Add @RequestAttribute with servlet-based support

Issue: SPR-13894

spring-web/src/main/java/org/springframework/web/bind/annotation/RequestAttribute.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2002-2015 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
+ *
+ *      http://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.web.bind.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.core.annotation.AliasFor;
+
+/**
+ * Annotation to bind a method parameter to a request attribute.
+ *
+ * <p>The main motivation is to provide convenient access to request attributes
+ * from a controller method with an optional/required check and a cast to the
+ * target method parameter type.
+ *
+ * @author Rossen Stoyanchev
+ * @since 4.3
+ * @see RequestMapping
+ * @see SessionAttribute
+ */
+@Target(ElementType.PARAMETER)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface RequestAttribute {
+
+	/**
+	 * Alias for {@link #name}.
+	 */
+	@AliasFor("name")
+	String value() default "";
+
+	/**
+	 * The name of the request attribute to bind to.
+	 * <p>The default name is inferred from the method parameter name.
+	 */
+	@AliasFor("value")
+	String name() default "";
+
+	/**
+	 * Whether the request attribute is required.
+	 * <p>Defaults to {@code true}, leading to an exception being thrown
+	 * if the attribute is missing. Switch this to {@code false} if you prefer
+	 * a {@code null} or Java 1.8+ {@code java.util.Optional} if the attribute
+	 * doesn't exist.
+	 */
+	boolean required() default true;
+
+}

spring-web/src/main/java/org/springframework/web/bind/annotation/RequestMapping.java

@@ -130,6 +130,8 @@ import org.springframework.core.annotation.AliasFor;
  * to existing, permanent session attributes (e.g. user authentication object)
  * as opposed to model attributes temporarily stored in the session as part of
  * a controller workflow via {@link SessionAttributes}.
+ * <li>{@link RequestAttribute @RequestAttribute} annotated parameters for access
+ * to request attributes.
  * <li>{@link org.springframework.http.HttpEntity HttpEntity&lt;?&gt;} parameters
  * (Servlet-only) for access to the Servlet request HTTP headers and contents.
  * The request stream will be converted to the entity body using

spring-web/src/main/java/org/springframework/web/bind/annotation/SessionAttribute.java

@@ -42,6 +42,7 @@ import org.springframework.core.annotation.AliasFor;
  * @since 4.3
  * @see RequestMapping
  * @see SessionAttributes
+ * @see RequestAttribute
  */
 @Target(ElementType.PARAMETER)
 @Retention(RetentionPolicy.RUNTIME)

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

@@ -292,6 +292,7 @@ public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExce
 
 		// Annotation-based argument resolution
 		resolvers.add(new SessionAttributeMethodArgumentResolver());
+		resolvers.add(new RequestAttributeMethodArgumentResolver());
 
 		// Type-based argument resolution
 		resolvers.add(new ServletRequestMethodArgumentResolver());

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

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2002-2016 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
+ *
+ *      http://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.web.servlet.mvc.method.annotation;
+
+import javax.servlet.ServletException;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.web.bind.ServletRequestBindingException;
+import org.springframework.web.bind.annotation.RequestAttribute;
+import org.springframework.web.bind.annotation.ValueConstants;
+import org.springframework.web.context.request.NativeWebRequest;
+import org.springframework.web.context.request.RequestAttributes;
+import org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver;
+
+/**
+ * Resolves method arguments annotated with an @{@link RequestAttribute}.
+ *
+ * @author Rossen Stoyanchev
+ * @since 4.3
+ */
+public class RequestAttributeMethodArgumentResolver extends AbstractNamedValueMethodArgumentResolver {
+
+
+	@Override
+	public boolean supportsParameter(MethodParameter parameter) {
+		return parameter.hasParameterAnnotation(RequestAttribute.class);
+	}
+
+
+	@Override
+	protected NamedValueInfo createNamedValueInfo(MethodParameter parameter) {
+		RequestAttribute annot = parameter.getParameterAnnotation(RequestAttribute.class);
+		return new NamedValueInfo(annot.name(), annot.required(), ValueConstants.DEFAULT_NONE);
+	}
+
+	@Override
+	protected Object resolveName(String name, MethodParameter parameter, NativeWebRequest request){
+		return request.getAttribute(name, RequestAttributes.SCOPE_REQUEST);
+	}
+
+	@Override
+	protected void handleMissingValue(String name, MethodParameter parameter) throws ServletException {
+		throw new ServletRequestBindingException("Missing request attribute '" + name +
+				"' of type " +  parameter.getNestedParameterType().getSimpleName());
+	}
+
+}

