org.springframework.core.ReactiveAdapter Maven / Gradle / Ivy
/*
* Copyright 2002-2017 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.core;
import java.util.function.Function;
import org.reactivestreams.Publisher;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* Adapt a Reactive Streams {@link Publisher} to and from an async/reactive type
* such as {@code CompletableFuture}, an RxJava {@code Observable}, etc.
*
* Use the {@link ReactiveAdapterRegistry} to register reactive types and
* obtain adapters from.
*
* @author Rossen Stoyanchev
* @since 5.0
*/
public class ReactiveAdapter {
private final ReactiveTypeDescriptor descriptor;
private final Function> toPublisherFunction;
private final Function, Object> fromPublisherFunction;
/**
* Constructor for an adapter with functions to convert the target reactive
* or async type to and from a Reactive Streams Publisher.
* @param descriptor the reactive type descriptor
* @param toPublisherFunction adapter to a Publisher
* @param fromPublisherFunction adapter from a Publisher
*/
public ReactiveAdapter(ReactiveTypeDescriptor descriptor,
Function> toPublisherFunction,
Function, Object> fromPublisherFunction) {
Assert.notNull(descriptor, "'descriptor' is required");
Assert.notNull(toPublisherFunction, "'toPublisherFunction' is required");
Assert.notNull(fromPublisherFunction, "'fromPublisherFunction' is required");
this.descriptor = descriptor;
this.toPublisherFunction = toPublisherFunction;
this.fromPublisherFunction = fromPublisherFunction;
}
/**
* Return the descriptor of the reactive type for the adapter.
*/
public ReactiveTypeDescriptor getDescriptor() {
return this.descriptor;
}
/**
* A shortcut for {@code getDescriptor().getReactiveType()}.
*/
public Class getReactiveType() {
return getDescriptor().getReactiveType();
}
/**
* A shortcut for {@code getDescriptor().isMultiValue()}.
*/
public boolean isMultiValue() {
return getDescriptor().isMultiValue();
}
/**
* A shortcut for {@code getDescriptor().supportsEmpty()}.
*/
public boolean supportsEmpty() {
return getDescriptor().supportsEmpty();
}
/**
* A shortcut for {@code getDescriptor().isNoValue()}.
*/
public boolean isNoValue() {
return getDescriptor().isNoValue();
}
/**
* Adapt the given instance to a Reactive Streams Publisher.
* @param source the source object to adapt from
* @return the Publisher representing the adaptation
*/
@SuppressWarnings("unchecked")
public Publisher toPublisher(@Nullable Object source) {
if (source == null) {
source = getDescriptor().getEmptyValue();
}
return (Publisher) this.toPublisherFunction.apply(source);
}
/**
* Adapt from the given Reactive Streams Publisher.
* @param publisher the publisher to adapt from
* @return the reactive type instance representing the adapted publisher
*/
public Object fromPublisher(Publisher publisher) {
return this.fromPublisherFunction.apply(publisher);
}
}