1. HTTP Clients
Spring Boot offers a number of starters that work with HTTP clients. This section answers questions related to using them.
1.1. Configure RestTemplate to Use a Proxy
As described in boot-features-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));
}
}1.2. Configure the TcpClient used by a Reactor Netty-based WebClient
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 connect 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));
}
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.
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