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

@@ -601,6 +601,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 		resolvers.add(new ServletCookieValueMethodArgumentResolver(getBeanFactory()));
 		resolvers.add(new ExpressionValueMethodArgumentResolver(getBeanFactory()));
 		resolvers.add(new SessionAttributeMethodArgumentResolver());
+		resolvers.add(new RequestAttributeMethodArgumentResolver());
 
 		// Type-based argument resolution
 		resolvers.add(new ServletRequestMethodArgumentResolver());
@@ -641,6 +642,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 		resolvers.add(new MatrixVariableMapMethodArgumentResolver());
 		resolvers.add(new ExpressionValueMethodArgumentResolver(getBeanFactory()));
 		resolvers.add(new SessionAttributeMethodArgumentResolver());
+		resolvers.add(new RequestAttributeMethodArgumentResolver());
 
 		// Type-based argument resolution
 		resolvers.add(new ServletRequestMethodArgumentResolver());

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

@@ -0,0 +1,185 @@
+/*
+ * Copyright 2002-2016 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
+ *
+ *      http://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.web.servlet.mvc.method.annotation;
+
+import java.lang.reflect.Method;
+import java.util.Optional;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import org.springframework.core.DefaultParameterNameDiscoverer;
+import org.springframework.core.GenericTypeResolver;
+import org.springframework.core.MethodParameter;
+import org.springframework.core.annotation.SynthesizingMethodParameter;
+import org.springframework.core.convert.support.DefaultConversionService;
+import org.springframework.mock.web.test.MockHttpServletRequest;
+import org.springframework.mock.web.test.MockHttpServletResponse;
+import org.springframework.web.bind.ServletRequestBindingException;
+import org.springframework.web.bind.WebDataBinder;
+import org.springframework.web.bind.annotation.RequestAttribute;
+import org.springframework.web.bind.annotation.SessionAttribute;
+import org.springframework.web.bind.support.WebDataBinderFactory;
+import org.springframework.web.bind.support.WebRequestDataBinder;
+import org.springframework.web.context.request.ServletWebRequest;
+import org.springframework.web.method.support.HandlerMethodArgumentResolver;
+import org.springframework.web.method.support.ModelAndViewContainer;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Base class for {@code @RequestAttribute} and {@code @SessionAttribute} method
+ * method argument resolution tests.
+ *
+ * @author Rossen Stoyanchev
+ * @since 4.3
+ */
+public abstract class AbstractRequestAttributesArgumentResolverTests {
+
+	private ServletWebRequest webRequest;
+
+	private HandlerMethodArgumentResolver resolver;
+
+	private Method handleMethod;
+
+
+	@Before
+	public void setUp() throws Exception {
+		HttpServletRequest request = new MockHttpServletRequest();
+		HttpServletResponse response = new MockHttpServletResponse();
+		this.webRequest = new ServletWebRequest(request, response);
+		this.resolver = createResolver();
+		this.handleMethod = AbstractRequestAttributesArgumentResolverTests.class
+				.getDeclaredMethod(getHandleMethodName(), Foo.class, Foo.class, Foo.class, Optional.class);
+	}
+
+
+	protected abstract HandlerMethodArgumentResolver createResolver();
+
+	protected abstract String getHandleMethodName();
+
+	protected abstract int getScope();
+
+
+	@Test
