Allow customization of the ProxyFactory in HttpServiceProxyFactory used to create HTTP service proxies

spring-web/src/main/java/org/springframework/web/service/invoker/HttpServiceProxyFactory.java

@@ -63,16 +63,19 @@ public final class HttpServiceProxyFactory {
 
 	private final @Nullable StringValueResolver embeddedValueResolver;
 
+	private final List<ProxyFactoryCustomizer> proxyCustomizers;
 
 	private HttpServiceProxyFactory(
 			HttpExchangeAdapter exchangeAdapter, List<HttpServiceArgumentResolver> argumentResolvers,
 			List<HttpRequestValues.Processor> requestValuesProcessor,
-			@Nullable StringValueResolver embeddedValueResolver) {
+			@Nullable StringValueResolver embeddedValueResolver,
+			List<ProxyFactoryCustomizer> proxyCustomizers) {
 
 		this.exchangeAdapter = exchangeAdapter;
 		this.argumentResolvers = argumentResolvers;
 		this.requestValuesProcessor = new CompositeHttpRequestValuesProcessor(requestValuesProcessor);
 		this.embeddedValueResolver = embeddedValueResolver;
+		this.proxyCustomizers = proxyCustomizers;
 	}
 
 
@@ -84,7 +87,6 @@ private HttpServiceProxyFactory(
 	 * @return the created proxy
 	 */
 	public <S> S createClient(Class<S> serviceType) {
-
 		List<HttpServiceMethod> httpServiceMethods =
 				MethodIntrospector.selectMethods(serviceType, this::isExchangeMethod).stream()
 						.map(method -> createHttpServiceMethod(serviceType, method))
@@ -97,6 +99,9 @@ public <S> S createClient(Class<S> serviceType) {
 	private <S> S getProxy(Class<S> serviceType, List<HttpServiceMethod> httpServiceMethods) {
 		MethodInterceptor interceptor = new HttpServiceMethodInterceptor(httpServiceMethods);
 		ProxyFactory factory = new ProxyFactory(serviceType, interceptor);
+		for (var customizer : this.proxyCustomizers) {
+			customizer.customize(factory, serviceType);
+		}
 		return (S) factory.getProxy(serviceType.getClassLoader());
 	}
 
@@ -147,6 +152,8 @@ public static final class Builder {
 
 		private @Nullable StringValueResolver embeddedValueResolver;
 
+		private final List<ProxyFactoryCustomizer> proxyCustomizers = new ArrayList<>();
+
 		private Builder() {
 		}
 
@@ -216,6 +223,19 @@ public Builder embeddedValueResolver(StringValueResolver embeddedValueResolver)
 			return this;
 		}
 
+		/**
+		 * Register an {@link ProxyFactoryCustomizer} that can
+		 * manipulating the {@link ProxyFactory} before creating proxy.
+		 *
+		 * @param customizer the customizer to add
+		 * @return this same builder instance
+		 * @since 7.1
+		 */
+		public Builder proxyCustomizer(ProxyFactoryCustomizer customizer) {
+			this.proxyCustomizers.add(customizer);
+			return this;
+		}
+
 		/**
 		 * Build the {@link HttpServiceProxyFactory} instance.
 		 */
@@ -225,7 +245,7 @@ public HttpServiceProxyFactory build() {
 
 			return new HttpServiceProxyFactory(
 					adapterToUse, initArgumentResolvers(), this.requestValuesProcessors,
-					this.embeddedValueResolver);
+					this.embeddedValueResolver, this.proxyCustomizers);
 		}
 
 		@SuppressWarnings({"DataFlowIssue", "NullAway"})
@@ -313,4 +333,18 @@ public void process(
 		}
 	}
 
+	/**
+	 * Callback interface used during HttpService proxy creation. Allows manipulating the {@link ProxyFactory} creating the
+	 * HttpService.
+	 *
+	 * @author Dung Dang Minh
+	 */
+	public interface ProxyFactoryCustomizer {
+		/**
+		 * Manipulates the {@link ProxyFactory}, e.g. add further interceptors to it.
+		 *
+		 * @param factory will never be {@literal null}.
+		 */
+		void customize(ProxyFactory factory, Class<?> serviceType);
+	}
 }

spring-web/src/test/java/org/springframework/web/service/invoker/HttpServiceProxyFactoryTests.java

@@ -16,9 +16,9 @@
 
 package org.springframework.web.service.invoker;
 
+import org.aopalliance.intercept.MethodInterceptor;
 import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
-
 import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.web.service.annotation.GetExchange;
 
@@ -44,6 +44,18 @@ void httpExchangeAdapterDecorator() {
 	}
 
 
+	@Test
+	void proxyFactoryCustomizer() {
+		var mi = (MethodInterceptor) invocation -> "intercepted";
+		var factory = HttpServiceProxyFactory.builderFor(mock(HttpExchangeAdapter.class))
+				.proxyCustomizer((fact, serviceType) -> {
+					fact.addAdvice(0, mi);
+				}).build();
+
+		var service = factory.createClient(Service.class);
+		assertThat(service.execute()).isEqualTo("intercepted");
+	}
+
 	private interface Service {
 
 		@GetExchange