Add support for headers in `@HttpExchange`

On the client side, supports `name=value` pairs. Placeholders in values
are resolved by the `embeddedValueResolver`.
On the server side, additionally supports `name` and `!name` syntax.

Closes gh-33309

framework-docs/modules/ROOT/pages/integration/rest-clients.adoc

@@ -938,7 +938,8 @@ method parameters:
 | `@RequestHeader`
 | Add a request header or multiple headers. The argument may be a `Map<String, ?>` or
   `MultiValueMap<String, ?>` with multiple headers, a `Collection<?>` of values, or an
-  individual value. Type conversion is supported for non-String values.
+  individual value. Type conversion is supported for non-String values. This overrides
+  the annotation's `headers` attribute.
 
 | `@PathVariable`
 | Add a variable for expand a placeholder in the request URL. The argument may be a

framework-docs/modules/ROOT/pages/web/webflux/controller/ann-requestmapping.adoc

@@ -606,3 +606,8 @@ subset of the method parameters that `@RequestMapping` does. Notably, it exclude
 server-side specific parameter types. For details, see the list for
 xref:integration/rest-clients.adoc#rest-http-interface-method-parameters[@HttpExchange] and
 xref:web/webflux/controller/ann-methods/arguments.adoc[@RequestMapping].
+
+`@HttpExchange` also supports a `headers()` parameter which accepts `"name=value"`-like
+pairs like in `@RequestMapping(headers={})` on the client side. On the server side,
+this extends to the full syntax that
+xref:#webflux-ann-requestmapping-params-and-headers[`@RequestMapping`] supports.

framework-docs/modules/ROOT/pages/web/webmvc/mvc-controller/ann-requestmapping.adoc

@@ -652,3 +652,8 @@ subset of the method parameters that `@RequestMapping` does. Notably, it exclude
 server-side specific parameter types. For details, see the list for
 xref:integration/rest-clients.adoc#rest-http-interface-method-parameters[@HttpExchange] and
 xref:web/webmvc/mvc-controller/ann-methods/arguments.adoc[@RequestMapping].
+
+`@HttpExchange` also supports a `headers()` parameter which accepts `"name=value"`-like
+pairs like in `@RequestMapping(headers={})` on the client side. On the server side,
+this extends to the full syntax that
+xref:#mvc-ann-requestmapping-params-and-headers[`@RequestMapping`] supports.

spring-web/src/main/java/org/springframework/web/service/annotation/DeleteExchange.java

@@ -60,4 +60,10 @@ public @interface DeleteExchange {
 	@AliasFor(annotation = HttpExchange.class)
 	String[] accept() default {};
 
+	/**
+	 * Alias for {@link HttpExchange#headers()}.
+	 */
+	@AliasFor(annotation = HttpExchange.class)
+	String[] headers() default {};
+
 }

spring-web/src/main/java/org/springframework/web/service/annotation/HttpExchange.java

@@ -173,4 +173,16 @@ public @interface HttpExchange {
 	 */
 	String[] accept() default {};
 
+	/**
+	 * The additional headers to use, as an array of {@code name=value} pairs.
+	 * <p>Multiple comma-separated values are accepted, and placeholders are
+	 * supported in these values. However, Accept and Content-Type headers are
+	 * ignored: see {@link #accept()} and {@link #contentType()}.
+	 * <p>Supported at the type level as well as at the method level, in which
+	 * case the method-level values override type-level values.
+	 * <p>By default, this is empty.
+	 * @since 6.2
+	 */
+	String[] headers() default {};
+
 }

spring-web/src/main/java/org/springframework/web/service/annotation/PatchExchange.java

@@ -60,4 +60,10 @@ public @interface PatchExchange {
 	@AliasFor(annotation = HttpExchange.class)
 	String[] accept() default {};
 
+	/**
+	 * Alias for {@link HttpExchange#headers()}.
+	 */
+	@AliasFor(annotation = HttpExchange.class)
+	String[] headers() default {};
+
 }

spring-web/src/main/java/org/springframework/web/service/annotation/PostExchange.java

