Add `HttpClientAutoConfiguration` and use it wherever possible

Add a new `HttpClientAutoConfiguration` class that provides
`ClientHttpRequestFactoryBuilder` and `ClientHttpRequestFactorySettings`
beans and new configuration properties.

The existing `RestTemplate`, `RestClient` and `WebServiceTemplate`
auto-configurations have been updated to make use of the new
HTTP client support.

Users may now set `spring.http.client` property to globally change
the `ClientHttpRequestFactory` used in their application.

Closes gh-36266

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/http/client/HttpClientAutoConfiguration.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2012-2024 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.http.client;
+
+import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.boot.autoconfigure.AutoConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.http.client.HttpClientProperties.Factory;
+import org.springframework.boot.autoconfigure.ssl.SslAutoConfiguration;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
+import org.springframework.boot.http.client.ClientHttpRequestFactorySettings;
+import org.springframework.boot.ssl.SslBundle;
+import org.springframework.boot.ssl.SslBundles;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Conditional;
+import org.springframework.http.client.ClientHttpRequestFactory;
+import org.springframework.util.StringUtils;
+
+/**
+ * {@link EnableAutoConfiguration Auto-configuration} for
+ * {@link ClientHttpRequestFactoryBuilder} and {@link ClientHttpRequestFactorySettings}.
+ *
+ * @author Phillip Webb
+ * @since 3.4.0
+ */
+@AutoConfiguration(after = SslAutoConfiguration.class)
+@ConditionalOnClass(ClientHttpRequestFactory.class)
+@Conditional(NotReactiveWebApplicationCondition.class)
+@EnableConfigurationProperties(HttpClientProperties.class)
+public class HttpClientAutoConfiguration {
+
+	@Bean
+	@ConditionalOnMissingBean
+	ClientHttpRequestFactoryBuilder<?> clientHttpRequestFactoryBuilder(HttpClientProperties httpClientProperties) {
+		Factory factory = httpClientProperties.getFactory();
+		return (factory != null) ? factory.builder() : ClientHttpRequestFactoryBuilder.detect();
+	}
+
+	@Bean
+	@ConditionalOnMissingBean
+	ClientHttpRequestFactorySettings clientHttpRequestFactorySettings(HttpClientProperties httpClientProperties,
+			ObjectProvider<SslBundles> sslBundles) {
+		SslBundle sslBundle = getSslBundle(httpClientProperties.getSsl(), sslBundles);
+		return new ClientHttpRequestFactorySettings(httpClientProperties.getConnectTimeout(),
+				httpClientProperties.getReadTimeout(), sslBundle);
+	}
+
+	private SslBundle getSslBundle(HttpClientProperties.Ssl properties, ObjectProvider<SslBundles> sslBundles) {
+		String name = properties.getBundle();
+		return (StringUtils.hasLength(name)) ? sslBundles.getObject().getBundle(name) : null;
+	}
+
+}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/http/client/HttpClientProperties.java

