Using Proxy with HttpComponentsClientHttpRequestFactory and RestTemplate

Question

Can some one guide me how can I configure HttpComponentsClientHttpRequestFactory to use proxy server.

All examples I have seen are using SimpleClientHttpRequestFactory.

Answer 1

If you do not mind using Apache Http Client it is not very complicated and there are 2 possibilities:

1. If single proxy for all targets is enough for you:

   HttpComponentsClientHttpRequestFactory clientHttpRequestFactory 
       = new HttpComponentsClientHttpRequestFactory(
           HttpClientBuilder.create()
                   .setProxy(new HttpHost("myproxy.com", 80, "http"))
                   .build());
   restTemplate = new RestTemplate(clientHttpRequestFactory);
   

2. Or if you want to use different proxies for different target URIs, schemas, etc. you can use HttpRoutePlanner with custom ProxySelector:

   HttpRoutePlanner routePlanner = new SystemDefaultRoutePlanner(new MyProxySelector());
   
   HttpComponentsClientHttpRequestFactory clientHttpRequestFactory 
       = new HttpComponentsClientHttpRequestFactory(
           HttpClientBuilder.create()
               .setRoutePlanner(routePlanner)
               .build());
   restTemplate = new RestTemplate(clientHttpRequestFactory);
   

   Example proxy selector: MyProxySelector.java:

   package hello;
   
   import java.io.IOException;
   import java.net.InetSocketAddress;
   import java.net.Proxy;
   import java.net.Proxy.Type;
   import java.net.ProxySelector;
   import java.net.SocketAddress;
   import java.net.URI;
   import java.util.ArrayList;
   import java.util.List;
   
   public class MyProxySelector extends ProxySelector {
   
       ProxySelector defaultproxySelector = ProxySelector.getDefault();
   
       ArrayList<Proxy> noProxy = new ArrayList<Proxy>();
       ArrayList<Proxy> secureProxy = new ArrayList<Proxy>();
       ArrayList<Proxy> sociaMediaProxy = new ArrayList<Proxy>();
   
       public MyProxySelector(){
   
           noProxy.add(Proxy.NO_PROXY);
   
           secureProxy.add(new Proxy(Type.HTTP, new InetSocketAddress(
               "secure.proxy.mycompany.com", 8080)));
   
           sociaMediaProxy.add(new Proxy(Type.HTTP, new InetSocketAddress(
                   "social-media.proxy.mycompany.com", 8080)));
       }
   
       @Override
       public List<Proxy> select(URI uri) {
   
           // No proxy for local company addresses.
           if ( uri.getHost().toLowerCase().endsWith("mycompany.com") ) {
               return noProxy ;
           }
   
           // Special proxy for social networks.
           String host = uri.getHost().toLowerCase();
           if (    host.endsWith("facebook.com") ||
                   host.endsWith("twitter.com") ||
                   host.endsWith("cfapps.io") ||               
                   host.endsWith("flickr.com") ) 
           {
               return sociaMediaProxy ;
           }
   
           // for https URIs use secureProxy
           if ( uri.getScheme().toLowerCase().equals("https") ){
               return secureProxy ;
           }
   
           if (defaultproxySelector != null) {
               return defaultproxySelector.select(uri);
           }
   
           return noProxy;
       }
   
       @Override
       public void connectFailed(URI arg0, SocketAddress arg1, IOException arg2) {
           // TODO Auto-generated method stub
       }
   }
   

Answer 2

Very simple way to let the HttpComponentsClientHttpRequestFactory use the standard java SystemProperties for proxy-stuff (see https://docs.oracle.com/javase/8/docs/technotes/guides/net/proxies.html)

is this:

        HttpRoutePlanner routePlanner = new SystemDefaultRoutePlanner(ProxySelector.getDefault());

    HttpClient httpClient = HttpClientBuilder
            .create()
            .setRoutePlanner(routePlanner)
            .build();
    restTemplate.setRequestFactory(
            new HttpComponentsClientHttpRequestFactory(httpClient));

That way, it even regards the nonProxyHosts setting.