+	public void supportsParameter() throws Exception {
+		assertTrue(this.resolver.supportsParameter(new MethodParameter(this.handleMethod, 0)));
+		assertFalse(this.resolver.supportsParameter(new MethodParameter(this.handleMethod, 4)));
+	}
+
+	@Test
+	public void resolve() throws Exception {
+		MethodParameter param = initMethodParameter(0);
+		try {
+			testResolveArgument(param);
+			fail("Should be required by default");
+		}
+		catch (ServletRequestBindingException ex) {
+			assertTrue(ex.getMessage().startsWith("Missing "));
+		}
+
+		Foo foo = new Foo();
+		this.webRequest.setAttribute("foo", foo, getScope());
+		assertSame(foo, testResolveArgument(param));
+	}
+
+	@Test
+	public void resolveWithName() throws Exception {
+		MethodParameter param = initMethodParameter(1);
+		Foo foo = new Foo();
+		this.webRequest.setAttribute("specialFoo", foo, getScope());
+		assertSame(foo, testResolveArgument(param));
+	}
+
+	@Test
+	public void resolveNotRequired() throws Exception {
+		MethodParameter param = initMethodParameter(2);
+		assertNull(testResolveArgument(param));
+
+		Foo foo = new Foo();
+		this.webRequest.setAttribute("foo", foo, getScope());
+		assertSame(foo, testResolveArgument(param));
+	}
+
+	@Test
+	public void resolveOptional() throws Exception {
+		WebDataBinder dataBinder = new WebRequestDataBinder(null);
+		dataBinder.setConversionService(new DefaultConversionService());
+		WebDataBinderFactory factory = mock(WebDataBinderFactory.class);
+		given(factory.createBinder(this.webRequest, null, "foo")).willReturn(dataBinder);
+
+		MethodParameter param = initMethodParameter(3);
+		Object actual = testResolveArgument(param, factory);
+		assertNotNull(actual);
+		assertEquals(Optional.class, actual.getClass());
+		assertFalse(((Optional) actual).isPresent());
+
+		Foo foo = new Foo();
+		this.webRequest.setAttribute("foo", foo, getScope());
+
+		actual = testResolveArgument(param, factory);
+		assertNotNull(actual);
+		assertEquals(Optional.class, actual.getClass());
+		assertTrue(((Optional) actual).isPresent());
+		assertSame(foo, ((Optional) actual).get());
+	}
+
+	private Object testResolveArgument(MethodParameter param) throws Exception {
+		return testResolveArgument(param, null);
+	}
+
+	private Object testResolveArgument(MethodParameter param, WebDataBinderFactory factory) throws Exception {
+		ModelAndViewContainer mavContainer = new ModelAndViewContainer();
+		return this.resolver.resolveArgument(param, mavContainer, this.webRequest, factory);
+	}
+
+	private MethodParameter initMethodParameter(int parameterIndex) {
+		MethodParameter param = new SynthesizingMethodParameter(this.handleMethod, parameterIndex);
+		param.initParameterNameDiscovery(new DefaultParameterNameDiscoverer());
+		GenericTypeResolver.resolveParameterType(param, this.resolver.getClass());
+		return param;
+	}
+
+
+	@SuppressWarnings("unused")
+	private void handleWithRequestAttribute(
+			@RequestAttribute Foo foo,
+			@RequestAttribute("specialFoo") Foo namedFoo,
+			@RequestAttribute(name="foo", required = false) Foo notRequiredFoo,
+			@RequestAttribute(name="foo") Optional<Foo> optionalFoo) {
+	}
+
+	@SuppressWarnings("unused")
+	private void handleWithSessionAttribute(
+			@SessionAttribute Foo foo,
+			@SessionAttribute("specialFoo") Foo namedFoo,
+			@SessionAttribute(name="foo", required = false) Foo notRequiredFoo,
+			@SessionAttribute(name="foo") Optional<Foo> optionalFoo) {
+	}
+
+	private static class Foo {
+	}
+}