@@ -0,0 +1,145 @@
+/*
+ * Copyright 2012-2024 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.http.client;
+
+import java.time.Duration;
+import java.util.function.Supplier;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
+
+/**
+ * {@link ConfigurationProperties @ConfigurationProperties} for a Spring's blocking HTTP
+ * clients.
+ *
+ * @author Phillip Webb
+ * @since 3.4.0
+ */
+@ConfigurationProperties("spring.http.client")
+public class HttpClientProperties {
+
+	/**
+	 * Default factory used for a client HTTP request.
+	 */
+	private Factory factory;
+
+	/**
+	 * Default connect timeout for a client HTTP request.
+	 */
+	private Duration connectTimeout;
+
+	/**
+	 * Default read timeout for a client HTTP request.
+	 */
+	private Duration readTimeout;
+
+	/**
+	 * Default SSL configuration for a client HTTP request.
+	 */
+	private Ssl ssl = new Ssl();
+
+	public Factory getFactory() {
+		return this.factory;
+	}
+
+	public void setFactory(Factory factory) {
+		this.factory = factory;
+	}
+
+	public Duration getConnectTimeout() {
+		return this.connectTimeout;
+	}
+
+	public void setConnectTimeout(Duration connectTimeout) {
+		this.connectTimeout = connectTimeout;
+	}
+
+	public Duration getReadTimeout() {
+		return this.readTimeout;
+	}
+
+	public void setReadTimeout(Duration readTimeout) {
+		this.readTimeout = readTimeout;
+	}
+
+	public Ssl getSsl() {
+		return this.ssl;
+	}
+
+	/**
+	 * Supported factory types.
+	 */
+	public enum Factory {
+
+		/**
+		 * Apache HttpComponents HttpClient.
+		 */
+		HTTP_COMPONENTS(ClientHttpRequestFactoryBuilder::httpComponents),
+
+		/**
+		 * Jetty's HttpClient.
+		 */
+		JETTY(ClientHttpRequestFactoryBuilder::jetty),
+
+		/**
+		 * Reactor-Netty.
+		 */
+		REACTOR(ClientHttpRequestFactoryBuilder::reactor),
+
+		/**
+		 * Java's HttpClient.
+		 */
+		JDK(ClientHttpRequestFactoryBuilder::jdk),
+
+		/**
+		 * Standard JDK facilities.
+		 */
+		SIMPLE(ClientHttpRequestFactoryBuilder::simple);
+
+		private final Supplier<ClientHttpRequestFactoryBuilder<?>> builderSupplier;
+
+		Factory(Supplier<ClientHttpRequestFactoryBuilder<?>> builderSupplier) {
+			this.builderSupplier = builderSupplier;
+		}
+
+		ClientHttpRequestFactoryBuilder<?> builder() {
+			return this.builderSupplier.get();
+		}
+
+	}
+
+	/**
+	 * SSL configuration.
+	 */
+	public static class Ssl {
+
+		/**
+		 * SSL bundle to use.
+		 */
+		private String bundle;
+
+		public String getBundle() {
+			return this.bundle;
+		}
+
+		public void setBundle(String bundle) {
+			this.bundle = bundle;
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/http/client/NotReactiveWebApplicationCondition.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2012-2024 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.http.client;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
+import org.springframework.boot.autoconfigure.condition.NoneNestedConditions;
+import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
+
+/**
+ * {@link SpringBootCondition} that applies only when running in a non-reactive web
+ * application.
+ *
+ * @author Phillip Webb
+ */
+class NotReactiveWebApplicationCondition extends NoneNestedConditions {
+
+	NotReactiveWebApplicationCondition() {
+		super(ConfigurationPhase.PARSE_CONFIGURATION);
+	}
+
+	@ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.REACTIVE)
+	private static final class ReactiveWebApplication {
+
+	}
+
+}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/http/client/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-2024 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.
+ */
+
+/**
+ * Auto-configuration for client-side HTTP.
+ */
+package org.springframework.boot.autoconfigure.http.client;

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -18,10 +18,10 @@ package org.springframework.boot.autoconfigure.web.client;
 
 import java.util.function.Consumer;
 
+import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
+import org.springframework.boot.http.client.ClientHttpRequestFactorySettings;
 import org.springframework.boot.ssl.SslBundle;
 import org.springframework.boot.ssl.SslBundles;
-import org.springframework.boot.web.client.ClientHttpRequestFactories;
-import org.springframework.boot.web.client.ClientHttpRequestFactorySettings;
 import org.springframework.http.client.ClientHttpRequestFactory;
 import org.springframework.web.client.RestClient;
 
@@ -32,9 +32,13 @@ import org.springframework.web.client.RestClient;
  */
 class AutoConfiguredRestClientSsl implements RestClientSsl {
 
+	private final ClientHttpRequestFactoryBuilder<?> clientHttpRequestFactoryBuilder;
+
 	private final SslBundles sslBundles;
 
-	AutoConfiguredRestClientSsl(SslBundles sslBundles) {
+	AutoConfiguredRestClientSsl(ClientHttpRequestFactoryBuilder<?> clientHttpRequestFactoryBuilder,
+			SslBundles sslBundles) {
+		this.clientHttpRequestFactoryBuilder = clientHttpRequestFactoryBuilder;
 		this.sslBundles = sslBundles;
 	}
 
@@ -46,8 +50,8 @@ class AutoConfiguredRestClientSsl implements RestClientSsl {
 	@Override
 	public Consumer<RestClient.Builder> fromBundle(SslBundle bundle) {
 		return (builder) -> {
-			ClientHttpRequestFactorySettings settings = ClientHttpRequestFactorySettings.DEFAULTS.withSslBundle(bundle);
-			ClientHttpRequestFactory requestFactory = ClientHttpRequestFactories.get(settings);
+			ClientHttpRequestFactorySettings settings = ClientHttpRequestFactorySettings.ofSslBundle(bundle);
+			ClientHttpRequestFactory requestFactory = this.clientHttpRequestFactoryBuilder.build(settings);
 			builder.requestFactory(requestFactory);
 		};
 	}

