RedirectViews should always use RESPONSE_STATUS_ATTRIBUTE

By default, RedirectViews have http10Compatible set to true, which means
that they use HTTP 302 as a default HTTP response status. Setting this
property to false make RedirectViews use HTTP 303 by default.

Now when set to false, RedirectViews also don't use the
RESPONSE_STATUS_ATTRIBUTE request attribute as a response HTTP if it is
available.

This commit makes both configuration choices behave the same regarding
this request attribute: use it as a response status if it's available.

Issue: SPR-13208

Author: bclozel

spring-webmvc/src/main/java/org/springframework/web/servlet/view/RedirectView.java

@@ -591,10 +591,15 @@ protected void sendRedirect(HttpServletRequest request, HttpServletResponse resp
 
 		String encodedRedirectURL = response.encodeRedirectURL(targetUrl);
 		if (http10Compatible) {
+			HttpStatus attributeStatusCode = (HttpStatus) request.getAttribute(View.RESPONSE_STATUS_ATTRIBUTE);
 			if (this.statusCode != null) {
 				response.setStatus(this.statusCode.value());
 				response.setHeader("Location", encodedRedirectURL);
 			}
+			else if (attributeStatusCode != null) {
+				response.setStatus(attributeStatusCode.value());
+				response.setHeader("Location", encodedRedirectURL);
+			}
 			else {
 				// Send status code 302 by default.
 				response.sendRedirect(encodedRedirectURL);

spring-webmvc/src/test/java/org/springframework/web/servlet/view/RedirectViewTests.java

@@ -109,6 +109,18 @@ public void explicitStatusCodeHttp10() throws Exception {
 		assertEquals("http://url.somewhere.com", response.getHeader("Location"));
 	}
 
+	@Test
+	public void attributeStatusCodeHttp10() throws Exception {
+		RedirectView rv = new RedirectView();
+		rv.setUrl("http://url.somewhere.com");
+		MockHttpServletRequest request = createRequest();
+		request.setAttribute(View.RESPONSE_STATUS_ATTRIBUTE, HttpStatus.CREATED);
+		MockHttpServletResponse response = new MockHttpServletResponse();
+		rv.render(new HashMap<String, Object>(), request, response);
+		assertEquals(201, response.getStatus());
+		assertEquals("http://url.somewhere.com", response.getHeader("Location"));
+	}
+
 	@Test
 	public void attributeStatusCodeHttp11() throws Exception {
 		RedirectView rv = new RedirectView();