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

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2002-2016 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
+ *
+ *      http://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.web.servlet.mvc.method.annotation;
+
+import org.springframework.web.context.request.RequestAttributes;
+import org.springframework.web.method.support.HandlerMethodArgumentResolver;
+
+
+/**
+ * Unit tests for {@link RequestAttributeMethodArgumentResolver}.
+ * @author Rossen Stoyanchev
+ */
+public class RequestAttributeMethodArgumentResolverTests
+		extends AbstractRequestAttributesArgumentResolverTests {
+
+
+	@Override
+	protected HandlerMethodArgumentResolver createResolver() {
+		return new RequestAttributeMethodArgumentResolver();
+	}
+
+	@Override
+	protected String getHandleMethodName() {
+		return "handleWithRequestAttribute";
+	}
+
+	@Override
+	protected int getScope() {
+		return RequestAttributes.SCOPE_REQUEST;
+	}
+
+}

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

@@ -62,6 +62,7 @@ import org.springframework.web.bind.annotation.CookieValue;
 import org.springframework.web.bind.annotation.InitBinder;
 import org.springframework.web.bind.annotation.ModelAttribute;
 import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestAttribute;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestHeader;
 import org.springframework.web.bind.annotation.RequestParam;
@@ -149,13 +150,14 @@ public class RequestMappingHandlerAdapterIntegrationTests {
 	public void handle() throws Exception {
 		Class<?>[] parameterTypes = new Class<?>[] { int.class, String.class, String.class, String.class, Map.class,
 				Date.class, Map.class, String.class, String.class, TestBean.class, Errors.class, TestBean.class,
-				Color.class, HttpServletRequest.class, HttpServletResponse.class, TestBean.class,
+				Color.class, HttpServletRequest.class, HttpServletResponse.class, TestBean.class, TestBean.class,
 				User.class, OtherUser.class, Model.class, UriComponentsBuilder.class };
 
 		String datePattern = "yyyy.MM.dd";
 		String formattedDate = "2011.03.16";
 		Date date = new GregorianCalendar(2011, Calendar.MARCH, 16).getTime();
 		TestBean sessionAttribute = new TestBean();
+		TestBean requestAttribute = new TestBean();
 
 		request.addHeader("Content-Type", "text/plain; charset=utf-8");
 		request.addHeader("header", "headerValue");
@@ -174,6 +176,7 @@ public class RequestMappingHandlerAdapterIntegrationTests {
 		uriTemplateVars.put("pathvar", "pathvarValue");
 		request.setAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, uriTemplateVars);
 		request.getSession().setAttribute("sessionAttribute", sessionAttribute);
+		request.setAttribute("requestAttribute", requestAttribute);
 
 		HandlerMethod handlerMethod = handlerMethod("handle", parameterTypes);
 		ModelAndView mav = handlerAdapter.handle(request, response, handlerMethod);
@@ -219,6 +222,7 @@ public class RequestMappingHandlerAdapterIntegrationTests {
 		assertEquals(OtherUser.class, model.get("otherUser").getClass());
 
 		assertSame(sessionAttribute, model.get("sessionAttribute"));
+		assertSame(requestAttribute, model.get("requestAttribute"));
 
 		assertEquals(new URI("http://localhost/contextPath/main/path"), model.get("url"));
 	}
@@ -369,6 +373,7 @@ public class RequestMappingHandlerAdapterIntegrationTests {
 						 	HttpServletRequest request,
 						 	HttpServletResponse response,
 							@SessionAttribute TestBean sessionAttribute,
+							@RequestAttribute TestBean requestAttribute,
 						 	User user,
 						 	@ModelAttribute OtherUser otherUser,
 						 	Model model,
@@ -380,6 +385,7 @@ public class RequestMappingHandlerAdapterIntegrationTests {
 					.addAttribute("paramByConvention", paramByConvention).addAttribute("value", value)
 					.addAttribute("customArg", customArg).addAttribute(user)
 					.addAttribute("sessionAttribute", sessionAttribute)
+					.addAttribute("requestAttribute", requestAttribute)
 					.addAttribute("url", builder.path("/path").build().toUri());
 
 			assertNotNull(request);

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

@@ -15,154 +15,31 @@
  */
 package org.springframework.web.servlet.mvc.method.annotation;
 
