added multipart/mixed support

README.md

@@ -256,3 +256,10 @@ public interface DownloadClient {
   }
 }
 ```
+### multipart/mixed
+Replace `SpringManyMultipartFilesReader` in the `DownloadClient` example above with `SpringMultipartMixedReader`.
+
+#### TODO
+- update the maven dependency versions, they are out of date
+- refactor a common SpringMultiXXX base class with the common parts of the two Spring readers
+- increment the versions -> 3.8.1

feign-form-spring/src/main/java/feign/form/spring/converter/SpringMultipartMixedReader.java

@@ -0,0 +1,182 @@
+/*
+ * Copyright 2019 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 feign.form.spring.converter;
+
+import static feign.form.util.CharsetUtil.UTF_8;
+import static lombok.AccessLevel.PRIVATE;
+import static org.springframework.http.HttpHeaders.CONTENT_DISPOSITION;
+import static org.springframework.http.HttpHeaders.CONTENT_TYPE;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.LinkedList;
+import java.util.Map;
+import java.util.regex.Pattern;
+
+import lombok.experimental.FieldDefaults;
+import lombok.val;
+import org.apache.commons.fileupload.MultipartStream;
+import org.springframework.http.HttpInputMessage;
+import org.springframework.http.HttpOutputMessage;
+import org.springframework.http.MediaType;
+import org.springframework.http.converter.AbstractHttpMessageConverter;
+import org.springframework.http.converter.FormHttpMessageConverter;
+import org.springframework.http.converter.HttpMessageConversionException;
+import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.http.converter.HttpMessageNotReadableException;
+import org.springframework.util.StringUtils;
+import org.springframework.web.multipart.MultipartFile;
+
+/**
+ * Implementation of {@link HttpMessageConverter} that can read multipart/form-data HTTP bodies
+ * (writing is not handled because that is already supported by {@link FormHttpMessageConverter}).
+ * <p>
+ * This reader supports an array of {@link MultipartFile} as the mapping return class type - each
+ * multipart body is read into an underlying byte array (in memory) implemented via
+ * {@link ByteArrayMultipartFile}.
+ */
+@FieldDefaults(level = PRIVATE, makeFinal = true)
+public class SpringMultipartMixedReader extends AbstractHttpMessageConverter<MultipartFile[]> {
+
+  private static final Pattern NEWLINES_PATTERN = Pattern.compile("\\R");
+
+  private static final Pattern COLON_PATTERN = Pattern.compile(":");
+
+  private static final Pattern SEMICOLON_PATTERN = Pattern.compile(";");
+
+  private static final Pattern EQUALITY_SIGN_PATTERN = Pattern.compile("=");
+
+  int bufSize;
+
+  /**
+   * Construct an {@code AbstractHttpMessageConverter} that can read mulitpart/form-data.
+   *
+   * @param bufSize The size of the buffer (in bytes) to read the HTTP multipart body.
