Add javax.servlet.http.Part support for data binding

Prior to this commit, Multipart databinding would only support
MultiPartFile databinding using commons-multipart.

Now the WebRequestDataBinder supports Part and List<Part>
databinding for Servlet 3.0 compliant containers.

Issue: SPR-10591

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * 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.
@@ -16,11 +16,20 @@
 
 package org.springframework.web.bind.support;
 
+import java.io.IOException;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.Part;
+
 import org.springframework.beans.MutablePropertyValues;
+import org.springframework.util.ClassUtils;
+import org.springframework.util.StringUtils;
 import org.springframework.validation.BindException;
 import org.springframework.web.bind.WebDataBinder;
 import org.springframework.web.context.request.NativeWebRequest;
 import org.springframework.web.context.request.WebRequest;
+import org.springframework.web.multipart.MultipartException;
 import org.springframework.web.multipart.MultipartRequest;
 
 /**
@@ -50,6 +59,7 @@ import org.springframework.web.multipart.MultipartRequest;
  * ...</pre>
  *
  * @author Juergen Hoeller
+ * @author Brian Clozel
  * @since 2.5.2
  * @see #bind(org.springframework.web.context.request.WebRequest)
  * @see #registerCustomEditor
@@ -59,6 +69,7 @@ import org.springframework.web.multipart.MultipartRequest;
  */
 public class WebRequestDataBinder extends WebDataBinder {
 
+
 	/**
 	 * Create a new WebRequestDataBinder instance, with default object name.
 	 * @param target the target object to bind onto (or {@code null}
@@ -89,22 +100,27 @@ public class WebRequestDataBinder extends WebDataBinder {
 	 * <p>Multipart files are bound via their parameter name, just like normal
 	 * HTTP parameters: i.e. "uploadedFile" to an "uploadedFile" bean property,
 	 * invoking a "setUploadedFile" setter method.
-	 * <p>The type of the target property for a multipart file can be MultipartFile,
+	 * <p>The type of the target property for a multipart file can be Part, MultipartFile,
 	 * byte[], or String. The latter two receive the contents of the uploaded file;
 	 * all metadata like original file name, content type, etc are lost in those cases.
 	 * @param request request with parameters to bind (can be multipart)
 	 * @see org.springframework.web.multipart.MultipartRequest
 	 * @see org.springframework.web.multipart.MultipartFile
-	 * @see #bindMultipartFiles
+	 * @see javax.servlet.http.Part
 	 * @see #bind(org.springframework.beans.PropertyValues)
 	 */
 	public void bind(WebRequest request) {
 		MutablePropertyValues mpvs = new MutablePropertyValues(request.getParameterMap());
-		if (request instanceof NativeWebRequest) {
+
+		if(isMultipartRequest(request) && (request instanceof NativeWebRequest)) {
 			MultipartRequest multipartRequest = ((NativeWebRequest) request).getNativeRequest(MultipartRequest.class);
 			if (multipartRequest != null) {
 				bindMultipart(multipartRequest.getMultiFileMap(), mpvs);
 			}
+			else if (ClassUtils.hasMethod(HttpServletRequest.class, "getParts")) {
+				HttpServletRequest serlvetRequest = ((NativeWebRequest) request).getNativeRequest(HttpServletRequest.class);
+				new Servlet3MultipartHelper().bindParts(serlvetRequest, mpvs);
+			}
 		}
 		doBind(mpvs);
 	}
@@ -121,4 +137,37 @@ public class WebRequestDataBinder extends WebDataBinder {
 		}
 	}
 
+	/**
+	 * Check if the request is a multipart request (by checking its Content-Type header).
+	 *
+	 * @param request request with parameters to bind
+	 */
+	private boolean isMultipartRequest(WebRequest request) {
+		String contentType = request.getHeader("Content-Type");
+		return ((contentType != null) && StringUtils.startsWithIgnoreCase(contentType, "multipart"));
+	}
+
+
+	/**
+	 * Encapsulate Part binding code for Servlet 3.0+ only containers.
+	 * @see javax.servlet.http.Part
+	 */
+	private static class Servlet3MultipartHelper {
+
+		public void bindParts(HttpServletRequest request, MutablePropertyValues mpvs) {
+			try {
+				for(Part part : request.getParts()) {
+					mpvs.add(part.getName(), part);
+				}
+			}
+			catch (IOException ex) {
+				throw new MultipartException("Failed to get request parts", ex);
+			}
+			catch(ServletException ex) {
+				throw new MultipartException("Failed to get request parts", ex);
+			}
+		}
+
+	}
+
 }