@@ -60,4 +60,10 @@ public @interface PostExchange {
 	@AliasFor(annotation = HttpExchange.class)
 	String[] accept() default {};
 
+	/**
+	 * Alias for {@link HttpExchange#headers()}.
+	 */
+	@AliasFor(annotation = HttpExchange.class)
+	String[] headers() default {};
+
 }

spring-web/src/main/java/org/springframework/web/service/annotation/PutExchange.java

@@ -60,4 +60,10 @@ public @interface PutExchange {
 	@AliasFor(annotation = HttpExchange.class)
 	String[] accept() default {};
 
+	/**
+	 * Alias for {@link HttpExchange#headers()}.
+	 */
+	@AliasFor(annotation = HttpExchange.class)
+	String[] headers() default {};
+
 }

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

@@ -19,8 +19,10 @@ package org.springframework.web.service.invoker;
 import java.lang.reflect.AnnotatedElement;
 import java.lang.reflect.Method;
 import java.time.Duration;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
+import java.util.Set;
 import java.util.function.Function;
 import java.util.function.Supplier;
 
@@ -46,6 +48,8 @@ import org.springframework.http.ResponseEntity;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.util.StringValueResolver;
@@ -156,6 +160,7 @@ final class HttpServiceMethod {
 	private record HttpRequestValuesInitializer(
 			@Nullable HttpMethod httpMethod, @Nullable String url,
 			@Nullable MediaType contentType, @Nullable List<MediaType> acceptMediaTypes,
+			@Nullable MultiValueMap<String, String> otherHeaders,
 			Supplier<HttpRequestValues.Builder> requestValuesSupplier) {
 
 		public HttpRequestValues.Builder initializeRequestValuesBuilder() {
@@ -172,6 +177,16 @@ final class HttpServiceMethod {
 			if (this.acceptMediaTypes != null) {
 				requestValues.setAccept(this.acceptMediaTypes);
 			}
+			if (this.otherHeaders != null) {
+				this.otherHeaders.forEach((name, values) -> {
+					if (values.size() == 1) {
+						requestValues.addHeader(name, values.get(0));
+					}
+					else {
+						requestValues.addHeader(name, values.toArray(new String[0]));
+					}
+				});
+			}
 			return requestValues;
 		}
 
@@ -202,9 +217,10 @@ final class HttpServiceMethod {
 			String url = initUrl(typeAnnotation, methodAnnotation, embeddedValueResolver);
 			MediaType contentType = initContentType(typeAnnotation, methodAnnotation);
 			List<MediaType> acceptableMediaTypes = initAccept(typeAnnotation, methodAnnotation);
-
-			return new HttpRequestValuesInitializer(
-					httpMethod, url, contentType, acceptableMediaTypes, requestValuesSupplier);
+			MultiValueMap<String, String> headers = initHeaders(typeAnnotation, methodAnnotation,
+					embeddedValueResolver);
+			return new HttpRequestValuesInitializer(httpMethod, url, contentType,
+					acceptableMediaTypes, headers, requestValuesSupplier);
 		}
 
 		@Nullable
@@ -280,6 +296,50 @@ final class HttpServiceMethod {
 			return null;
 		}
 
