How to set proxy host on HttpClient request in Java

Question

I want to set proxy before sending HttpClient request on a URL. As I am able to connect it curl command setting up the proxy but with Java code I am not able to do that.

Curl command:

**curl -I -x IP:80  URL**

Code change done in java file:

HttpClient client = new HttpClient();
System.getProperties().put("http.proxyHost", "someProxyURL");
System.getProperties().put("http.proxyPort", "someProxyPort");
EntityEnclosingMethod method = new PostMethod(url);
method.setRequestEntity(new StringRequestEntity(requestXML, "text/xml", "utf-8"));

With above code changes in my java file I am getting below error :

java.net.ConnectException: Connection refused (Connection refused)

Which shows that I am not able to connect that URL with the proxy I am trying to use to connect the URL.

Stratum

Which shows that there was no HTTP proxy running at the host:port you specified for it. – Semipalatinsk

@EJP i didn;t understand your question , yes proxy is not getting setup because of that we are getting connection refused error – Stratum

Deleted my answer, as I got the question wrong. – Singleton

Just to be clear: Are you talking about the Apache HttpClient? – Singleton

Which version do you use? As for the newest version you should be able to use the example given here: hc.apache.org/httpcomponents-client-ga/httpclient/examples/org/… or here: hc.apache.org/httpcomponents-client-ga/tutorial/html/… – Rajkot

Apache Tomcat/6.0.24 and Java version: 1.7.0_141 – Stratum

1107 search results for query java http client proxy 🙄 – Sthenic

Answer 1

I think this could be helpful:

HttpClient client = new HttpClient();

HostConfiguration config = client.getHostConfiguration();
config.setProxy("someProxyURL", "someProxyPort");

Credentials credentials = new UsernamePasswordCredentials("username", "password");
AuthScope authScope = new AuthScope("someProxyURL", "someProxyPort");
client.getState().setProxyCredentials(authScope, credentials);

EntityEnclosingMethod method = new PostMethod(url);
method.setRequestEntity(new StringRequestEntity(requestXML, "text/xml", "utf-8"));

Stroy

Which HttpClient version do you use? I can't even find the Class "HostConfiguration". – Entertaining

@刘同彬 3.1 I suppose. If you use 4.x version, look at the #4956144 – Stroy

What if I have a proxy without user and password? – Manhunt

@Stroy are there some distinct signatures that would allow a server to detect the request to be from HttpClient? – Leptorrhine

Answer 2

A full example is given in this tutorial: How do I setting a proxy for 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("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();
        }
    }
}

For this, you need to add a jar file: http://repo1.maven.org/maven2/commons-httpclient/commons-httpclient/3.1/commons-httpclient-3.1.jar

Complete Example of a Apache HttpClient 4.1, setting proxy can be found below

HttpHost proxy = new HttpHost("ip address",port number);
DefaultHttpClient httpclient = new DefaultHttpClient();
httpclient.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY,proxy);

HttpPost httpost = new HttpPost(url);
List<NameValuePair> nvps = new ArrayList<NameValuePair>();
nvps.add(new BasicNameValuePair("param name", param));
httpost.setEntity(new UrlEncodedFormEntity(nvps, HTTP.ISO_8859_1));
HttpResponse response = httpclient.execute(httpost);

HttpEntity entity = response.getEntity();
System.out.println("Request Handled?: " + response.getStatusLine());
InputStream in = entity.getContent();
httpclient.getConnectionManager().shutdown();

Resource Link: https://stackoverflow.com/a/4957144

For other version like 4.3 or 4.3+, you can go through this SO answer: Apache HttpClient 4.1 - Proxy Authentication

Wabash

Answer 3

Add maven dependency (4.2.X+):

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.3</version>
    <exclusions>
        <exclusion>
            <artifactId>commons-logging</artifactId>
            <groupId>commons-logging</groupId>
        </exclusion>
    </exclusions>
</dependency>

Use HttpClientBuilder and set flag useSystemProperties:

HttpClient client = HttpClientBuilder.create().useSystemProperties().build();

then you have two options at least:

Option A: Override arguments, i.e.

java -Djava.net.useSystemProxies=true 
     -Dhttp.proxyHost=PROXY_HOST
     -Dhttp.proxyPort=PROXY_PORT 
     -Dhttp.proxyUser=USERNAME
     -Dhttp.proxyPassword=PASSWORD
     -jar your-app.jar

Option B: Set up JVM (${JAVA_HOME}/lib/net.properties):

java.net.useSystemProxies=true
http.proxyHost=some-host
http.proxyPort=some-port

and run your application

Supporting

java.net.useSystemProxies means that the OS proxy setting will be used. What is the actual behaviour if you mix it with explicit proxy settings like http.proxyHost? I think it has no effect then. – Gadoid

Answer 4

With Java 17 it works like this:

HttpClient.newBuilder().proxy(ProxySelector.of(InetSocketAddress.createUnresolved("proxy.host.de", 3126))).build();

(3126 is the proxy port in my code snippet.)

Spectacular

Answer 5

System properties usually have to be set right upfront, which means either in the jvm startup with -Dhttp.proxyHost=some.host.com -Dhttp.proxyPort=8080, not forgetting the httpsProxyHost and ...Port)

Or which should work, too, in a static {} block.

I personally find the Jersey client implementation easier to work with, if you have the option to switch.

Beltane

Answer 6

You could use following to achieve the same tasks of having a proxy:

 HttpClient client = new HttpClient();
        PostMethod post = new PostMethod(url);
        post.addRequestHeader("Content-Type", "application/xml");

 String PROXY_HOST = "proxy.abc.com";
        int PROXY_PORT = 8080;
        HostConfiguration config = client.getHostConfiguration();
        config.setProxy(PROXY_HOST, PROXY_PORT);

int statusCode = client.executeMethod(post);
logger.debug("Status Code for Proxy Request:" + statusCode);

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