LoadBalancerWebClientBuilderBeanPostProcessor.java

/*
 * Copyright 2012-present 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
 *
 *      https://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.cloud.client.loadbalancer.reactive;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.client.loadbalancer.SimpleObjectProvider;
import org.springframework.context.ApplicationContext;
import org.springframework.web.reactive.function.client.WebClient;

/**
 * A {@link BeanPostProcessor} that applies
 * {@link DeferringLoadBalancerExchangeFilterFunction} filter to all
 * {@link WebClient.Builder} instances annotated with {@link LoadBalanced}.
 *
 * @author Olga Maciaszek-Sharma
 * @since 2.2.0
 */
@SuppressWarnings({ "removal", "rawtypes" })
public class LoadBalancerWebClientBuilderBeanPostProcessor implements BeanPostProcessor {

	private final ObjectProvider<DeferringLoadBalancerExchangeFilterFunction> exchangeFilterFunctionObjectProvider;

	private final ApplicationContext context;

	/**
	 * @deprecated in favour of
	 * {@link LoadBalancerWebClientBuilderBeanPostProcessor#LoadBalancerWebClientBuilderBeanPostProcessor(ObjectProvider, ApplicationContext)}
	 */
	@Deprecated(forRemoval = true)
	public LoadBalancerWebClientBuilderBeanPostProcessor(
			DeferringLoadBalancerExchangeFilterFunction exchangeFilterFunction, ApplicationContext context) {
		this.exchangeFilterFunctionObjectProvider = new SimpleObjectProvider<>(exchangeFilterFunction);
		this.context = context;
	}

	public LoadBalancerWebClientBuilderBeanPostProcessor(
			ObjectProvider<DeferringLoadBalancerExchangeFilterFunction> exchangeFilterFunction,
			ApplicationContext context) {
		this.exchangeFilterFunctionObjectProvider = exchangeFilterFunction;
		this.context = context;
	}

	@Override
	public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
		if (bean instanceof WebClient.Builder) {
			if (context.findAnnotationOnBean(beanName, LoadBalanced.class) == null) {
				return bean;
			}
			DeferringLoadBalancerExchangeFilterFunction exchangeFilterFunction = exchangeFilterFunctionObjectProvider
				.getIfAvailable();
			if (exchangeFilterFunction == null) {
				throw new IllegalStateException("LoadBalancerExchangeFilterFunction not found");
			}
			((WebClient.Builder) bean).filter(exchangeFilterFunctionObjectProvider.getIfAvailable());
		}
		return bean;
	}

}