+   */
+  public SpringMultipartMixedReader (int bufSize) {
+    super(new MediaType("multipart", "mixed")); // TODO later version of Spring MVC MediaType has this
+    this.bufSize = bufSize;
+  }
+
+  @Override
+  protected boolean canWrite (MediaType mediaType) {
+    return false; // Class NOT meant for writing multipart/form-data HTTP bodies
+  }
+
+  @Override
+  protected boolean supports (Class<?> clazz) {
+    return MultipartFile[].class == clazz;
+  }
+
+  @Override
+  protected MultipartFile[] readInternal (Class<? extends MultipartFile[]> clazz, HttpInputMessage inputMessage
+  ) throws IOException {
+    val headers = inputMessage.getHeaders();
+
+    MediaType contentType = headers.getContentType();
+    if (contentType == null) {
+      throw new HttpMessageNotReadableException("Content-Type is missing.", inputMessage);
+    }
+
+    val boundaryBytes = getMultiPartBoundary(contentType);
+    MultipartStream multipartStream = new MultipartStream(inputMessage.getBody(), boundaryBytes, bufSize, null);
+
+    val multiparts = new LinkedList<ByteArrayMultipartFile>();
+    for (boolean nextPart = multipartStream.skipPreamble(); nextPart; nextPart = multipartStream.readBoundary()) {
+      ByteArrayMultipartFile multiPart;
+      try {
+        multiPart = readMultiPart(multipartStream);
+      } catch (Exception e) {
+        throw new HttpMessageNotReadableException("Multipart body could not be read.", e, inputMessage);
+      }
+      multiparts.add(multiPart);
+    }
+    return multiparts.toArray(new ByteArrayMultipartFile[0]);
+  }
+
+  @Override
+  protected void writeInternal (MultipartFile[] byteArrayMultipartFiles, HttpOutputMessage outputMessage) {
+    throw new UnsupportedOperationException(getClass().getSimpleName() + " does not support writing to HTTP body.");
+  }
+
+  private byte[] getMultiPartBoundary (MediaType contentType) {
+    val boundaryString = unquote(contentType.getParameter("boundary"));
+    if (StringUtils.isEmpty(boundaryString)) {
+      throw new HttpMessageConversionException("Content-Type missing boundary information.");
+    }
+    return boundaryString.getBytes(UTF_8);
+  }
+
+  private ByteArrayMultipartFile readMultiPart (MultipartStream multipartStream) throws IOException {
+    val multiPartHeaders = splitIntoKeyValuePairs(
+        multipartStream.readHeaders(),
+        NEWLINES_PATTERN,
+        COLON_PATTERN,
+        false
+    );
+
+    val contentDisposition = splitIntoKeyValuePairs(
+        multiPartHeaders.get(CONTENT_DISPOSITION),
+        SEMICOLON_PATTERN,
+        EQUALITY_SIGN_PATTERN,
+        true
+    );
+
+    val bodyStream = new ByteArrayOutputStream();
+    multipartStream.readBodyData(bodyStream);
+    return new ByteArrayMultipartFile(
+        contentDisposition.get("name"),
+        contentDisposition.get("filename"),
+        multiPartHeaders.get(CONTENT_TYPE),
+        bodyStream.toByteArray()
+    );
+  }
+
+  private Map<String, String> splitIntoKeyValuePairs (String str, Pattern entriesSeparatorPattern,
+                                                      Pattern keyValueSeparatorPattern, boolean unquoteValue
+  ) {
+    val keyValuePairs = new IgnoreKeyCaseMap();
+    if (!StringUtils.isEmpty(str)) {
+      val tokens = entriesSeparatorPattern.split(str);
+      for (val token : tokens) {
+        val pair = keyValueSeparatorPattern.split(token.trim(), 2);
+        val key = pair[0].trim();
+        val value = pair.length > 1
+                    ? pair[1].trim()
+                    : "";
+
+        keyValuePairs.put(key, unquoteValue
+                               ? unquote(value)
+                               : value);
+      }
+    }
+    return keyValuePairs;
+  }
+
+  private String unquote (String value) {
+    if (value == null) {
+      return null;
+    }
+    return isSurroundedBy(value, "\"") || isSurroundedBy(value, "'")
+         ? value.substring(1, value.length() - 1)
+         : value;
+  }
+
+  private boolean isSurroundedBy (String value, String preSuffix) {
+    return value.length() > 1 && value.startsWith(preSuffix) && value.endsWith(preSuffix);
+  }
+}

feign-form-spring/src/test/java/feign/form/feign/spring/DownloadClient.java

@@ -35,7 +35,7 @@
 
 @FeignClient(
     name = "multipart-download-support-service",
-    url = "http://localhost:8081",
+    url = "http://localhost:8082",
     configuration = DownloadClient.ClientConfiguration.class
 )
 public interface DownloadClient {

feign-form-spring/src/test/java/feign/form/feign/spring/SpringMultipartDecoderTest.java

@@ -33,7 +33,7 @@
     webEnvironment = DEFINED_PORT,
     classes = Server.class,
     properties = {
-        "server.port=8081",
+        "server.port=8082",
         "feign.hystrix.enabled=false"
     }
 )