JAX-RS EE7 Upload File (Json Base64)

FileResource.java

package com.example;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Base64;
import java.util.UUID;

import javax.json.JsonObject;
import javax.ws.rs.Consumes;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.ResponseBuilder;
import javax.ws.rs.core.UriBuilder;
import javax.ws.rs.core.UriInfo;

@Path("file")
public class FileResource {
	
	final static String FILES_PATH = "/tmp";
	
	@GET
	@Path("ping")
	public String ping() {
		return "ping " + System.currentTimeMillis();
	}

    @POST
    @Path("upload")
    @Consumes(MediaType.APPLICATION_JSON)
    public Response receiveJSON(JsonObject json, @Context UriInfo uriInfo) 
    throws IOException {
        String id = convertFile(json.getString("file"));
      //String fileName = json.getString("file_name");
      //String mimeType = json.getString("mime_type");
        
        UriBuilder builder = uriInfo.getAbsolutePathBuilder();
        builder.path(id);
        return Response.created(builder.build()).build();
        
        // http://localhost:8080/helloworld-ee7/api/file/upload/5e774c4e-ae55-4291-a302-74396e29d842
    }

    //Convert a Base64 string and create a file
    private String convertFile(String dataBase64) 
    throws IOException{
        byte[] bytes = Base64.getDecoder().decode(dataBase64);
        String uuid = UUID.randomUUID().toString();
        File file = new File(FILES_PATH + File.separator + uuid);
        
        try (FileOutputStream fos = new FileOutputStream(file)) {
	        fos.write(bytes);
	        fos.flush();
        }
        
        return uuid;
    }
    
	@GET
	@Path("/upload/{uuid}")
	@Produces("application/pdf")
	public Response getFile(@PathParam("uuid") String uuid) {

		File file = new File(FILES_PATH + File.separator + uuid);

		ResponseBuilder response = Response.ok((Object) file);
		response.header("Content-Disposition",
				"attachment; filename=" + "document.pdf");
		return response.build();
	}    

}