org.springframework.beans.factory.ObjectProvider Maven / Gradle / Ivy
/*
* Copyright 2002-2018 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 org.springframework.beans.factory;
import java.util.Iterator;
import java.util.function.Consumer;
import java.util.function.Supplier;
import java.util.stream.Stream;
import org.springframework.beans.BeansException;
import org.springframework.lang.Nullable;
/**
* A variant of {@link ObjectFactory} designed specifically for injection points,
* allowing for programmatic optionality and lenient not-unique handling.
*
* As of 5.1, this interface extends {@link Iterable} and provides {@link Stream}
* support. It can be therefore be used in {@code for} loops, provides {@link #forEach}
* iteration and allows for collection-style {@link #stream} access.
*
* @author Juergen Hoeller
* @since 4.3
* @param the object type
* @see BeanFactory#getBeanProvider
* @see org.springframework.beans.factory.annotation.Autowired
*/
public interface ObjectProvider extends ObjectFactory, Iterable {
/**
* Return an instance (possibly shared or independent) of the object
* managed by this factory.
* Allows for specifying explicit construction arguments, along the
* lines of {@link BeanFactory#getBean(String, Object...)}.
* @param args arguments to use when creating a corresponding instance
* @return an instance of the bean
* @throws BeansException in case of creation errors
* @see #getObject()
*/
T getObject(Object... args) throws BeansException;
/**
* Return an instance (possibly shared or independent) of the object
* managed by this factory.
* @return an instance of the bean, or {@code null} if not available
* @throws BeansException in case of creation errors
* @see #getObject()
*/
@Nullable
T getIfAvailable() throws BeansException;
/**
* Return an instance (possibly shared or independent) of the object
* managed by this factory.
* @param defaultSupplier a callback for supplying a default object
* if none is present in the factory
* @return an instance of the bean, or the supplied default object
* if no such bean is available
* @throws BeansException in case of creation errors
* @since 5.0
* @see #getIfAvailable()
*/
default T getIfAvailable(Supplier defaultSupplier) throws BeansException {
T dependency = getIfAvailable();
return (dependency != null ? dependency : defaultSupplier.get());
}
/**
* Consume an instance (possibly shared or independent) of the object
* managed by this factory, if available.
* @param dependencyConsumer a callback for processing the target object
* if available (not called otherwise)
* @throws BeansException in case of creation errors
* @since 5.0
* @see #getIfAvailable()
*/
default void ifAvailable(Consumer dependencyConsumer) throws BeansException {
T dependency = getIfAvailable();
if (dependency != null) {
dependencyConsumer.accept(dependency);
}
}
/**
* Return an instance (possibly shared or independent) of the object
* managed by this factory.
* @return an instance of the bean, or {@code null} if not available or
* not unique (i.e. multiple candidates found with none marked as primary)
* @throws BeansException in case of creation errors
* @see #getObject()
*/
@Nullable
T getIfUnique() throws BeansException;
/**
* Return an instance (possibly shared or independent) of the object
* managed by this factory.
* @param defaultSupplier a callback for supplying a default object
* if no unique candidate is present in the factory
* @return an instance of the bean, or the supplied default object
* if no such bean is available or if it is not unique in the factory
* (i.e. multiple candidates found with none marked as primary)
* @throws BeansException in case of creation errors
* @since 5.0
* @see #getIfUnique()
*/
default T getIfUnique(Supplier defaultSupplier) throws BeansException {
T dependency = getIfUnique();
return (dependency != null ? dependency : defaultSupplier.get());
}
/**
* Consume an instance (possibly shared or independent) of the object
* managed by this factory, if unique.
* @param dependencyConsumer a callback for processing the target object
* if unique (not called otherwise)
* @throws BeansException in case of creation errors
* @since 5.0
* @see #getIfAvailable()
*/
default void ifUnique(Consumer dependencyConsumer) throws BeansException {
T dependency = getIfUnique();
if (dependency != null) {
dependencyConsumer.accept(dependency);
}
}
/**
* Return an {@link Iterator} over all matching object instances,
* without specific ordering guarantees (but typically in registration order).
* @since 5.1
* @see #stream()
*/
@Override
default Iterator iterator() {
return stream().iterator();
}
/**
* Return a sequential {@link Stream} over all matching object instances,
* without specific ordering guarantees (but typically in registration order).
* @since 5.1
* @see #iterator()
* @see #orderedStream()
*/
default Stream stream() {
throw new UnsupportedOperationException("Multi element access not supported");
}
/**
* Return a sequential {@link Stream} over all matching object instances,
* pre-ordered according to the factory's common order comparator.
* In a standard Spring application context, this will be ordered
* according to {@link org.springframework.core.Ordered} conventions,
* and in case of annotation-based configuration also considering the
* {@link org.springframework.core.annotation.Order} annotation,
* analogous to multi-element injection points of list/array type.
* @since 5.1
* @see #stream()
* @see org.springframework.core.OrderComparator
*/
default Stream orderedStream() {
throw new UnsupportedOperationException("Ordered element access not supported");
}
}