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

@@ -24,10 +24,11 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
 import org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration;
+import org.springframework.boot.autoconfigure.http.client.HttpClientAutoConfiguration;
 import org.springframework.boot.autoconfigure.ssl.SslAutoConfiguration;
+import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
+import org.springframework.boot.http.client.ClientHttpRequestFactorySettings;
 import org.springframework.boot.ssl.SslBundles;
-import org.springframework.boot.web.client.ClientHttpRequestFactories;
-import org.springframework.boot.web.client.ClientHttpRequestFactorySettings;
 import org.springframework.boot.web.client.RestClientCustomizer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
@@ -48,7 +49,8 @@ import org.springframework.web.client.RestClient.Builder;
  * @author Moritz Halbritter
  * @since 3.2.0
  */
-@AutoConfiguration(after = { HttpMessageConvertersAutoConfiguration.class, SslAutoConfiguration.class })
+@AutoConfiguration(after = { HttpClientAutoConfiguration.class, HttpMessageConvertersAutoConfiguration.class,
+		SslAutoConfiguration.class })
 @ConditionalOnClass(RestClient.class)
 @Conditional(NotReactiveWebApplicationCondition.class)
 public class RestClientAutoConfiguration {
@@ -64,14 +66,21 @@ public class RestClientAutoConfiguration {
 	@Bean
 	@ConditionalOnMissingBean(RestClientSsl.class)
 	@ConditionalOnBean(SslBundles.class)
-	AutoConfiguredRestClientSsl restClientSsl(SslBundles sslBundles) {
-		return new AutoConfiguredRestClientSsl(sslBundles);
+	AutoConfiguredRestClientSsl restClientSsl(
+			ObjectProvider<ClientHttpRequestFactoryBuilder<?>> clientHttpRequestFactoryBuilder, SslBundles sslBundles) {
+		return new AutoConfiguredRestClientSsl(
+				clientHttpRequestFactoryBuilder.getIfAvailable(ClientHttpRequestFactoryBuilder::detect), sslBundles);
 	}
 
 	@Bean
 	@ConditionalOnMissingBean
-	RestClientBuilderConfigurer restClientBuilderConfigurer(ObjectProvider<RestClientCustomizer> customizerProvider) {
+	RestClientBuilderConfigurer restClientBuilderConfigurer(
+			ObjectProvider<ClientHttpRequestFactoryBuilder<?>> clientHttpRequestFactoryBuilder,
+			ObjectProvider<ClientHttpRequestFactorySettings> clientHttpRequestFactorySettings,
+			ObjectProvider<RestClientCustomizer> customizerProvider) {
 		RestClientBuilderConfigurer configurer = new RestClientBuilderConfigurer();
+		configurer.setRequestFactoryBuilder(clientHttpRequestFactoryBuilder.getIfAvailable());
+		configurer.setRequestFactorySettings(clientHttpRequestFactorySettings.getIfAvailable());
 		configurer.setRestClientCustomizers(customizerProvider.orderedStream().toList());
 		return configurer;
 	}
@@ -80,9 +89,7 @@ public class RestClientAutoConfiguration {
 	@Scope("prototype")
 	@ConditionalOnMissingBean
 	RestClient.Builder restClientBuilder(RestClientBuilderConfigurer restClientBuilderConfigurer) {
-		RestClient.Builder builder = RestClient.builder()
-			.requestFactory(ClientHttpRequestFactories.get(ClientHttpRequestFactorySettings.DEFAULTS));
-		return restClientBuilderConfigurer.configure(builder);
+		return restClientBuilderConfigurer.configure(RestClient.builder());
 	}
 
 }

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

@@ -18,6 +18,8 @@ package org.springframework.boot.autoconfigure.web.client;
 
 import java.util.List;
 
+import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
+import org.springframework.boot.http.client.ClientHttpRequestFactorySettings;
 import org.springframework.boot.web.client.RestClientCustomizer;
 import org.springframework.web.client.RestClient;
 import org.springframework.web.client.RestClient.Builder;
@@ -30,8 +32,20 @@ import org.springframework.web.client.RestClient.Builder;
  */
 public class RestClientBuilderConfigurer {
 
+	private ClientHttpRequestFactoryBuilder<?> requestFactoryBuilder;
+
+	private ClientHttpRequestFactorySettings requestFactorySettings;
+
 	private List<RestClientCustomizer> customizers;
 
+	void setRequestFactoryBuilder(ClientHttpRequestFactoryBuilder<?> requestFactoryBuilder) {
+		this.requestFactoryBuilder = requestFactoryBuilder;
+	}
+
+	void setRequestFactorySettings(ClientHttpRequestFactorySettings requestFactorySettings) {
+		this.requestFactorySettings = requestFactorySettings;
+	}
+
 	void setRestClientCustomizers(List<RestClientCustomizer> customizers) {
 		this.customizers = customizers;
 	}
@@ -43,6 +57,9 @@ public class RestClientBuilderConfigurer {
 	 * @return the configured builder
 	 */
 	public RestClient.Builder configure(RestClient.Builder builder) {
+		ClientHttpRequestFactoryBuilder<?> requestFactoryBuilder = (this.requestFactoryBuilder != null)
+				? this.requestFactoryBuilder : ClientHttpRequestFactoryBuilder.detect();
+		builder.requestFactory(requestFactoryBuilder.build(this.requestFactorySettings));
 		applyCustomizers(builder);
 		return builder;
 	}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -18,10 +18,9 @@ package org.springframework.boot.autoconfigure.web.client;
 
 import java.util.function.Consumer;
 