+		private static MultiValueMap<String, String> parseHeaders(String[] headersArray,
+				@Nullable StringValueResolver embeddedValueResolver) {
+			MultiValueMap<String, String> headers = new LinkedMultiValueMap<>();
+			for (String h: headersArray) {
+				String[] headerPair = StringUtils.split(h, "=");
+				if (headerPair != null) {
+					String headerName = headerPair[0].trim();
+					List<String> headerValues = new ArrayList<>();
+					Set<String> parsedValues = StringUtils.commaDelimitedListToSet(headerPair[1]);
+					for (String headerValue : parsedValues) {
+						if (embeddedValueResolver != null) {
+							headerValue = embeddedValueResolver.resolveStringValue(headerValue);
+						}
+						if (headerValue != null) {
+							headerValue = headerValue.trim();
+							headerValues.add(headerValue);
+						}
+					}
+					if (!headerValues.isEmpty()) {
+						headers.addAll(headerName, headerValues);
+					}
+				}
+			}
+			return headers;
+		}
+
+		@Nullable
+		private static MultiValueMap<String, String> initHeaders(@Nullable HttpExchange typeAnnotation, HttpExchange methodAnnotation,
+				@Nullable StringValueResolver embeddedValueResolver) {
+			MultiValueMap<String, String> methodLevelHeaders = parseHeaders(methodAnnotation.headers(),
+					embeddedValueResolver);
+			if (!ObjectUtils.isEmpty(methodLevelHeaders)) {
+				return methodLevelHeaders;
+			}
+
+			MultiValueMap<String, String> typeLevelHeaders = (typeAnnotation != null ?
+					parseHeaders(typeAnnotation.headers(), embeddedValueResolver) : null);
+			if (!ObjectUtils.isEmpty(typeLevelHeaders)) {
+				return typeLevelHeaders;
+			}
+
+			return null;
+		}
+
 		private static List<AnnotationDescriptor> getAnnotationDescriptors(AnnotatedElement element) {
 			return MergedAnnotations.from(element, SearchStrategy.TYPE_HIERARCHY, RepeatableContainers.none())
 					.stream(HttpExchange.class)

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

@@ -48,6 +48,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 import static org.springframework.http.MediaType.APPLICATION_CBOR_VALUE;
 import static org.springframework.http.MediaType.APPLICATION_JSON_VALUE;
+import static org.springframework.http.MediaType.APPLICATION_NDJSON_VALUE;
 
 /**
  * Tests for {@link HttpServiceMethod} with
@@ -184,6 +185,15 @@ class HttpServiceMethodTests {
 		assertThat(requestValues.getUriTemplate()).isEqualTo("/url");
 		assertThat(requestValues.getHeaders().getContentType()).isEqualTo(MediaType.APPLICATION_JSON);
 		assertThat(requestValues.getHeaders().getAccept()).containsOnly(MediaType.APPLICATION_JSON);
+
+		service.performGetWithHeaders();
+
+		requestValues = this.client.getRequestValues();
+		assertThat(requestValues.getHttpMethod()).isEqualTo(HttpMethod.GET);
+		assertThat(requestValues.getUriTemplate()).isEmpty();
+		assertThat(requestValues.getHeaders().getContentType()).isEqualTo(MediaType.APPLICATION_JSON);
+		assertThat(requestValues.getHeaders().getAccept()).isEmpty();
+		assertThat(requestValues.getHeaders().get("CustomHeader")).containsExactly("a", "b", "c");
 	}
 
 	@Test
@@ -338,6 +348,10 @@ class HttpServiceMethodTests {
 		@PostExchange(url = "/url", contentType = APPLICATION_JSON_VALUE, accept = APPLICATION_JSON_VALUE)
 		void performPost();
 
+		@HttpExchange(contentType = APPLICATION_JSON_VALUE, headers = {"CustomHeader=a,b, c",
+				"Content-Type=" + APPLICATION_NDJSON_VALUE}, method = "GET")
+		void performGetWithHeaders();
+
 	}
 
 

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/RequestMappingHandlerMapping.java

@@ -296,7 +296,8 @@ public class RequestMappingHandlerMapping extends RequestMappingInfoHandlerMappi
 				.paths(resolveEmbeddedValuesInPatterns(toStringArray(httpExchange.value())))
 				.methods(toMethodArray(httpExchange.method()))
 				.consumes(toStringArray(httpExchange.contentType()))
-				.produces(httpExchange.accept());
+				.produces(httpExchange.accept())
+				.headers(httpExchange.headers());
 
 		if (customCondition != null) {
 			builder.customCondition(customCondition);

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/RequestMappingHandlerMappingTests.java

@@ -303,6 +303,26 @@ class RequestMappingHandlerMappingTests {
 				.containsOnly(MediaType.valueOf("text/plain;charset=UTF-8"));
 	}
 
