Empty body checks in ConsumesRequestCondition

Normally consumes matches the "Content-Type" header but what should be done if
there is no content? This commit adds checks for method parameters with
@RequestBody(required=false) and if "false" then also match requests with no content.

Closes gh-22010

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/condition/ConsumesRequestCondition.java

@@ -24,6 +24,7 @@ import java.util.List;
 import java.util.Set;
 import javax.servlet.http.HttpServletRequest;
 
+import org.springframework.http.HttpHeaders;
 import org.springframework.http.InvalidMediaTypeException;
 import org.springframework.http.MediaType;
 import org.springframework.lang.Nullable;
@@ -49,8 +50,11 @@ public final class ConsumesRequestCondition extends AbstractRequestCondition<Con
 
 	private static final ConsumesRequestCondition EMPTY_CONDITION = new ConsumesRequestCondition();
 
+
 	private final List<ConsumeMediaTypeExpression> expressions;
 
+	private boolean bodyRequired = true;
+
 
 	/**
 	 * Creates a new instance from 0 or more "consumes" expressions.
@@ -141,6 +145,29 @@ public final class ConsumesRequestCondition extends AbstractRequestCondition<Con
 		return " || ";
 	}
 
+	/**
+	 * Whether this condition should expect requests to have a body.
+	 * <p>By default this is set to {@code true} in which case it is assumed a
+	 * request body is required and this condition matches to the "Content-Type"
+	 * header or falls back on "Content-Type: application/octet-stream".
+	 * <p>If set to {@code false}, and the request does not have a body, then this
+	 * condition matches automatically, i.e. without checking expressions.
+	 * @param bodyRequired whether requests are expected to have a body
+	 * @since 5.2
+	 */
+	public void setBodyRequired(boolean bodyRequired) {
+		this.bodyRequired = bodyRequired;
+	}
+
+	/**
+	 * Return the setting for {@link #setBodyRequired(boolean)}.
+	 * @since 5.2
+	 */
+	public boolean isBodyRequired() {
+		return this.bodyRequired;
+	}
+
+
 	/**
 	 * Returns the "other" instance if it has any expressions; returns "this"
 	 * instance otherwise. Practically that means a method-level "consumes"
@@ -170,14 +197,17 @@ public final class ConsumesRequestCondition extends AbstractRequestCondition<Con
 		if (isEmpty()) {
 			return this;
 		}
+		if (!hasBody(request) && !this.bodyRequired) {
+			return EMPTY_CONDITION;
+		}
 
 		// Common media types are cached at the level of MimeTypeUtils
 
 		MediaType contentType;
 		try {
-			contentType = (StringUtils.hasLength(request.getContentType()) ?
+			contentType = StringUtils.hasLength(request.getContentType()) ?
 					MediaType.parseMediaType(request.getContentType()) :
-					MediaType.APPLICATION_OCTET_STREAM);
+					MediaType.APPLICATION_OCTET_STREAM;
 		}
 		catch (InvalidMediaTypeException ex) {
 			return null;
@@ -187,6 +217,13 @@ public final class ConsumesRequestCondition extends AbstractRequestCondition<Con
 		return !CollectionUtils.isEmpty(result) ? new ConsumesRequestCondition(result) : null;
 	}
 
+	private boolean hasBody(HttpServletRequest request) {
+		String contentLength = request.getHeader(HttpHeaders.CONTENT_LENGTH);
+		String transferEncoding = request.getHeader(HttpHeaders.TRANSFER_ENCODING);
+		return StringUtils.hasText(transferEncoding) ||
+				(StringUtils.hasText(contentLength) && !contentLength.trim().equals("0"));
+	}
+
 	@Nullable
 	private List<ConsumeMediaTypeExpression> getMatchingExpressions(MediaType contentType) {
 		List<ConsumeMediaTypeExpression> result = null;

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

@@ -18,6 +18,7 @@ package org.springframework.web.servlet.mvc.method.annotation;
 
 import java.lang.reflect.AnnotatedElement;
 import java.lang.reflect.Method;
+import java.lang.reflect.Parameter;
 import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -28,6 +29,8 @@ import javax.servlet.http.HttpServletRequest;
 
 import org.springframework.context.EmbeddedValueResolverAware;
 import org.springframework.core.annotation.AnnotatedElementUtils;
+import org.springframework.core.annotation.MergedAnnotation;
+import org.springframework.core.annotation.MergedAnnotations;
 import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Controller;
 import org.springframework.util.Assert;
@@ -35,6 +38,7 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.StringValueResolver;
 import org.springframework.web.accept.ContentNegotiationManager;
 import org.springframework.web.bind.annotation.CrossOrigin;
+import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.cors.CorsConfiguration;
@@ -43,6 +47,7 @@ import org.springframework.web.servlet.handler.MatchableHandlerMapping;
 import org.springframework.web.servlet.handler.RequestMatchResult;
 import org.springframework.web.servlet.mvc.condition.AbstractRequestCondition;
 import org.springframework.web.servlet.mvc.condition.CompositeRequestCondition;
+import org.springframework.web.servlet.mvc.condition.ConsumesRequestCondition;
 import org.springframework.web.servlet.mvc.condition.RequestCondition;
 import org.springframework.web.servlet.mvc.method.RequestMappingInfo;
 import org.springframework.web.servlet.mvc.method.RequestMappingInfoHandlerMapping;
@@ -332,6 +337,31 @@ public class RequestMappingHandlerMapping extends RequestMappingInfoHandlerMappi
 		}
 	}
 
+	@Override
+	public void registerMapping(RequestMappingInfo mapping, Object handler, Method method) {
+		super.registerMapping(mapping, handler, method);
+		updateConsumesCondition(mapping, method);
+	}
+
+	@Override
+	protected void registerHandlerMethod(Object handler, Method method, RequestMappingInfo mapping) {
+		super.registerHandlerMethod(handler, method, mapping);
+		updateConsumesCondition(mapping, method);
+	}
+
+	private void updateConsumesCondition(RequestMappingInfo info, Method method) {
+		ConsumesRequestCondition condition = info.getConsumesCondition();
+		if (!condition.isEmpty()) {
+			for (Parameter parameter : method.getParameters()) {
+				MergedAnnotation<RequestBody> annot = MergedAnnotations.from(parameter).get(RequestBody.class);
+				if (annot.isPresent()) {
+					condition.setBodyRequired(annot.getBoolean("required"));
+					break;
+				}
+			}
+		}
+	}
+
 	@Override
 	public RequestMatchResult match(HttpServletRequest request, String pattern) {
 		RequestMappingInfo info = RequestMappingInfo.paths(pattern).options(this.config).build();