+import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
 import org.springframework.boot.ssl.NoSuchSslBundleException;
 import org.springframework.boot.ssl.SslBundle;
-import org.springframework.boot.web.client.ClientHttpRequestFactories;
-import org.springframework.boot.web.client.ClientHttpRequestFactorySettings;
 import org.springframework.http.client.ClientHttpRequestFactory;
 import org.springframework.web.client.RestClient;
 
@@ -38,8 +37,7 @@ import org.springframework.web.client.RestClient;
  * </pre> NOTE: Apply SSL configuration will replace any previously
  * {@link RestClient.Builder#requestFactory configured} {@link ClientHttpRequestFactory}.
  * If you need to configure {@link ClientHttpRequestFactory} with more than just SSL
- * consider using a {@link ClientHttpRequestFactorySettings} with
- * {@link ClientHttpRequestFactories}.
+ * consider using a {@link ClientHttpRequestFactoryBuilder}.
  *
  * @author Phillip Webb
  * @since 3.2.0

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

@@ -23,6 +23,9 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
 import org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration;
+import org.springframework.boot.autoconfigure.http.client.HttpClientAutoConfiguration;
+import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
+import org.springframework.boot.http.client.ClientHttpRequestFactorySettings;
 import org.springframework.boot.web.client.RestTemplateBuilder;
 import org.springframework.boot.web.client.RestTemplateCustomizer;
 import org.springframework.boot.web.client.RestTemplateRequestCustomizer;
@@ -32,13 +35,14 @@ import org.springframework.context.annotation.Lazy;
 import org.springframework.web.client.RestTemplate;
 
 /**
- * {@link EnableAutoConfiguration Auto-configuration} for {@link RestTemplate}.
+ * {@link EnableAutoConfiguration Auto-configuration} for {@link RestTemplate} (via
+ * {@link RestTemplateBuilder}).
  *
  * @author Stephane Nicoll
  * @author Phillip Webb
  * @since 1.4.0
  */
-@AutoConfiguration(after = HttpMessageConvertersAutoConfiguration.class)
+@AutoConfiguration(after = { HttpClientAutoConfiguration.class, HttpMessageConvertersAutoConfiguration.class })
 @ConditionalOnClass(RestTemplate.class)
 @Conditional(NotReactiveWebApplicationCondition.class)
 public class RestTemplateAutoConfiguration {
@@ -46,10 +50,14 @@ public class RestTemplateAutoConfiguration {
 	@Bean
 	@Lazy
 	public RestTemplateBuilderConfigurer restTemplateBuilderConfigurer(
+			ObjectProvider<ClientHttpRequestFactoryBuilder<?>> clientHttpRequestFactoryBuilder,
+			ObjectProvider<ClientHttpRequestFactorySettings> clientHttpRequestFactorySettings,
 			ObjectProvider<HttpMessageConverters> messageConverters,
 			ObjectProvider<RestTemplateCustomizer> restTemplateCustomizers,
 			ObjectProvider<RestTemplateRequestCustomizer<?>> restTemplateRequestCustomizers) {
 		RestTemplateBuilderConfigurer configurer = new RestTemplateBuilderConfigurer();
+		configurer.setRequestFactoryBuilder(clientHttpRequestFactoryBuilder.getIfAvailable());
+		configurer.setRequestFactorySettings(clientHttpRequestFactorySettings.getIfAvailable());
 		configurer.setHttpMessageConverters(messageConverters.getIfUnique());
 		configurer.setRestTemplateCustomizers(restTemplateCustomizers.orderedStream().toList());
 		configurer.setRestTemplateRequestCustomizers(restTemplateRequestCustomizers.orderedStream().toList());
@@ -60,8 +68,7 @@ public class RestTemplateAutoConfiguration {
 	@Lazy
 	@ConditionalOnMissingBean
 	public RestTemplateBuilder restTemplateBuilder(RestTemplateBuilderConfigurer restTemplateBuilderConfigurer) {
-		RestTemplateBuilder builder = new RestTemplateBuilder();
-		return restTemplateBuilderConfigurer.configure(builder);
+		return restTemplateBuilderConfigurer.configure(new RestTemplateBuilder());
 	}
 
