As described in Section 36.1, “RestTemplate Customization”, you can use a RestTemplateCustomizer with RestTemplateBuilder to build a customized RestTemplate. This is the recommended approach for creating a RestTemplate configured to use a proxy.

The exact details of the proxy configuration depend on the underlying client request factory that is being used. The following example configures HttpComponentsClientRequestFactory with an HttpClient that uses 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));
	}

}

When Reactor Netty is on the classpath a Reactor Netty-based WebClient is auto-configured. To customize the client’s handling of network connections, provide a ClientHttpConnector bean. The following example configures a 60 second read timeout and adds a ReadTimeoutHandler:

@Bean
ClientHttpConnector clientHttpConnector(ReactorResourceFactory resourceFactory) {
	TcpClient tcpClient = TcpClient.create(resourceFactory.getConnectionProvider())
			.runOn(resourceFactory.getLoopResources()).option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 60000)
			.doOnConnected((connection) -> connection.addHandlerLast(new ReadTimeoutHandler(60)));
	return new ReactorClientHttpConnector(HttpClient.from(tcpClient));
}

	Tip
	Note the use of ReactorResourceFactory for the connection provider and event loop resources. This ensures efficient sharing of resources for the server receiving requests and the client making requests.