passed to {@link Injector#injectMembers}, {@link
* com.google.inject.binder.LinkedBindingBuilder#toInstance(Object)} and {@link
* com.google.inject.binder.LinkedBindingBuilder#toProvider(javax.inject.Provider)}. In this
* case all constructors are, of course, ignored.
*
- Static fields and methods of classes which any {@link Module} has specifically requested
* static injection for, using {@link Binder#requestStaticInjection}.
*
*
* In all cases, a member can be injected regardless of its Java access specifier (private, default,
* protected, public).
*
* @author [email protected] (Bob Lee)
*/
@Target({METHOD, CONSTRUCTOR, FIELD})
@Retention(RUNTIME)
@Documented
public @interface Inject {
/**
* If true, and the appropriate binding is not found, the Injector will skip injection of this
* method or field rather than produce an error. When applied to a field, any default value
* already assigned to the field will remain (guice will not actively null out the field). When
* applied to a method, the method will only be invoked if bindings for all parameters are
* found. When applied to a constructor, an error will result upon Injector creation.
*/
boolean optional() default false;
}