Upload file on Jersey

[Magador]

In your HTML form, you just need a form with a file input and a submit button:

<form method="post" action="path/to/servlet" enctype="multipart/form-data">
    <input type="file" required name="file"/>
    <input type="submit" />
</form>

Minimal HTML for single file upload.
Using Jersey.

@MultipartConfig(location = "path/to/file/directory", fileSizeThreshold = maxSizeOfFileOnDisk)
@Path("path/to/rest")
public class ImageResource {

    @Context
    HttpServletRequest req;

    @POST
    @Consumes(MediaType.MULTIPART_FORM_DATA)
    @Path("upload")
    public Response uploadImage(@FormDataParam("file") InputStream file, @FormDataParam("file") FormDataContentDisposition fileDisposition) {
        // Directory + Filename + Extension
        String filePath = this.getClass().getAnnotation(MultipartConfig.class).location() + File.separator +
                          <FILE_NAME> +
                          fileDisposition.getFileName().substring(fileDisposition.getFileName().indexOf('.') + 1);
        try {
            OutputStream os = new FileOutputStream(new File(filePath));
            int read = 0;
            byte[] bytes = new byte[4096];
            while ((read = file.read(bytes)) != -1)
                os.write(bytes, 0, read);
            os.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

This is the minimal required code for this to work.