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -21,6 +21,8 @@ import java.util.List;
 import java.util.function.BiFunction;
 
 import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
+import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
+import org.springframework.boot.http.client.ClientHttpRequestFactorySettings;
 import org.springframework.boot.web.client.RestTemplateBuilder;
 import org.springframework.boot.web.client.RestTemplateCustomizer;
 import org.springframework.boot.web.client.RestTemplateRequestCustomizer;
@@ -34,12 +36,24 @@ import org.springframework.util.ObjectUtils;
  */
 public final class RestTemplateBuilderConfigurer {
 
+	private ClientHttpRequestFactoryBuilder<?> requestFactoryBuilder;
+
+	private ClientHttpRequestFactorySettings requestFactorySettings;
+
 	private HttpMessageConverters httpMessageConverters;
 
 	private List<RestTemplateCustomizer> restTemplateCustomizers;
 
 	private List<RestTemplateRequestCustomizer<?>> restTemplateRequestCustomizers;
 
+	void setRequestFactoryBuilder(ClientHttpRequestFactoryBuilder<?> requestFactoryBuilder) {
+		this.requestFactoryBuilder = requestFactoryBuilder;
+	}
+
+	void setRequestFactorySettings(ClientHttpRequestFactorySettings requestFactorySettings) {
+		this.requestFactorySettings = requestFactorySettings;
+	}
+
 	void setHttpMessageConverters(HttpMessageConverters httpMessageConverters) {
 		this.httpMessageConverters = httpMessageConverters;
 	}
@@ -59,6 +73,12 @@ public final class RestTemplateBuilderConfigurer {
 	 * @return the configured builder
 	 */
 	public RestTemplateBuilder configure(RestTemplateBuilder builder) {
+		if (this.requestFactoryBuilder != null) {
+			builder = builder.requestFactoryBuilder(this.requestFactoryBuilder);
+		}
+		if (this.requestFactorySettings != null) {
+			builder = builder.requestFactorySettings(this.requestFactorySettings);
+		}
 		if (this.httpMessageConverters != null) {
 			builder = builder.messageConverters(this.httpMessageConverters.getConverters());
 		}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/webservices/client/WebServiceTemplateAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -23,6 +23,10 @@ import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.http.client.HttpClientAutoConfiguration;
+import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
+import org.springframework.boot.http.client.ClientHttpRequestFactorySettings;
+import org.springframework.boot.webservices.client.WebServiceMessageSenderFactory;
 import org.springframework.boot.webservices.client.WebServiceTemplateBuilder;
 import org.springframework.boot.webservices.client.WebServiceTemplateCustomizer;
 import org.springframework.context.annotation.Bean;
@@ -36,20 +40,35 @@ import org.springframework.ws.client.core.WebServiceTemplate;
  * @author Dmytro Nosan
  * @since 2.1.0
  */
-@AutoConfiguration
+@AutoConfiguration(after = HttpClientAutoConfiguration.class)
 @ConditionalOnClass({ WebServiceTemplate.class, Unmarshaller.class, Marshaller.class })
 public class WebServiceTemplateAutoConfiguration {
 
+	@Bean
+	@ConditionalOnMissingBean
+	public WebServiceMessageSenderFactory webServiceHttpMessageSenderFactory(
+			ObjectProvider<ClientHttpRequestFactoryBuilder<?>> clientHttpRequestFactoryBuilder,
+			ObjectProvider<ClientHttpRequestFactorySettings> clientHttpRequestFactorySettings) {
+		return WebServiceMessageSenderFactory.http(
+				clientHttpRequestFactoryBuilder.getIfAvailable(ClientHttpRequestFactoryBuilder::detect),
+				clientHttpRequestFactorySettings.getIfAvailable());
+	}
+
 	@Bean
 	@ConditionalOnMissingBean
 	public WebServiceTemplateBuilder webServiceTemplateBuilder(
+			ObjectProvider<WebServiceMessageSenderFactory> httpWebServiceMessageSenderBuilder,
 			ObjectProvider<WebServiceTemplateCustomizer> webServiceTemplateCustomizers) {
-		WebServiceTemplateBuilder builder = new WebServiceTemplateBuilder();
+		WebServiceTemplateBuilder templateBuilder = new WebServiceTemplateBuilder();
+		WebServiceMessageSenderFactory httpMessageSenderFactory = httpWebServiceMessageSenderBuilder.getIfAvailable();
+		if (httpMessageSenderFactory != null) {
+			templateBuilder = templateBuilder.httpMessageSenderFactory(httpMessageSenderFactory);
+		}
 		List<WebServiceTemplateCustomizer> customizers = webServiceTemplateCustomizers.orderedStream().toList();
 		if (!customizers.isEmpty()) {
-			builder = builder.customizers(customizers);
+			templateBuilder = templateBuilder.customizers(customizers);
 		}
-		return builder;
+		return templateBuilder;
 	}
 
 }

spring-boot-project/spring-boot-autoconfigure/src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

