Improve decoding support for multipart filename

StandardMultipartHttpServletRequest now properly decodes RFC-5987
encoded filenames (i.e. filename*) by delegating to ContentDisposition
and also support RFC-2047 syntax through javax.mail MimeUtility.

Issue: SPR-15205

spring-web/src/test/java/org/springframework/web/multipart/support/StandardMultipartHttpServletRequestTests.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2002-2017 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.multipart.support;
+
+import org.junit.Test;
+
+import org.springframework.mock.web.test.MockHttpServletRequest;
+import org.springframework.mock.web.test.MockPart;
+import org.springframework.web.multipart.MultipartFile;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+/**
+ * Unit tests for {@link StandardMultipartHttpServletRequest}.
+ * @author Rossen Stoyanchev
+ */
+public class StandardMultipartHttpServletRequestTests {
+
+
+	@Test
+	public void filename() throws Exception {
+
+		StandardMultipartHttpServletRequest request = getRequest(
+				"file", "form-data; name=\"file\"; filename=\"myFile.txt\"");
+
+		MultipartFile multipartFile = request.getFile("file");
+		assertNotNull(multipartFile);
+		assertEquals("myFile.txt", multipartFile.getOriginalFilename());
+	}
+
+	@Test // SPR-13319
+	public void filenameRfc5987() throws Exception {
+
+		StandardMultipartHttpServletRequest request = getRequest(
+				"file", "form-data; name=\"file\"; filename*=\"UTF-8''foo-%c3%a4-%e2%82%ac.html\"");
+
+		MultipartFile multipartFile = request.getFile("file");
+		assertNotNull(multipartFile);
+		assertEquals("foo-ä-€.html", multipartFile.getOriginalFilename());
+	}
+
+	@Test // SPR-15205
+	public void filenameRfc2047() throws Exception {
+
+		StandardMultipartHttpServletRequest request = getRequest(
+				"file", "form-data; name=\"file\"; filename=\"=?UTF-8?Q?Declara=C3=A7=C3=A3o.pdf?=\"");
+
+		MultipartFile multipartFile = request.getFile("file");
+		assertNotNull(multipartFile);
+		assertEquals("Declaração.pdf", multipartFile.getOriginalFilename());
+	}
+
+
+	private StandardMultipartHttpServletRequest getRequest(String name, String dispositionValue) {
+		MockHttpServletRequest request = new MockHttpServletRequest();
+		MockPart part = new MockPart(name, new byte[0]);
+		part.getHeaders().set("Content-Disposition", dispositionValue);
+		request.addPart(part);
+		return new StandardMultipartHttpServletRequest(request);
+	}
+
+}