Resolve native header values with @Header

The @Header annotation in spring-messaging now resolves values from the
nested "nativeHeaders" map as well as top-level header map values.

In case of ambiguity (a value that exists in both), the top-level map
value is used and a warning message is printed. This is unlikly in most
cases but can be resolved by prefixing the header value with
"nativeHeadres.myHeader".

Issue: SPR-11326

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -16,12 +16,19 @@
 
 package org.springframework.messaging.handler.annotation.support;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHandlingException;
 import org.springframework.messaging.handler.annotation.Header;
+import org.springframework.messaging.support.NativeMessageHeaderAccessor;
+import org.springframework.util.MultiValueMap;
+
+import java.util.List;
+import java.util.Map;
 
 /**
  * Resolves method parameters annotated with {@link Header @Header}.
@@ -31,6 +38,8 @@ import org.springframework.messaging.handler.annotation.Header;
  */
 public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgumentResolver {
 
+	private static final Log logger = LogFactory.getLog(HeaderMethodArgumentResolver.class);
+
 
 	public HeaderMethodArgumentResolver(ConversionService cs, ConfigurableBeanFactory beanFactory) {
 		super(cs, beanFactory);
@@ -51,7 +60,39 @@ public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgume
 	protected Object resolveArgumentInternal(MethodParameter parameter, Message<?> message,
 			String name) throws Exception {
 
-		return message.getHeaders().get(name);
+		Object headerValue = message.getHeaders().get(name);
+		Object nativeHeaderValue = getNativeHeaderValue(message, name);
+
+		if (headerValue != null && nativeHeaderValue != null) {
+			if (logger.isWarnEnabled()) {
+				logger.warn("Message headers contain two values for the same header '" + name + "', " +
+						"one in the top level header map and a second in the nested map with native headers. " +
+						"Using the value from top level map. " +
+						"Use 'nativeHeader.myHeader' to resolve to the value from the nested native header map." );
+			}
+		}
+
+		return (headerValue != null) ? headerValue : nativeHeaderValue;
+	}
+
+	private Object getNativeHeaderValue(Message<?> message, String name) {
+
+		Map<String, List<String>> nativeHeaders =
+				(Map<String, List<String>>) message.getHeaders().get(NativeMessageHeaderAccessor.NATIVE_HEADERS);
+
+		if (name.startsWith("nativeHeaders.")) {
+			name = name.substring("nativeHeaders.".length());
+			if (logger.isDebugEnabled()) {
+				logger.debug("Looking up native header '" + name + "'");
+			}
+		}
+
+		if ((nativeHeaders == null) || !nativeHeaders.containsKey(name)) {
+			return null;
+		}
+
+		List<?> nativeHeaderValues = nativeHeaders.get(name);
+		return (nativeHeaderValues.size() == 1) ? nativeHeaderValues.get(0) : nativeHeaderValues;
 	}
 
 	@Override

spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -30,6 +30,7 @@ import org.springframework.messaging.Message;
 import org.springframework.messaging.MessageHandlingException;
 import org.springframework.messaging.handler.annotation.Header;
 import org.springframework.messaging.support.MessageBuilder;
+import org.springframework.messaging.support.NativeMessageHeaderAccessor;
 
 import static org.junit.Assert.*;
 
@@ -47,6 +48,7 @@ public class HeaderMethodArgumentResolverTests {
 	private MethodParameter paramNamedDefaultValueStringHeader;
 	private MethodParameter paramSystemProperty;
 	private MethodParameter paramNotAnnotated;
+	private MethodParameter paramNativeHeader;
 
 
 	@Before
@@ -57,11 +59,12 @@ public class HeaderMethodArgumentResolverTests {
 		this.resolver = new HeaderMethodArgumentResolver(new DefaultConversionService(), cxt.getBeanFactory());
 
 		Method method = getClass().getDeclaredMethod("handleMessage",
-				String.class, String.class, String.class, String.class);
+				String.class, String.class, String.class, String.class, String.class);
 		this.paramRequired = new MethodParameter(method, 0);
 		this.paramNamedDefaultValueStringHeader = new MethodParameter(method, 1);
 		this.paramSystemProperty = new MethodParameter(method, 2);
 		this.paramNotAnnotated = new MethodParameter(method, 3);
+		this.paramNativeHeader = new MethodParameter(method, 4);
 
 		this.paramRequired.initParameterNameDiscovery(new DefaultParameterNameDiscoverer());
 		GenericTypeResolver.resolveParameterType(this.paramRequired, HeaderMethodArgumentResolver.class);
@@ -76,7 +79,33 @@ public class HeaderMethodArgumentResolverTests {
 	@Test
 	public void resolveArgument() throws Exception {
 		Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).setHeader("param1", "foo").build();
-		this.resolver.resolveArgument(this.paramRequired, message);
+		Object result = this.resolver.resolveArgument(this.paramRequired, message);
+
+		assertEquals("foo", result);
+	}
+
+	// SPR-11326
+
+	@Test
+	public void resolveArgumentNativeHeader() throws Exception {
+
+		TestMessageHeaderAccessor headers = new TestMessageHeaderAccessor();
+		headers.setNativeHeader("param1", "foo");
+		Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).setHeaders(headers).build();
+
+		assertEquals("foo", this.resolver.resolveArgument(this.paramRequired, message));
+	}
+
+	@Test
+	public void resolveArgumentNativeHeaderAmbiguity() throws Exception {
+
+		TestMessageHeaderAccessor headers = new TestMessageHeaderAccessor();
+		headers.setHeader("param1", "foo");
+		headers.setNativeHeader("param1", "native-foo");
+		Message<byte[]> message = MessageBuilder.withPayload(new byte[0]).setHeaders(headers).build();
+
+		assertEquals("foo", this.resolver.resolveArgument(this.paramRequired, message));
+		assertEquals("native-foo", this.resolver.resolveArgument(this.paramNativeHeader, message));
 	}
 
 	@Test(expected = MessageHandlingException.class)
@@ -112,7 +141,16 @@ public class HeaderMethodArgumentResolverTests {
 			@Header String param1,
 			@Header(value = "name", defaultValue = "bar") String param2,
 			@Header(value = "name", defaultValue="#{systemProperties.systemProperty}") String param3,
-			String param4) {
+			String param4,
+			@Header("nativeHeaders.param1") String nativeHeaderParam1) {
+	}
+
+
+	public static class TestMessageHeaderAccessor extends NativeMessageHeaderAccessor {
+
+		protected TestMessageHeaderAccessor() {
+			super((Message<?>) null);
+		}
 	}
 
 }