Target server failed to respond exception with htmlunit and tor
HttpMethodRetryHandler myretryhandler = new HttpMethodRetryHandler() {
    public boolean retryMethod(
        final HttpMethod method,
        final IOException exception,
        int executionCount) {
        if (executionCount >= 5) {
            // Do not retry if over max retry count
            return false;
        }
        if (exception instanceof NoHttpResponseException) {
            // Retry if the server dropped connection on us
            return true;
        }
        if (!method.isRequestSent()) {
        // Retry if the request has not been sent fully or
        // if it's OK to retry methods that have been sent
        return true;
    }
    // otherwise do not retry
    return false;
    }
};

GetMethod httpget = new GetMethod("http://www.whatever.com/");
httpget.getParams().
setParameter(HttpMethodParams.RETRY_HANDLER, myretryhandler);
try {
    client.executeMethod(httpget);
    System.out.println(httpget.getStatusLine().toString());
} finally {
    httpget.releaseConnection();
}

WebClient client = new WebClient(BrowserVersion.FIREFOX_3_6);
client.setTimeout(60000);
client.setRedirectEnabled(true);
client.setJavaScriptEnabled(true);
client.setThrowExceptionOnFailingStatusCode(false);
client.setThrowExceptionOnScriptError(false);
client.setCssEnabled(false);
client.setUseInsecureSSL(true);

    HtmlPage page = null;
    try {
        page = client.getPage("http://www.whatever.com");
    } catch (Exception e) {
        // TODO Auto-generated catch block
    }
    if (page.getWebResponse().getStatusCode() == 404) {
        System.out.println("Page not found");
    }

    // Post a request
    WebRequest request = new WebRequest(new URL("http://www.whatever.com/post_url"));
    request.setHttpMethod(HttpMethod.POST);
    List<NameValuePair> params = new ArrayList<NameValuePair>();
    params.add(new NameValuePair("login", userLogin));
    params.add(new NameValuePair("pass", userPassword));
    request.setRequestParameters(params);

    page = client.getPage(request);