A REST service that can use both JSON and Multipart Form

Question

I need to create a method in Spring MVC that can handle JSON and Multipart Form requests.

This is my method signature:

@RequestMapping(value = { "/upload_image" }, method = RequestMethod.POST) public @ResponseBody void uploadImage(final ImageDTO image) 

The ImageDTO class is as follows:

 public class ImageDTO { private String imageUrl; private Long imageId; private MultipartFile image; public String getImageUrl() { return imageUrl; } public void setImageUrl(final String url) { this.imageUrl = url; } public Long getImageId() { return imageId; } public void setImageId(final Long imageId) { this.imageId = imageId; } public MultipartFile getImage() { return image; } public void setImage(MultipartFile image) { this.image = image; } } 

So, the scenario is that I need to support two scenarios: 1. Download the download from the form where the Content-Type is multi-part (all DTO members are non-zero) 2. Upload the image using JSON using ONLY imageUrl. In this case, the request body is as follows:

 { "imageId":"1236", "imageUrl":"http://some.image.url", "image":null } 

The current implementation handles a multi-page request well, but when sending JSON, the ImageDTO object contains NULL in all its members.

Is it possible for the same method to process both types of content?

Thanks.

Answer 1

To get JSON, you need to tag ImageDTO with @RequestBody

 @RequestMapping(value = { "/upload_image" }, method = RequestMethod.POST) public @ResponseBody void uploadImage(final @RequestBody ImageDTO image) 

Answer 2

And faced with a similar situation, and that's what I came up with. Both are not so clean, but they work just fine. You need to send the client a multi-page request :

Note. The data type of the variable to store the file is InputStream . You must modify it accordingly.

• This is useful in cases where you do not know the number of files that you receive a request from you.

   // imports import org.apache.commons.fileupload.servlet.ServletFileUpload; import org.apache.commons.fileupload.FileItem; import org.apache.commons.fileupload.disk.DiskFileItemFactory; // code flow // HttpServletRequest request final FileItemFactory factory = new DiskFileItemFactory(); final ServletFileUpload fileUpload = new ServletFileUpload(factory); List items = null; private Map<String, InputStream> fileMap = new HashMap<String, InputStream>(); if (ServletFileUpload.isMultipartContent(request)) { // get the request content and iterate through items = fileUpload.parseRequest(request); if (items != null) { final Iterator iter = items.iterator(); while (iter.hasNext()) { final FileItem item = (FileItem) iter.next(); final String fieldName = item.getFieldName(); final String fieldValue = item.getString(); // this is for non-file fields if (item.isFormField()) { switch (fieldName) { case "imageId" : // set inside your DTO field break; // do it for other fields } } else { // set the image in DTO field } } } } 

• In this case, you will have to deal with a fixed number of field shapes. I implemented the ReST method as follows:

   @Path("/upload") @POST @Consumes(MediaType.MULTIPART_FORM_DATA) public ResponseDTO upload(FormDataMultiPart multiPartData) { // non-file fields final String imageId = multiPartData.getField("imageId").getValue(); // for file field final FormDataBodyPart imagePart = multiPartData.getField("image"); final ContentDisposition imageDetails= imagePart.getContentDisposition(); final InputStream imageDoc = imagePart.getValueAs(InputStream.class); // set the retrieved content in DTO } 

Answer 3

I had the same result - NULL in all DTO members until I entered the @ModelAttribute annotation. Now everything works fine, here is the working code:

Controller Method :

 @RequestMapping(value = "/save", method = RequestMethod.POST, consumes = { "multipart/form-data" }) public void create(@Valid @ModelAttribute("entryForm") final EntryDTO entryDTO, final BindingResult validationResult) throws FormValidationError { validate(entryDTO, validationResult); entryService.save(entryDTO); } 

DTO

 public class EntryDTO { private String phrase; private String translation; private MultipartFile imageFile; } 

The form

 <form method="post" name="entryForm" action="http://localhost:8080/save" enctype="multipart/form-data"> <p><input type="text" name="phrase" value="test"/> phrase</p> <p><input type="text" name="translation" value=""/> translation</p> <p><input type="file" name="imageFile"/></p> <p><input type="submit"/></p> </form> 

Please note that the form is called "entryForm" and, accordingly, @ModelAttribute ("entryForm").