Sending images with AndroidAnnotations RestService

Question

What is the best way to send a file using the RestService? I have an image that I have to send to the server.

The API expects the following POST data:

image -> image I want to send
description -> text
title -> text

Can I just send an object with the needed values to achieve this or do I have to do it another way?

class NewImage {
    private Bitmap image;
    private String description;
    private String title;
}

Answer 1

You should use a multipart POST request:

Client:

@Rest(rootUrl = "your_url", converters = FormHttpMessageConverter.class)
public interface UploadClient extends RestClientHeaders {
    @Post("/Image/{id}")
    @RequiresHeader(HttpHeaders.CONTENT_TYPE)  
    String uploadImage(int id, MultiValueMap<String, Object> data);     
}

Usage:

MultiValueMap<String, Object> data = new LinkedMultiValueMap<>();

FileSystemResource image = new FileSystemResource("path_to_image");
String description = "description";
String title = "title";

data.put("image", image);
data.put("description", description);
data.put("title", title);

client.setHeader(HttpHeaders.CONTENT_TYPE, MediaType.MULTIPART_FORM_DATA_VALUE);

client.uploadImage(1, data);

I know this has some boilerplate, but it will be improved in the near future.

Reflect for the question in the comment:

You can create a class:

class ObjectSupportingFormHttpMessageConverter extends FormHttpMessageConverter {
    public ObjectSupportingFormHttpMessageConverter() {
        addPartConverter(new ObjectToStringHttpMessageConverter(new DefaultConversionService()));
    }
}

Then use it as a converter. This will convert your objects to text/plain parts. However, maybe it is better to serialize this complex structure into JSON instead of sending it in the multipart post.