33.1 RestTemplate customization

When a RestTemplateBuilder builds a RestTemplate it can be further customized using a RestTemplateCustomizer. Any RestTemplateCustomizer beans will be automatically added to the auto-configured RestTemplateBuilder. Furthermore, a new RestTemplateBuilder with additional customizers can be created by calling additionalCustomizers(RestTemplateCustomizer…​).

Here’s an example of a customizer that configures the use of a proxy for all hosts except 192.168.0.5:

static class ProxyCustomizer implements RestTemplateCustomizer {

    _@Override_
    public void customize(RestTemplate restTemplate) {
        HttpHost proxy = new HttpHost("proxy.example.com");
        HttpClient httpClient = HttpClientBuilder.create()
                .setRoutePlanner(new DefaultProxyRoutePlanner(proxy) {

                    _@Override_
                    public HttpHost determineProxy(HttpHost target,
                            HttpRequest request, HttpContext context)
                                    throws HttpException {
                        if (target.getHostName().equals("192.168.0.5")) {
                            return null;
                        }
                        return super.determineProxy(target, request, context);
                    }

                }).build();
        restTemplate.setRequestFactory(
                new HttpComponentsClientHttpRequestFactory(httpClient));
    }

}