How to enable Spring Boot to connect to external API

Question

I'm developing a Spring Boot application behind a Proxy server. Now I need to connect to an external API but I didn't figure out yet what to configure in order to enable the application to connect to the outside API, I already tried to pass the proxy data with the program arguments and I already tried to configure the proxy in the Java Control Panel. How do I get the application to use the proxy in order to access the API?

Answer 1

You can use your custom RestTemplate, here in an exemple :

YourCustomRestTemplate.java :

class YourCustomRestTemplate implements RestTemplateCustomizer {

    @Override
    public void customize(RestTemplate restTemplate) {
        HttpHost proxy = new HttpHost(PROXY_SERVER_HOST, PROXY_SERVER_PORT);
        HttpClient httpClient = HttpClientBuilder.create()
            .setRoutePlanner(new DefaultProxyRoutePlanner(proxy) {
                @Override
                public HttpHost determineProxy(HttpHost target, HttpRequest request, HttpContext context) throws HttpException {
                    return super.determineProxy(target, request, context);
                }
            })
            .build();
        restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory(httpClient));
    }
}

When you want to build RestTemplate object to call the API :

RestTemplate restTemplate = new RestTemplateBuilder(new YourCustomRestTemplate()).build();

ResponseEntity<String> responseEntity = restTemplate.getForEntity("__URL__/get", String.class);