How to configure a proxy in Maven settings?

When we work behind a proxy server we need to configure Maven to be able to connect to the internet. To enable proxy we can configure Maven settings.xml file, either in ${M2_HOME}/conf/settings.xml or ${user.home}/.m2/settings.xml file.

<?xml version="1.0" encoding="UTF-8"?>
<settings>
    .
    .
    <proxies>
        <proxy>
            <id>my-proxy</id>
            <active>true</active>
            <protocol>http</protocol>
            <host>proxy.example.org</host>
            <port>8080</port>
            <username>username</username>
            <password>password</password>
            <nonProxyHosts>*.example.org|*.example.com</nonProxyHosts>
        </proxy>
    </proxies>
    .
    .
</settings>

The <proxy> element in the configuration above contains the information about the proxy server. These include information about the host, port, username and password. Set these elements to match your proxy server configuration.

How do I setting a proxy for HttpClient?

In this example you will see how to configure proxy for the HttpClient.

package org.kodejava.example.commons.httpclient;

import org.apache.commons.httpclient.Credentials;
import org.apache.commons.httpclient.HostConfiguration;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpMethod;
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 java.io.IOException;

public class HttpGetProxy {
    private static final String PROXY_HOST = "proxy.host.com";
    private static final int PROXY_PORT = 8080;

    public static void main(String[] args) {
        HttpClient client = new HttpClient();
        HttpMethod method = new GetMethod("http://www.kodejava.org");

        HostConfiguration config = client.getHostConfiguration();
        config.setProxy(PROXY_HOST, PROXY_PORT);

        String username = "guest";
        String password = "s3cr3t";
        Credentials credentials = new UsernamePasswordCredentials(username, password);
        AuthScope authScope = new AuthScope(PROXY_HOST, PROXY_PORT);

        client.getState().setProxyCredentials(authScope, credentials);

        try {
            client.executeMethod(method);

            if (method.getStatusCode() == HttpStatus.SC_OK) {
                String response = method.getResponseBodyAsString();
                System.out.println("Response = " + response);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            method.releaseConnection();
        }
    }
}