Without changing code, how to force httpClient to use proxy by environment variables or JVM arguments

Question

I found setting http.proxyHost and http.proxyPort is of no use to httpClient. How to force the httpClient to use proxy by environment variables or VM arguments or something like those without changing code?

Answer 1

in https://issues.apache.org/jira/browse/HTTPCLIENT-1128

SystemDefaultHttpClient was added to ver. 4.2

see http://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/org/apache/http/impl/client/SystemDefaultHttpClient.html

Answer 2

HTTP client (v 4.5.1 for my case) can use system proxy like this:

HttpClient httpClient = HttpClientBuilder.create().useSystemProperties().build(); //or  HttpClient httpClient = HttpClients.createSystem();