-import java.lang.reflect.Method;
-import java.util.Optional;
-
-import org.junit.Before;
-import org.junit.Test;
-
-import org.springframework.core.DefaultParameterNameDiscoverer;
-import org.springframework.core.GenericTypeResolver;
-import org.springframework.core.MethodParameter;
-import org.springframework.core.annotation.SynthesizingMethodParameter;
-import org.springframework.core.convert.support.DefaultConversionService;
-import org.springframework.mock.web.test.MockHttpServletRequest;
-import org.springframework.mock.web.test.MockHttpServletResponse;
-import org.springframework.web.bind.ServletRequestBindingException;
-import org.springframework.web.bind.WebDataBinder;
-import org.springframework.web.bind.annotation.SessionAttribute;
-import org.springframework.web.bind.support.WebDataBinderFactory;
-import org.springframework.web.bind.support.WebRequestDataBinder;
-import org.springframework.web.context.request.ServletWebRequest;
-import org.springframework.web.method.support.ModelAndViewContainer;
-
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertSame;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
-import static org.mockito.BDDMockito.given;
-import static org.mockito.Mockito.mock;
+import org.springframework.web.context.request.RequestAttributes;
+import org.springframework.web.method.support.HandlerMethodArgumentResolver;
 
 
 /**
  * Unit tests for {@link SessionAttributeMethodArgumentResolver}.
  * @author Rossen Stoyanchev
  */
-public class SessionAttributeMethodArgumentResolverTests {
-
-	private ServletWebRequest webRequest;
-
-	private MockHttpServletRequest servletRequest;
-
-	private SessionAttributeMethodArgumentResolver resolver;
-
-	private Method handleMethod;
+public class SessionAttributeMethodArgumentResolverTests
+		extends AbstractRequestAttributesArgumentResolverTests {
 
 
-	@Before
-	public void setUp() throws Exception {
-		this.servletRequest = new MockHttpServletRequest();
-		this.webRequest = new ServletWebRequest(this.servletRequest, new MockHttpServletResponse());
-		this.resolver = new SessionAttributeMethodArgumentResolver();
-		this.handleMethod = getClass().getDeclaredMethod("handle", Foo.class, Foo.class,
-				Foo.class, Optional.class, Foo.class);
+	@Override
+	protected HandlerMethodArgumentResolver createResolver() {
+		return new SessionAttributeMethodArgumentResolver();
 	}
 
-
-	@Test
-	public void supportsParameter() throws Exception {
-		assertTrue(this.resolver.supportsParameter(new MethodParameter(this.handleMethod, 0)));
-		assertFalse(this.resolver.supportsParameter(new MethodParameter(this.handleMethod, 4)));
+	@Override
+	protected String getHandleMethodName() {
+		return "handleWithSessionAttribute";
 	}
 
