INT-2995: Fix HttpHeaders inconsistency

Previously, 'If-Modified-Since' and 'If-Unmodified-Since' HTTP headers were incorrectly processed
within from/to HTTP headers mapping, because Spring-Web `HttpHeaders` has a confusing method name, see:
https://jira.springsource.org/browse/SPR-10600

* fix 'If-Modified-Since' and 'If-Unmodified-Since' processing independently from `HttpHeaders`
* add fallback to formatted string for date ware HTTP headers
* add Spring Integration HTTP proxy scenario test

JIRA: https://jira.springsource.org/browse/INT-2995

spring-integration-http/src/test/java/org/springframework/integration/http/HttpProxyScenarioTests-context.xml

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans:beans xmlns="http://www.springframework.org/schema/integration/http"
+			 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+			 xmlns:beans="http://www.springframework.org/schema/beans"
+			 xmlns:int="http://www.springframework.org/schema/integration"
+			 xsi:schemaLocation="http://www.springframework.org/schema/integration/http http://www.springframework.org/schema/integration/http/spring-integration-http.xsd
+		http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd
+		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
+
+	<beans:bean class="org.springframework.integration.http.inbound.UriPathHandlerMapping"/>
+
+	<inbound-gateway path="/test" request-channel="testChannel"
+					 payload-expression="T(org.springframework.web.context.request.RequestContextHolder).requestAttributes.request.queryString"/>
+
+	<int:publish-subscribe-channel id="testChannel"/>
+
+	<outbound-gateway id="proxyGateway" request-channel="testChannel"
+					  url-expression="'http://testServer/test?' + payload"/>
+
+	<int:bridge input-channel="testChannel" output-channel="checkHeadersChannel"/>
+
+	<int:channel id="checkHeadersChannel">
+		<int:queue/>
+	</int:channel>
+
+</beans:beans>

spring-integration-http/src/test/java/org/springframework/integration/http/HttpProxyScenarioTests.java

@@ -0,0 +1,141 @@
+/*
+ * Copyright 2002-2013 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.integration.http;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+import java.net.URI;
+import java.text.DateFormat;
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+import java.util.Locale;
+import java.util.TimeZone;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mockito;
+import org.mockito.invocation.InvocationOnMock;
+import org.mockito.stubbing.Answer;
+import org.springframework.beans.DirectFieldAccessor;
+import org.springframework.beans.PropertyAccessor;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.integration.Message;
+import org.springframework.integration.MessageHeaders;
+import org.springframework.integration.core.PollableChannel;
+import org.springframework.integration.http.outbound.HttpRequestExecutingMessageHandler;
+import org.springframework.mock.web.MockHttpServletRequest;
+import org.springframework.mock.web.MockHttpServletResponse;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.web.client.RestTemplate;
+import org.springframework.web.context.request.RequestAttributes;
+import org.springframework.web.context.request.RequestContextHolder;
+import org.springframework.web.context.request.ServletRequestAttributes;
+import org.springframework.web.servlet.HandlerAdapter;
+import org.springframework.web.servlet.HandlerMapping;
+import org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter;
+
+/**
+ * @author Artem Bilan
+ * @since 3.0
+ */
+@ContextConfiguration
+@RunWith(SpringJUnit4ClassRunner.class)
+public class HttpProxyScenarioTests {
+
+	private final HandlerAdapter handlerAdapter = new HttpRequestHandlerAdapter();
+
+	@Autowired
+	private HandlerMapping handlerMapping;
+
+	@Autowired
+	@Qualifier("proxyGateway.handler")
+	private HttpRequestExecutingMessageHandler handler;
+
+	@Autowired
+	private PollableChannel checkHeadersChannel;
+
+	@Test
+	public void testHttpProxyScenario() throws Exception {
+		DateFormat dateFormat = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss zzz", Locale.US);
+		dateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
+
+		Calendar c = Calendar.getInstance();
+		c.set(Calendar.MILLISECOND, 0);
+
+		final long ifModifiedSince = c.getTimeInMillis();
+		String ifModifiedSinceValue = dateFormat.format(ifModifiedSince);
+
+		c.add(Calendar.DATE, -1);
+		long ifUnmodifiedSince = c.getTimeInMillis();
+		final String ifUnmodifiedSinceValue = dateFormat.format(ifUnmodifiedSince);
+
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/test");
+		request.setQueryString("foo=bar&FOO=BAR");
+
+		request.addHeader("If-Modified-Since", ifModifiedSinceValue);
+		request.addHeader("If-Unmodified-Since", ifUnmodifiedSinceValue);
+
+		Object handler = this.handlerMapping.getHandler(request).getHandler();
+		assertNotNull(handler);
+
+		MockHttpServletResponse response = new MockHttpServletResponse();
+
+		RestTemplate template = Mockito.spy(new RestTemplate());
+
+		Mockito.doAnswer(new Answer<ResponseEntity<?>>() {
+			@Override
+			public ResponseEntity<?> answer(InvocationOnMock invocation) throws Throwable {
+				URI uri = (URI) invocation.getArguments()[0];
+				assertEquals(new URI("http://testServer/test?foo=bar&FOO=BAR"), uri);
+				HttpEntity<?> httpEntity = (HttpEntity) invocation.getArguments()[2];
+				HttpHeaders httpHeaders = httpEntity.getHeaders();
+				assertEquals(ifModifiedSince, httpHeaders.getIfNotModifiedSince());
+				assertEquals(ifUnmodifiedSinceValue, httpHeaders.getFirst("If-Unmodified-Since"));
+				return new ResponseEntity<Object>(httpEntity.getHeaders(), HttpStatus.OK);
+			}
+		}).when(template).exchange(Mockito.any(URI.class), Mockito.any(HttpMethod.class),
+				Mockito.any(HttpEntity.class),  (Class<?>) Mockito.any(Class.class));
+
+		PropertyAccessor dfa = new DirectFieldAccessor(this.handler);
+		dfa.setPropertyValue("restTemplate", template);
+
+		RequestAttributes attributes = new ServletRequestAttributes(request);
+		RequestContextHolder.setRequestAttributes(attributes);
+
+		this.handlerAdapter.handle(request, response, handler);
+
+		assertNull(response.getHeaderValue("If-Modified-Since"));
+		assertNull(response.getHeaderValue("If-Unmodified-Since"));
+
+		Message<?> message = this.checkHeadersChannel.receive(2000);
+		MessageHeaders headers = message.getHeaders();
+
+		assertEquals(ifModifiedSince, headers.get("If-Modified-Since"));
+		assertEquals(ifUnmodifiedSince, headers.get("If-Unmodified-Since"));
+
+	}
+
+}

