localhost:8080/api/get/img/1/imageFileName.png

<img src="localhost:8080/api/get/img/1/imageFileName.png"/>

@GET
@Path("get/img/1")
public String getFile() {
    File file = Paths.get(".", "resources", "Mockup9EventsPageAsMember.png").normalize().toFile();
    return file.toString();
}