-	@Test
-	public void resolve() throws Exception {
-		MethodParameter param = initMethodParameter(0);
-		try {
-			testResolveArgument(param);
-			fail("Should be required by default");
-		}
-		catch (ServletRequestBindingException ex) {
-			assertTrue(ex.getMessage().startsWith("Missing session attribute"));
-		}
-
-		Foo foo = new Foo();
-		this.servletRequest.getSession().setAttribute("foo", foo);
-		assertSame(foo, testResolveArgument(param));
-	}
-
-	@Test
-	public void resolveWithName() throws Exception {
-		MethodParameter param = initMethodParameter(1);
-		Foo foo = new Foo();
-		this.servletRequest.getSession().setAttribute("specialFoo", foo);
-		assertSame(foo, testResolveArgument(param));
-	}
-
-	@Test
-	public void resolveNotRequired() throws Exception {
-		MethodParameter param = initMethodParameter(2);
-		assertNull(testResolveArgument(param));
-
-		Foo foo = new Foo();
-		this.servletRequest.getSession().setAttribute("foo", foo);
-		assertSame(foo, testResolveArgument(param));
-	}
-
-	@Test
-	public void resolveOptional() throws Exception {
-		WebDataBinder dataBinder = new WebRequestDataBinder(null);
-		dataBinder.setConversionService(new DefaultConversionService());
-		WebDataBinderFactory factory = mock(WebDataBinderFactory.class);
-		given(factory.createBinder(this.webRequest, null, "foo")).willReturn(dataBinder);
-
-		MethodParameter param = initMethodParameter(3);
-		Object actual = testResolveArgument(param, factory);
-		assertNotNull(actual);
-		assertEquals(Optional.class, actual.getClass());
-		assertFalse(((Optional) actual).isPresent());
-
-		Foo foo = new Foo();
-		this.servletRequest.getSession().setAttribute("foo", foo);
-
-		actual = testResolveArgument(param, factory);
-		assertNotNull(actual);
-		assertEquals(Optional.class, actual.getClass());
-		assertTrue(((Optional) actual).isPresent());
-		assertSame(foo, ((Optional) actual).get());
-	}
-
-
-	private Object testResolveArgument(MethodParameter param) throws Exception {
-		return testResolveArgument(param, null);
-	}
-
-	private Object testResolveArgument(MethodParameter param, WebDataBinderFactory factory) throws Exception {
-		ModelAndViewContainer mavContainer = new ModelAndViewContainer();
-		return this.resolver.resolveArgument(param, mavContainer, this.webRequest, factory);
-	}
-
-	private MethodParameter initMethodParameter(int parameterIndex) {
-		MethodParameter param = new SynthesizingMethodParameter(this.handleMethod, parameterIndex);
-		param.initParameterNameDiscovery(new DefaultParameterNameDiscoverer());
-		GenericTypeResolver.resolveParameterType(param, SessionAttributeMethodArgumentResolver.class);
-		return param;
-	}
-
-
-	@SuppressWarnings("unused")
-	private void handle(
-			@SessionAttribute Foo foo,
-			@SessionAttribute("specialFoo") Foo namedFoo,
-			@SessionAttribute(name="foo", required = false) Foo notRequiredFoo,
-			@SessionAttribute(name="foo") Optional<Foo> optionalFoo,
-			Foo notAnnotatedFoo) {
-	}
-
-	private static class Foo {
+	@Override
+	protected int getScope() {
+		return RequestAttributes.SCOPE_SESSION;
 	}
 
 }

src/asciidoc/web-mvc.adoc

@@ -1254,6 +1254,7 @@ multiple requests are allowed to access a session concurrently.
   session attributes (e.g. user authentication object) as opposed to model
   attributes temporarily stored in the session as part of a controller workflow
   via `@SessionAttributes`.
+* `@RequestAttribute` annotated parameters for access to request attributes.
 * `HttpEntity<?>` parameters for access to the Servlet request HTTP headers and
   contents. The request stream will be converted to the entity body using
   ++HttpMessageConverter++s. See <<mvc-ann-httpentity>>.
@@ -1794,6 +1795,23 @@ workflow consider using `SessionAttributes` as described in
 <<mvc-ann-sessionattrib>>.
 
 
+[[mvc-ann-requestattrib]]
+==== Using @RequestAttribute to access request attributes
+
+Similar to `@SessionAttribute` the `@RequestAttribute` annotation can be used to
+access pre-existing request attributes created by a filter or interceptor:
+
+[source,java,indent=0]
+[subs="verbatim,quotes"]
+----
+	@RequestMapping("/")
+	public String handle(**@RequestAttribute** Client client) {
+		// ...
+	}
+----
+
+
+
 
 [[mvc-ann-form-urlencoded-data]]
 ==== Working with "application/x-www-form-urlencoded" data

src/asciidoc/whats-new.adoc

@@ -665,6 +665,7 @@ Spring 4.3 also improves the caching abstraction as follows:
 * New `@RestControllerAdvice` annotation with combined `@ControllerAdvice` with `@ResponseBody` semantics.
 * `@ResponseStatus` supported on the class level and inherited on all methods.
 * New `@SessionAttribute` annotation for access to session attributes (see <<mvc-ann-sessionattrib-global, example>>).
+* New `@RequestAttribute` annotation for access to session attributes (see <<mvc-ann-requestattrib, example>>).
 * `AsyncRestTemplate` supports request interception.
 
 === WebSocket Messaging Improvements