Fix standard multipart binding + Polish

Fixing standard multipart binding when multiple parts share
the same name.

Uncomment previously @Ignored tests now that Jetty supports
Servlet 3.0 spec.

Issue: SPR-10591

spring-web/src/main/java/org/springframework/web/bind/support/WebRequestDataBinder.java

@@ -17,6 +17,8 @@
 package org.springframework.web.bind.support;
 
 import java.io.IOException;
+import java.util.List;
+import java.util.Map;
 
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServletRequest;
@@ -24,6 +26,8 @@ import javax.servlet.http.Part;
 
 import org.springframework.beans.MutablePropertyValues;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
 import org.springframework.validation.BindException;
 import org.springframework.web.bind.WebDataBinder;
@@ -119,7 +123,7 @@ public class WebRequestDataBinder extends WebDataBinder {
 			}
 			else if (ClassUtils.hasMethod(HttpServletRequest.class, "getParts")) {
 				HttpServletRequest serlvetRequest = ((NativeWebRequest) request).getNativeRequest(HttpServletRequest.class);
-				new Servlet3MultipartHelper().bindParts(serlvetRequest, mpvs);
+				new Servlet3MultipartHelper(isBindEmptyMultipartFiles()).bindParts(serlvetRequest, mpvs);
 			}
 		}
 		doBind(mpvs);
@@ -154,10 +158,30 @@ public class WebRequestDataBinder extends WebDataBinder {
 	 */
 	private static class Servlet3MultipartHelper {
 
+		private final boolean bindEmptyMultipartFiles;
+
+
+		public Servlet3MultipartHelper(boolean bindEmptyMultipartFiles) {
+			this.bindEmptyMultipartFiles = bindEmptyMultipartFiles;
+		}
+
+
 		public void bindParts(HttpServletRequest request, MutablePropertyValues mpvs) {
 			try {
-				for(Part part : request.getParts()) {
-					mpvs.add(part.getName(), part);
+				MultiValueMap<String, Part> map = new LinkedMultiValueMap<String, Part>();
+				for (Part part : request.getParts()) {
+					map.add(part.getName(), part);
+				}
+				for (Map.Entry<String, List<Part>> entry: map.entrySet()) {
+					if (entry.getValue().size() == 1) {
+						Part part = entry.getValue().get(0);
+						if (this.bindEmptyMultipartFiles || part.getSize() > 0) {
+							mpvs.add(entry.getKey(), part);
+						}
+					}
+					else {
+						mpvs.add(entry.getKey(), entry.getValue());
+					}
 				}
 			}
 			catch (IOException ex) {

spring-web/src/test/java/org/springframework/web/bind/support/WebRequestDataBinderIntegrationTests.java

@@ -21,7 +21,6 @@ import java.util.List;
 
 import javax.servlet.MultipartConfigElement;
 import javax.servlet.ServletException;
-import javax.servlet.annotation.MultipartConfig;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
@@ -38,7 +37,6 @@ import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
 import org.springframework.http.MediaType;
 import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
-import org.springframework.mock.web.test.MockMultipartFile;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.SocketUtils;
@@ -109,7 +107,7 @@ public class WebRequestDataBinderIntegrationTests {
 		partsServlet.setBean(bean);
 
 		MultiValueMap<String, Object> parts = new LinkedMultiValueMap<String, Object>();
-		MockMultipartFile firstPart = new MockMultipartFile("fileName", "aValue".getBytes());
+		Resource firstPart = new ClassPathResource("/org/springframework/http/converter/logo.jpg");
 		parts.add("firstPart", firstPart);
 		parts.add("secondPart", "secondValue");
 
@@ -134,7 +132,7 @@ public class WebRequestDataBinderIntegrationTests {
 		template.postForLocation(baseUrl + "/partlist", parts);
 
 		assertNotNull(bean.getPartList());
-		assertEquals(parts.size(), bean.getPartList().size());
+		assertEquals(parts.get("partList").size(), bean.getPartList().size());
 	}
 
 

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

@@ -19,13 +19,14 @@ package org.springframework.web.servlet.mvc.method.annotation;
 import java.net.URI;
 import java.util.Arrays;
 
+import javax.servlet.MultipartConfigElement;
+
 import org.eclipse.jetty.server.Server;
 import org.eclipse.jetty.servlet.ServletContextHandler;
 import org.eclipse.jetty.servlet.ServletHolder;
 import org.junit.AfterClass;
 import org.junit.Before;
 import org.junit.BeforeClass;
-import org.junit.Ignore;
 import org.junit.Test;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -62,6 +63,7 @@ import static org.junit.Assert.*;
  * Test access to parts of a multipart request with {@link RequestPart}.
  *
  * @author Rossen Stoyanchev
+ * @author Brian Clozel
  */
 public class RequestPartIntegrationTests {
 
@@ -91,10 +93,9 @@ public class RequestPartIntegrationTests {
 		ServletHolder standardResolverServlet = new ServletHolder(DispatcherServlet.class);
 		standardResolverServlet.setInitParameter("contextConfigLocation", config.getName());
 		standardResolverServlet.setInitParameter("contextClass", AnnotationConfigWebApplicationContext.class.getName());
+		standardResolverServlet.getRegistration().setMultipartConfig(new MultipartConfigElement(""));
 		handler.addServlet(standardResolverServlet, "/standard-resolver/*");
 
-		// TODO: add Servlet 3.0 test case without MultipartResolver
-
 		server.setHandler(handler);
 		server.start();
 	}
@@ -123,7 +124,6 @@ public class RequestPartIntegrationTests {
 	}
 
 	@Test
-	@Ignore("jetty 6.1.9 doesn't support Servlet 3.0")
 	public void standardMultipartResolver() throws Exception {
 		testCreate(baseUrl + "/standard-resolver/test");
 	}