spring-integration-http/src/test/java/org/springframework/integration/http/support/DefaultHttpHeaderMapperFromMessageInboundTests.java

@@ -25,6 +25,7 @@ import java.net.URI;
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.Arrays;
+import java.util.Calendar;
 import java.util.Collections;
 import java.util.Date;
 import java.util.HashMap;
@@ -48,6 +49,7 @@ import org.springframework.util.CollectionUtils;
  * @author Oleg Zhurakousky
  * @author Mark Fisher
  * @author Gunnar Hillert
+ * @author Artem Bilan
  * @since 2.0.1
  */
 public class DefaultHttpHeaderMapperFromMessageInboundTests {
@@ -549,13 +551,27 @@ public class DefaultHttpHeaderMapperFromMessageInboundTests {
         HeaderMapper<HttpHeaders> mapper  = DefaultHttpHeaderMapper.inboundMapper();
         HttpHeaders headers = new HttpHeaders();
         // suppressed in response on inbound, by default
-        headers.put("Content-Length", Arrays.asList(new String[] {"3"}));
+        headers.put("Content-Length", Arrays.asList("3"));
         Map<String, Object> messageHeaders = mapper.toHeaders(headers);
         headers = new HttpHeaders();
         mapper.fromHeaders(new MessageHeaders(messageHeaders), headers);
         assertNull(headers.get("Content-Length"));
     }
 
+	@Test
+	public void testInt2995IfModifiedSince() throws Exception{
+		HeaderMapper<HttpHeaders> mapper  = DefaultHttpHeaderMapper.inboundMapper();
+		Date ifModifiedSince = new Date();
+		long ifModifiedSinceTime = ifModifiedSince.getTime();
+		HttpHeaders headers = new HttpHeaders();
+		headers.setIfModifiedSince(ifModifiedSinceTime);
+		Map<String, ?> result = mapper.toHeaders(headers);
+		Calendar c = Calendar.getInstance();
+		c.setTime(ifModifiedSince);
+		c.set(Calendar.MILLISECOND, 0);
+		assertEquals(c.getTimeInMillis(), result.get("If-Modified-Since"));
+	}
+
 	public static class TestClass {
 
 	}

spring-integration-http/src/test/java/org/springframework/integration/http/support/DefaultHttpHeaderMapperFromMessageOutboundTests.java

@@ -25,17 +25,22 @@ import java.nio.charset.Charset;
 import java.nio.charset.UnsupportedCharsetException;
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
+import java.util.Calendar;
 import java.util.Collections;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.Locale;
 import java.util.Map;
+import java.util.TimeZone;
 
 import org.junit.Test;
+
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
+import org.springframework.integration.Message;
 import org.springframework.integration.MessageHeaders;
 import org.springframework.integration.mapping.HeaderMapper;
+import org.springframework.integration.support.MessageBuilder;
 import org.springframework.util.CollectionUtils;
 
 /**
@@ -668,4 +673,19 @@ public class DefaultHttpHeaderMapperFromMessageOutboundTests {
 		assertEquals(0, messageHeaders.size());
 	}
 
+	public void testInt2995IfModifiedSince() throws Exception{
+		Date ifModifiedSince = new Date();
+		SimpleDateFormat dateFormat = new SimpleDateFormat("EEE MMM dd HH:mm:ss yyyy", Locale.US);
+		dateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
+		String value = dateFormat.format(ifModifiedSince);
+		Message<?> testMessage = MessageBuilder.withPayload("foo").setHeader("If-Modified-Since", value).build();
+		HeaderMapper<HttpHeaders> mapper  = DefaultHttpHeaderMapper.outboundMapper();
+		HttpHeaders headers = new HttpHeaders();
+		mapper.fromHeaders(testMessage.getHeaders(), headers);
+		Calendar c = Calendar.getInstance();
+		c.setTime(ifModifiedSince);
+		c.set(Calendar.MILLISECOND, 0);
+		assertEquals(c.getTimeInMillis(), headers.getIfNotModifiedSince());
+	}
+
 }