Why do my RestTemple not connect to server?

I am working with Springboot and Java 8

I have following url, that works pretty fine with postman:

"http://localhost:8888/gc/goods/getAll"

Now I have tried to write an automated test:

    @Test
    public void getAllGoodsRequest()
    {
        RestTemplate restTemplate = new RestTemplate();
        Object test = restTemplate.getForObject("http://localhost:8888/gc/goods/getAll", Object.class);
    }

While Postman gives me all data back, I get following error from my test:

org.springframework.web.client.ResourceAccessException: I/O error on GET request for "http://localhost:8888/gc/goods/getAll": Connection refused: connect; nested exception is java.net.ConnectException: Connection refused: connect

How do I request the Data correctly during testing?

Thanks for help!