Apache HttpClient 4.3.5 set proxy

Question

It seems that I can specify the proxy when I construct new HttpClient with:

HttpHost proxy = new HttpHost("someproxy", 8080);
DefaultProxyRoutePlanner routePlanner = new DefaultProxyRoutePlanner(proxy);
CloseableHttpClient httpclient = HttpClients.custom()
    .setRoutePlanner(routePlanner)
    .build();

taken from http://hc.apache.org/httpcomponents-client-ga/tutorial/html/connmgmt.html#d5e475

Is it possible to modify existing client's proxy settings.

Solution

You can create your own implementation of HttpRoutePlanner that will allow change of the HttpHost.

public class DynamicProxyRoutePlanner implements HttpRoutePlanner {

    private DefaultProxyRoutePlanner defaultProxyRoutePlanner = null;

    public DynamicProxyRoutePlanner(HttpHost host){
        defaultProxyRoutePlanner = new DefaultProxyRoutePlanner(host);
    }

    public void setProxy(HttpHost host){
        defaultProxyRoutePlanner = new DefaultProxyRoutePlanner(host);
    }

    public HttpRoute determineRoute(HttpHost target, HttpRequest request, HttpContext context) {
        return defaultProxyRoutePlanner.determineRoute(target,request,context); 
    }
}

Then you can use this DynamicProxyRoutePlanner in your code

HttpHost proxy = new HttpHost("someproxy", 8080);
DynamicProxyRoutePlanner routePlanner = new DynamicProxyRoutePlanner(proxy);
CloseableHttpClient httpclient = HttpClients.custom()
    .setRoutePlanner(routePlanner)
    .build();

//Any time change the proxy 
routePlanner.setProxy(new HttpHost("someNewProxy", 9090));