How do I set a proxy for HttpClient?

In this example you will see how to configure proxy when using the Apache Commons HttpClient library.

package org.kodejava.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("https://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();
        }
    }
}

Maven Dependencies

<dependency>
    <groupId>commons-httpclient</groupId>
    <artifactId>commons-httpclient</artifactId>
    <version>3.1</version>
</dependency>

Maven Central

How do I perform HTTP GET method?

Below is an example using Commons HttpClient library to retrieve information from a website using HTTP GET method. The response will be returned as stream by the HttpMethod.getResponseBodyAsStream() method. If you want something simple you can get the response as string by using the HttpMethod.getResponseBodyAsString() method.

package org.kodejava.commons.httpclient;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpMethod;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.GetMethod;

import java.io.*;
import java.nio.charset.StandardCharsets;

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

        try {
            client.executeMethod(method);

            if (method.getStatusCode() == HttpStatus.SC_OK) {
                InputStream is = method.getResponseBodyAsStream();

                if (is != null) {
                    Writer writer = new StringWriter();
                    char[] buffer = new char[1024];
                    try {
                        Reader reader = new BufferedReader(new InputStreamReader(is,
                                StandardCharsets.UTF_8));
                        int length;
                        while ((length = reader.read(buffer)) != -1) {
                            writer.write(buffer, 0, length);
                        }
                    } finally {
                        is.close();
                    }
                    System.out.println("Response = " + writer);
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            method.releaseConnection();
        }
    }
}

Maven Dependencies

<dependency>
    <groupId>commons-httpclient</groupId>
    <artifactId>commons-httpclient</artifactId>
    <version>3.1</version>
</dependency>

Maven Central