@@ -62,6 +62,7 @@ org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration
 org.springframework.boot.autoconfigure.hazelcast.HazelcastAutoConfiguration
 org.springframework.boot.autoconfigure.hazelcast.HazelcastJpaDependencyAutoConfiguration
 org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration
+org.springframework.boot.autoconfigure.http.client.HttpClientAutoConfiguration
 org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration
 org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration
 org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/http/client/HttpClientAutoConfigurationTests.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2012-2024 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.http.client;
+
+import java.time.Duration;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.autoconfigure.ssl.SslAutoConfiguration;
+import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
+import org.springframework.boot.http.client.ClientHttpRequestFactorySettings;
+import org.springframework.boot.http.client.SimpleClientHttpRequestFactoryBuilder;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.boot.test.context.runner.ReactiveWebApplicationContextRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link HttpClientAutoConfiguration}.
+ *
+ * @author Phillip Webb
+ */
+class HttpClientAutoConfigurationTests {
+
+	private static final AutoConfigurations autoConfigurations = AutoConfigurations
+		.of(HttpClientAutoConfiguration.class, SslAutoConfiguration.class);
+
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+		.withConfiguration(autoConfigurations);
+
+	@Test
+	void configuresDetectedClientHttpRequestFactoryBuilder() {
+		this.contextRunner.run((context) -> assertThat(context).hasSingleBean(ClientHttpRequestFactoryBuilder.class));
+	}
+
+	@Test
+	void configuresDefinedClientHttpRequestFactoryBuilder() {
+		this.contextRunner.withPropertyValues("spring.http.client.factory=simple")
+			.run((context) -> assertThat(context.getBean(ClientHttpRequestFactoryBuilder.class))
+				.isInstanceOf(SimpleClientHttpRequestFactoryBuilder.class));
+	}
+
+	@Test
+	void configuresClientHttpRequestFactorySettings() {
+		this.contextRunner.withPropertyValues(sslPropertyValues().toArray(String[]::new))
+			.withPropertyValues("spring.http.client.connect-timeout=10s", "spring.http.client.read-timeout=20s",
+					"spring.http.client.ssl.bundle=test")
+			.run((context) -> {
+				ClientHttpRequestFactorySettings settings = context.getBean(ClientHttpRequestFactorySettings.class);
+				assertThat(settings.connectTimeout()).isEqualTo(Duration.ofSeconds(10));
+				assertThat(settings.readTimeout()).isEqualTo(Duration.ofSeconds(20));
+				assertThat(settings.sslBundle().getKey().getAlias()).isEqualTo("alias1");
+			});
+	}
+
+	private List<String> sslPropertyValues() {
+		List<String> propertyValues = new ArrayList<>();
+		String location = "classpath:org/springframework/boot/autoconfigure/ssl/";
+		propertyValues.add("spring.ssl.bundle.pem.test.key.alias=alias1");
+		propertyValues.add("spring.ssl.bundle.pem.test.truststore.type=PKCS12");
+		propertyValues.add("spring.ssl.bundle.pem.test.truststore.certificate=" + location + "rsa-cert.pem");
+		propertyValues.add("spring.ssl.bundle.pem.test.truststore.private-key=" + location + "rsa-key.pem");
+		return propertyValues;
+	}
+
+	@Test
+	void whenReactiveWebApplicationBeansAreNotConfigured() {
+		new ReactiveWebApplicationContextRunner().withConfiguration(autoConfigurations)
+			.run((context) -> assertThat(context).doesNotHaveBean(ClientHttpRequestFactoryBuilder.class)
+				.doesNotHaveBean(ClientHttpRequestFactorySettings.class));
+	}
+
+}

