如何从 httpclient 连接获取底层 Socket？

Question

This question is worded the same way as another question on SO ( HttpClient: how do I obtain the underlying socket from an existing connection? ), but that question is actually about tunneling other protocols through HTTP(S) and thus the answer is quite a bit different.

What I'm trying to do is make an HTTPS connection, then find out the details of that connection. Java's SSLSocket class will give me what I need, but I need to be able to get a hold of the Socket itself in order to interrogate it.

Is there a way to get to the underlying Socket ? httpclient/httpcore has become a maze of factories and private/protected implementations of things, so it's really difficult to poke-around the API to figure out how to actually get things once they have been configured.

Answer 1

HttpClient intentionally makes it difficult to get hold of the underlying connection object and the socket it is bound to, primarily to ensure the connection state is consistent and persistent connections in the connection pool are safe to be re-used by another transaction.

However, one can get hold of the underlying connection from a response interceptor.

CloseableHttpClient httpclient = HttpClients.custom()
        .addInterceptorLast(new HttpResponseInterceptor() {
            @Override
            public void process(
                    final HttpResponse response,
                    final HttpContext context) throws HttpException, IOException {
                HttpClientContext clientContext = HttpClientContext.adapt(context);
                ManagedHttpClientConnection connection = clientContext.getConnection(ManagedHttpClientConnection.class);
                // Can be null if the response encloses no content
                if (connection != null) {
                    Socket socket = connection.getSocket();
                    System.out.println(socket);
                }

            }
        })
        .build();
try (CloseableHttpResponse response = httpclient.execute(new HttpGet("http://www.google.com/"))) {
    System.out.println(response.getStatusLine());
    EntityUtils.consume(response.getEntity());
}

Answer 2

I ended up using a somewhat different technique, but @oleg got me on the right track. Here's my one-time code:

HttpClientContext ctx = HttpClientContext.create();
HttpResponse response = getHttpClient().execute(method, ctx);

if(log.isDebugEnabled())
{
    ManagedHttpClientConnection connection = ctx.getConnection(ManagedHttpClientConnection.class);
    // Can be null if the response encloses no content
    if(null != connection)
    {
        Socket socket = connection.getSocket();
        if(socket instanceof SSLSocket)
        {
            SSLSocket sslSock = (SSLSocket)socket;
            log.debug("Connected to " + getEndpointURL()
                      + " using " + sslSock.getSession().getProtocol()
                      + " and suite " + sslSock.getSession().getCipherSuite());
        }
    }
}