Implement RestClientBuilderConfigurer

Closes gh-36265

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/client/RestClientAutoConfiguration.java

@@ -36,11 +36,12 @@ import org.springframework.web.client.RestClient;
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for {@link RestClient}.
  * <p>
- * This will produce a {@link org.springframework.web.client.RestClient.Builder
- * RestClient.Builder} bean with the {@code prototype} scope, meaning each injection point
- * will receive a newly cloned instance of the builder.
+ * This will produce a {@link RestClient.Builder RestClient.Builder} bean with the
+ * {@code prototype} scope, meaning each injection point will receive a newly cloned
+ * instance of the builder.
  *
  * @author Arjen Poutsma
+ * @author Moritz Halbritter
  * @since 3.2.0
  */
 @AutoConfiguration(after = HttpMessageConvertersAutoConfiguration.class)
@@ -51,19 +52,26 @@ public class RestClientAutoConfiguration {
 	@Bean
 	@ConditionalOnMissingBean
 	@Order(Ordered.LOWEST_PRECEDENCE)
-	public HttpMessageConvertersRestClientCustomizer httpMessageConvertersRestClientCustomizer(
+	HttpMessageConvertersRestClientCustomizer httpMessageConvertersRestClientCustomizer(
 			ObjectProvider<HttpMessageConverters> messageConverters) {
 		return new HttpMessageConvertersRestClientCustomizer(messageConverters.getIfUnique());
 	}
 
+	@Bean
+	@ConditionalOnMissingBean
+	RestClientBuilderConfigurer restClientBuilderConfigurer(ObjectProvider<RestClientCustomizer> customizerProvider) {
+		RestClientBuilderConfigurer configurer = new RestClientBuilderConfigurer();
+		configurer.setRestClientCustomizers(customizerProvider.orderedStream().toList());
+		return configurer;
+	}
+
 	@Bean
 	@Scope("prototype")
 	@ConditionalOnMissingBean
-	public RestClient.Builder restClientBuilder(ObjectProvider<RestClientCustomizer> customizerProvider) {
+	RestClient.Builder restClientBuilder(RestClientBuilderConfigurer restClientBuilderConfigurer) {
 		RestClient.Builder builder = RestClient.builder()
 			.requestFactory(ClientHttpRequestFactories.get(ClientHttpRequestFactorySettings.DEFAULTS));
-		customizerProvider.orderedStream().forEach((customizer) -> customizer.customize(builder));
-		return builder;
+		return restClientBuilderConfigurer.configure(builder);
 	}
 
 }

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/client/RestClientBuilderConfigurer.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2012-2023 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.boot.autoconfigure.web.client;
+
+import java.util.List;
+
+import org.springframework.boot.web.client.RestClientCustomizer;
+import org.springframework.web.client.RestClient;
+import org.springframework.web.client.RestClient.Builder;
+
+/**
+ * Configure {@link RestClient.Builder} with sensible defaults.
+ *
+ * @author Moritz Halbritter
+ * @since 3.2.0
+ */
+public class RestClientBuilderConfigurer {
+
+	private List<RestClientCustomizer> customizers;
+
+	void setRestClientCustomizers(List<RestClientCustomizer> customizers) {
+		this.customizers = customizers;
+	}
+
+	/**
+	 * Configure the specified {@link RestClient.Builder}. The builder can be further
+	 * tuned and default settings can be overridden.
+	 * @param builder the {@link RestClient.Builder} instance to configure
+	 * @return the configured builder
+	 */
+	public RestClient.Builder configure(RestClient.Builder builder) {
+		applyCustomizers(builder);
+		return builder;
+	}
+
+	private void applyCustomizers(Builder builder) {
+		if (this.customizers != null) {
+			for (RestClientCustomizer customizer : this.customizers) {
+				customizer.customize(builder);
+			}
+		}
+	}
+
+}

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/client/RestClientAutoConfigurationTests.java

@@ -32,6 +32,7 @@ import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.test.util.ReflectionTestUtils;
 import org.springframework.web.client.RestClient;
+import org.springframework.web.client.RestClient.Builder;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.ArgumentMatchers.any;
@@ -42,12 +43,22 @@ import static org.mockito.Mockito.mock;
  * Tests for {@link RestClientAutoConfiguration}
  *
  * @author Arjen Poutsma
+ * @author Moritz Halbritter
  */
 class RestClientAutoConfigurationTests {
 
 	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
 		.withConfiguration(AutoConfigurations.of(RestClientAutoConfiguration.class));
 
+	@Test
+	void shouldSupplyBeans() {
+		this.contextRunner.run((context) -> {
+			assertThat(context).hasSingleBean(HttpMessageConvertersRestClientCustomizer.class);
+			assertThat(context).hasSingleBean(RestClientBuilderConfigurer.class);
+			assertThat(context).hasSingleBean(RestClient.Builder.class);
+		});
+	}
+
 	@Test
 	void shouldCreateBuilder() {
 		this.contextRunner.run((context) -> {
@@ -57,6 +68,17 @@ class RestClientAutoConfigurationTests {
 		});
 	}
 
+	@Test
+	void configurerShouldCallCustomizers() {
+		this.contextRunner.withUserConfiguration(RestClientCustomizerConfig.class).run((context) -> {
+			RestClientBuilderConfigurer configurer = context.getBean(RestClientBuilderConfigurer.class);
+			RestClientCustomizer customizer = context.getBean("restClientCustomizer", RestClientCustomizer.class);
+			Builder builder = RestClient.builder();
+			configurer.configure(builder);
+			then(customizer).should().customize(builder);
+		});
+	}
+
 	@Test
 	void restClientShouldApplyCustomizers() {
 		this.contextRunner.withUserConfiguration(RestClientCustomizerConfig.class).run((context) -> {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/client/RestClientBuilderConfigurerTests.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2012-2023 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.boot.autoconfigure.web.client;
+
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.web.client.RestClientCustomizer;
+import org.springframework.web.client.RestClient;
+
+import static org.assertj.core.api.Assertions.assertThatCode;
+import static org.mockito.BDDMockito.then;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link RestClientBuilderConfigurer}.
+ *
+ * @author Moritz Halbritter
+ */
+class RestClientBuilderConfigurerTests {
+
+	@Test
+	void shouldApplyCustomizers() {
+		RestClientBuilderConfigurer configurer = new RestClientBuilderConfigurer();
+		RestClientCustomizer customizer = mock(RestClientCustomizer.class);
+		configurer.setRestClientCustomizers(List.of(customizer));
+		RestClient.Builder builder = RestClient.builder();
+		configurer.configure(builder);
+		then(customizer).should().customize(builder);
+	}
+
+	@Test
+	void shouldSupportNullAsCustomizers() {
+		RestClientBuilderConfigurer configurer = new RestClientBuilderConfigurer();
+		configurer.setRestClientCustomizers(null);
+		assertThatCode(() -> configurer.configure(RestClient.builder())).doesNotThrowAnyException();
+	}
+
+}