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/http/client/HttpClientPropertiesTests.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2012-2024 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.http.client;
+
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.autoconfigure.http.client.HttpClientProperties.Factory;
+import org.springframework.boot.http.client.HttpComponentsClientHttpRequestFactoryBuilder;
+import org.springframework.boot.http.client.JdkClientHttpRequestFactoryBuilder;
+import org.springframework.boot.http.client.JettyClientHttpRequestFactoryBuilder;
+import org.springframework.boot.http.client.ReactorClientHttpRequestFactoryBuilder;
+import org.springframework.boot.http.client.SimpleClientHttpRequestFactoryBuilder;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link HttpClientProperties}.
+ *
+ * @author Phillip Webb
+ */
+class HttpClientPropertiesTests {
+
+	@Nested
+	class FactoryTests {
+
+		@Test
+		void httpComponentsBuilder() {
+			assertThat(Factory.HTTP_COMPONENTS.builder())
+				.isInstanceOf(HttpComponentsClientHttpRequestFactoryBuilder.class);
+		}
+
+		@Test
+		void jettyBuilder() {
+			assertThat(Factory.JETTY.builder()).isInstanceOf(JettyClientHttpRequestFactoryBuilder.class);
+		}
+
+		@Test
+		void reactorBuilder() {
+			assertThat(Factory.REACTOR.builder()).isInstanceOf(ReactorClientHttpRequestFactoryBuilder.class);
+		}
+
+		@Test
+		void jdkBuilder() {
+			assertThat(Factory.JDK.builder()).isInstanceOf(JdkClientHttpRequestFactoryBuilder.class);
+		}
+
+		@Test
+		void simpleBuilder() {
+			assertThat(Factory.SIMPLE.builder()).isInstanceOf(SimpleClientHttpRequestFactoryBuilder.class);
+		}
+
+	}
+
+}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -23,12 +23,14 @@ import org.junit.jupiter.api.Test;
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
 import org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration;
+import org.springframework.boot.autoconfigure.http.client.HttpClientAutoConfiguration;
 import org.springframework.boot.ssl.SslBundles;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.boot.web.client.RestClientCustomizer;
 import org.springframework.boot.web.codec.CodecCustomizer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.http.client.SimpleClientHttpRequestFactory;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.test.util.ReflectionTestUtils;
@@ -49,7 +51,7 @@ import static org.mockito.Mockito.mock;
 class RestClientAutoConfigurationTests {
 
 	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
-		.withConfiguration(AutoConfigurations.of(RestClientAutoConfiguration.class));
+		.withConfiguration(AutoConfigurations.of(RestClientAutoConfiguration.class, HttpClientAutoConfiguration.class));
 
 	@Test
 	void shouldSupplyBeans() {
@@ -156,6 +158,19 @@ class RestClientAutoConfigurationTests {
 			});
 	}
 
+	@Test
+	void whenHasFactoryProperty() {
+		this.contextRunner.withConfiguration(AutoConfigurations.of(HttpMessageConvertersAutoConfiguration.class))
+			.withUserConfiguration(RestClientConfig.class)
+			.withPropertyValues("spring.http.client.factory=simple")
+			.run((context) -> {
+				assertThat(context).hasSingleBean(RestClient.class);
+				RestClient restClient = context.getBean(RestClient.class);
+				assertThat(restClient).extracting("clientRequestFactory")
+					.isInstanceOf(SimpleClientHttpRequestFactory.class);
+			});
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class CodecConfiguration {
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -25,6 +25,7 @@ import org.springframework.beans.factory.support.BeanDefinitionOverrideException
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
 import org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration;
+import org.springframework.boot.autoconfigure.http.client.HttpClientAutoConfiguration;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.boot.test.context.runner.ReactiveWebApplicationContextRunner;
 import org.springframework.boot.test.context.runner.WebApplicationContextRunner;
@@ -36,6 +37,7 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.client.ClientHttpRequestFactory;
 import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
+import org.springframework.http.client.SimpleClientHttpRequestFactory;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.mock.http.client.MockClientHttpRequest;
@@ -56,8 +58,8 @@ import static org.mockito.Mockito.mock;
  */
 class RestTemplateAutoConfigurationTests {
 
-	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
-		.withConfiguration(AutoConfigurations.of(RestTemplateAutoConfiguration.class));
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner().withConfiguration(
+			AutoConfigurations.of(RestTemplateAutoConfiguration.class, HttpClientAutoConfiguration.class));
 
 	@Test
 	void restTemplateBuilderConfigurerShouldBeLazilyDefined() {
@@ -191,6 +193,18 @@ class RestTemplateAutoConfigurationTests {
 				.doesNotHaveBean(RestTemplateBuilderConfigurer.class));
 	}
 
+	@Test
+	void whenHasFactoryProperty() {
+		this.contextRunner.withConfiguration(AutoConfigurations.of(HttpMessageConvertersAutoConfiguration.class))
+			.withUserConfiguration(RestTemplateConfig.class)
+			.withPropertyValues("spring.http.client.factory=simple")
+			.run((context) -> {
+				assertThat(context).hasSingleBean(RestTemplate.class);
+				RestTemplate restTemplate = context.getBean(RestTemplate.class);
+				assertThat(restTemplate.getRequestFactory()).isInstanceOf(SimpleClientHttpRequestFactory.class);
+			});
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class RestTemplateConfig {
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/webservices/client/WebServiceTemplateAutoConfigurationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -21,6 +21,8 @@ import java.util.function.Consumer;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration;
+import org.springframework.boot.autoconfigure.http.client.HttpClientAutoConfiguration;
 import org.springframework.boot.test.context.assertj.AssertableApplicationContext;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.boot.test.context.runner.ContextConsumer;
@@ -28,6 +30,7 @@ import org.springframework.boot.webservices.client.WebServiceTemplateBuilder;
 import org.springframework.boot.webservices.client.WebServiceTemplateCustomizer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.http.client.SimpleClientHttpRequestFactory;
 import org.springframework.oxm.Marshaller;
 import org.springframework.oxm.Unmarshaller;
 import org.springframework.oxm.jaxb.Jaxb2Marshaller;
@@ -45,8 +48,8 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class WebServiceTemplateAutoConfigurationTests {
 
