java.net.UnknownHostException, выброшенный из commons-httpclient-3.1.jar

Мне нужно использовать библиотеку commons-httpclient-3.1.jar, даже если она уже устарела.

Я пытаюсь выполнить простой HTTP GET с URL-адреса http://www.apache.org/ через прокси-сервер. адрес «10.100.1.44» с прокси-портом «8080», который не требует никаких учетных данных.

Ниже мой пример кода.

import java.io.IOException;
import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.UsernamePasswordCredentials;
import org.apache.commons.httpclient.auth.AuthScope;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.params.HttpMethodParams;

public class HttpClientTutorial {

    private static String url = "http://www.apache.org/";

    public static void main(String[] args) {
        // Create an instance of HttpClient.
        HttpClient client = new HttpClient();

        // Create a method instance.
        GetMethod method = new GetMethod(url);

        // Provide custom retry handler is necessary
        method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
                new DefaultHttpMethodRetryHandler(3, false));

        try {
            // setting proxy
            client.getParams().setAuthenticationPreemptive(true);
            client.getState().setProxyCredentials(
                    new AuthScope("10.100.1.44", 8080),
                    new UsernamePasswordCredentials("", ""));

            // Execute the method.
            int statusCode = client.executeMethod(method);

            if (statusCode != HttpStatus.SC_OK) {
                System.err.println("Method failed: " + method.getStatusLine());
            }

            // Read the response body.
            byte[] responseBody = method.getResponseBody();

            // Deal with the response.
            // Use caution: ensure correct character encoding and is not binary
            // data
            System.out.println(new String(responseBody));

        } catch (HttpException e) {
            System.err.println("Fatal protocol violation: " + e.getMessage());
            e.printStackTrace();
        } catch (IOException e) {
            System.err.println("Fatal transport error: " + e.getMessage());
            e.printStackTrace();
        } finally {
            // Release the connection.
            method.releaseConnection();
        }
    }
}

Однако, когда я запускаю код, я получаю исключение, которое

14 ส.ค. 2556 13:11:28 org.apache.commons.httpclient.HttpMethodDirector authenticateHost
WARNING: Required credentials not available for BASIC <any realm>@www.apache.org:80
14 ส.ค. 2556 13:11:28 org.apache.commons.httpclient.HttpMethodDirector authenticateHost
WARNING: Preemptive authentication requested but no default credentials available
Fatal transport error: www.apache.org
java.net.UnknownHostException: www.apache.org
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)
    at org.apache.commons.httpclient.protocol.DefaultProtocolSocketFactory.createSocket(DefaultProtocolSocketFactory.java:80)
    at org.apache.commons.httpclient.protocol.DefaultProtocolSocketFactory.createSocket(DefaultProtocolSocketFactory.java:122)
    at org.apache.commons.httpclient.HttpConnection.open(HttpConnection.java:707)
    at org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry(HttpMethodDirector.java:387)
    at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:171)
    at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:397)
    at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:323)
    at jenkins.plugin.assembla.api.HttpClientTutorial.main(HttpClientTutorial.java:38)

Может ли кто-нибудь сказать мне, что я сделал неправильно, поскольку я новичок в этой библиотеке HttpClient, однако мне нужно ее использовать, поскольку я не собираюсь использовать библиотеку HttpComponents?

Теперь я нашел решение этой проблемы. Пожалуйста, обратитесь к приведенному ниже коду.

import java.io.IOException;
import org.apache.commons.httpclient.Credentials;
import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.UsernamePasswordCredentials;
import org.apache.commons.httpclient.auth.AuthScope;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.params.HttpMethodParams;

public class HttpClientTutorial {

    private static String url = "http://www.apache.org/";

    public static void main(String[] args) {
        // Create an instance of HttpClient.
        HttpClient client = new HttpClient();

        // Create a method instance.
        GetMethod method = new GetMethod(url);

        // Provide custom retry handler is necessary
        method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
                new DefaultHttpMethodRetryHandler(3, false));

        try {
            // setting proxy
            client.getHostConfiguration().setProxy("10.100.1.44", 8080);

            // Execute the method.
            int statusCode = client.executeMethod(method);

            if (statusCode != HttpStatus.SC_OK) {
                System.err.println("Method failed: " + method.getStatusLine());
            }

            // Read the response body.
            byte[] responseBody = method.getResponseBody();

            // Deal with the response.
            // Use caution: ensure correct character encoding and is not binary
            // data
            System.out.println(new String(responseBody));

        } catch (HttpException e) {
            System.err.println("Fatal protocol violation: " + e.getMessage());
            e.printStackTrace();
        } catch (IOException e) {
            System.err.println("Fatal transport error: " + e.getMessage());
            e.printStackTrace();
        } finally {
            // Release the connection.
            method.releaseConnection();
        }
    }
}