+	@SuppressWarnings("DataFlowIssue")
+	@Test
+	void httpExchangeWithCustomHeaders() {
+		this.handlerMapping.afterPropertiesSet();
+
+		RequestMappingHandlerMapping mapping = new RequestMappingHandlerMapping();
+		mapping.setApplicationContext(new StaticWebApplicationContext());
+		mapping.afterPropertiesSet();
+
+		Class<HttpExchangeController> clazz = HttpExchangeController.class;
+		Method method = ReflectionUtils.findMethod(clazz, "customHeadersExchange");
+		RequestMappingInfo mappingInfo = mapping.getMappingForMethod(method, clazz);
+
+		assertThat(mappingInfo.getMethodsCondition().getMethods()).containsOnly(RequestMethod.GET);
+		assertThat(mappingInfo.getParamsCondition().getExpressions()).isEmpty();
+
+		assertThat(mappingInfo.getHeadersCondition().getExpressions().stream().map(Object::toString))
+				.containsExactly("h1=hv1", "!h2");
+	}
+
 	private RequestMappingInfo assertComposedAnnotationMapping(RequestMethod requestMethod) {
 		String methodName = requestMethod.name().toLowerCase();
 		String path = "/" + methodName;
@@ -409,6 +429,12 @@ class RequestMappingHandlerMappingTests {
 
 		@PostExchange(url = "/custom", contentType = "application/json", accept = "text/plain;charset=UTF-8")
 		public void customValuesExchange(){}
+
+		@HttpExchange(method="GET", url = "/headers",
+				headers = {"h1=hv1", "!h2", "Accept=application/ignored"})
+		public String customHeadersExchange() {
+			return "info";
+		}
 	}
 
 	@HttpExchange("/exchange")

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerMapping.java

@@ -449,7 +449,8 @@ public class RequestMappingHandlerMapping extends RequestMappingInfoHandlerMappi
 				.paths(resolveEmbeddedValuesInPatterns(toStringArray(httpExchange.value())))
 				.methods(toMethodArray(httpExchange.method()))
 				.consumes(toStringArray(httpExchange.contentType()))
-				.produces(httpExchange.accept());
+				.produces(httpExchange.accept())
+				.headers(httpExchange.headers());
 
 		if (customCondition != null) {
 			builder.customCondition(customCondition);

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerMappingTests.java

@@ -431,6 +431,26 @@ class RequestMappingHandlerMappingTests {
 				.containsOnly(MediaType.valueOf("text/plain;charset=UTF-8"));
 	}
 
+	@SuppressWarnings("DataFlowIssue")
+	@Test
+	void httpExchangeWithCustomHeaders() throws Exception {
+		RequestMappingHandlerMapping mapping = createMapping();
+
+		RequestMappingInfo mappingInfo = mapping.getMappingForMethod(
+				HttpExchangeController.class.getMethod("customHeadersExchange"),
+				HttpExchangeController.class);
+
+		assertThat(mappingInfo.getPathPatternsCondition().getPatterns())
+				.extracting(PathPattern::toString)
+				.containsOnly("/exchange/headers");
+
+		assertThat(mappingInfo.getMethodsCondition().getMethods()).containsOnly(RequestMethod.GET);
+		assertThat(mappingInfo.getParamsCondition().getExpressions()).isEmpty();
+
+		assertThat(mappingInfo.getHeadersCondition().getExpressions().stream().map(Object::toString))
+				.containsExactly("h1=hv1", "!h2");
+	}
+
 	private static RequestMappingHandlerMapping createMapping() {
 		RequestMappingHandlerMapping mapping = new RequestMappingHandlerMapping();
 		mapping.setApplicationContext(new StaticWebApplicationContext());
@@ -543,6 +563,12 @@ class RequestMappingHandlerMappingTests {
 
 		@PostExchange(url = "/custom", contentType = "application/json", accept = "text/plain;charset=UTF-8")
 		public void customValuesExchange(){}
+
+		@HttpExchange(method="GET", url = "/headers",
+				headers = {"h1=hv1", "!h2", "Accept=application/ignored"})
+		public String customHeadersExchange() {
+			return "info";
+		}
 	}