-	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
-		.withConfiguration(AutoConfigurations.of(WebServiceTemplateAutoConfiguration.class));
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner().withConfiguration(
+			AutoConfigurations.of(WebServiceTemplateAutoConfiguration.class, HttpClientAutoConfiguration.class));
 
 	@Test
 	void autoConfiguredBuilderShouldNotHaveMarshallerAndUnmarshaller() {
@@ -93,6 +96,19 @@ class WebServiceTemplateAutoConfigurationTests {
 			.run((context) -> assertThat(context).hasNotFailed());
 	}
 
+	@Test
+	void whenHasFactoryProperty() {
+		this.contextRunner.withConfiguration(AutoConfigurations.of(HttpMessageConvertersAutoConfiguration.class))
+			.withPropertyValues("spring.http.client.factory=simple")
+			.run(assertWebServiceTemplateBuilder((builder) -> {
+				WebServiceTemplate webServiceTemplate = builder.build();
+				assertThat(webServiceTemplate.getMessageSenders()).hasSize(1);
+				ClientHttpRequestMessageSender messageSender = (ClientHttpRequestMessageSender) webServiceTemplate
+					.getMessageSenders()[0];
+				assertThat(messageSender.getRequestFactory()).isInstanceOf(SimpleClientHttpRequestFactory.class);
+			}));
+	}
+
 	private ContextConsumer<AssertableApplicationContext> assertWebServiceTemplateBuilder(
 			Consumer<WebServiceTemplateBuilder> builder) {
 		return (context) -> {

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-actuator-ui/src/test/java/smoketest/actuator/ui/SampleActuatorUiApplicationPortTests.java

@@ -36,7 +36,8 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Dave Syer
  */
-@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT, properties = { "management.server.port:0" })
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT,
+		properties = { "management.server.port:0", "spring.http.client.factory=simple" })
 class SampleActuatorUiApplicationPortTests {
 
 	@LocalServerPort

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-actuator-ui/src/test/java/smoketest/actuator/ui/SampleActuatorUiApplicationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -39,7 +39,8 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Dave Syer
  */
-@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT, properties = { "server.error.include-message=always" })
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT,
+		properties = { "server.error.include-message=always", "spring.http.client.factory=simple" })
 class SampleActuatorUiApplicationTests {
 
 	@Autowired
@@ -50,7 +51,7 @@ class SampleActuatorUiApplicationTests {
 		HttpHeaders headers = new HttpHeaders();
 		headers.setAccept(Arrays.asList(MediaType.TEXT_HTML));
 		ResponseEntity<String> entity = this.restTemplate.withBasicAuth("user", getPassword())
-			.exchange("/", HttpMethod.GET, new HttpEntity<Void>(headers), String.class);
+			.exchange("/", HttpMethod.GET, new HttpEntity<>(headers), String.class);
 		assertThat(entity.getStatusCode()).isEqualTo(HttpStatus.OK);
 		assertThat(entity.getBody()).contains("<title>Hello");
 	}
@@ -74,7 +75,7 @@ class SampleActuatorUiApplicationTests {
 		HttpHeaders headers = new HttpHeaders();
 		headers.setAccept(Arrays.asList(MediaType.TEXT_HTML));
 		ResponseEntity<String> entity = this.restTemplate.withBasicAuth("user", getPassword())
-			.exchange("/error", HttpMethod.GET, new HttpEntity<Void>(headers), String.class);
+			.exchange("/error", HttpMethod.GET, new HttpEntity<>(headers), String.class);
 		assertThat(entity.getStatusCode()).isEqualTo(HttpStatus.INTERNAL_SERVER_ERROR);
 		assertThat(entity.getBody()).contains("<html>")
 			.contains("<body>")

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-session-jdbc/src/test/java/smoketest/session/SampleSessionJdbcApplicationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -48,7 +48,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Madhura Bhave
  */
 @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
-		properties = "server.servlet.session.timeout:2")
+		properties = { "server.servlet.session.timeout:2", "spring.http.client.factory=simple" })
 class SampleSessionJdbcApplicationTests {
 
 	@Autowired

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-web-method-security/src/test/java/smoketest/security/method/SampleMethodSecurityApplicationTests.java

@@ -43,7 +43,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Dave Syer
  * @author Scott Frederick
  */
-@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT, properties = "spring.http.client.factory=simple")
 class SampleMethodSecurityApplicationTests {
 
 	@LocalServerPort