How do I set the proxy to be used by the JVM

Question

Many times, a Java app needs to connect to the Internet. The most common example happens when it is reading an XML file and needs to download its schema.

I am behind a proxy server. How do I set my JVM to use the proxy ?

Answer 1

You can set those flags programmatically this way:

if (needsProxy()) {
    System.setProperty("http.proxyHost",getProxyHost());
    System.setProperty("http.proxyPort",getProxyPort());
} else {
    System.setProperty("http.proxyHost","");
    System.setProperty("http.proxyPort","");
}

Just return the right values from the methods needsProxy(), getProxyHost() and getProxyPort() and you can call this code snippet whenever you want.

Answer 2

Recently I've discovered the way to allow JVM to use browser proxy settings. What you need to do is to add ${java.home}/lib/deploy.jar to your project and to init the library like the following:

import com.sun.deploy.net.proxy.DeployProxySelector;
import com.sun.deploy.services.PlatformType;
import com.sun.deploy.services.ServiceManager;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public abstract class ExtendedProxyManager {

    private static final Log logger = LogFactory.getLog(ExtendedProxyManager.class);

    /**
     * After calling this method, proxy settings can be magically retrieved from default browser settings.
     */
    public static boolean init() {
        logger.debug("Init started");

        // Initialization code was taken from com.sun.deploy.ClientContainer:
        ServiceManager
                .setService(System.getProperty("os.name").toLowerCase().indexOf("windows") != -1 ? PlatformType.STANDALONE_TIGER_WIN32
                        : PlatformType.STANDALONE_TIGER_UNIX);

        try {
            // This will call ProxySelector.setDefault():
            DeployProxySelector.reset();
        } catch (Throwable throwable) {
            logger.error("Unable to initialize extended dynamic browser proxy settings support.", throwable);

            return false;
        }

        return true;
    }
}

Afterwards the proxy settings are available to Java API via java.net.ProxySelector.

The only problem with this approach is that you need to start JVM with deploy.jar in bootclasspath e.g. java -Xbootclasspath/a:"%JAVA_HOME%\jre\lib\deploy.jar" -jar my.jar. If somebody knows how to overcome this limitation, let me know.

Answer 3

You can set some properties about the proxy server as jvm parameters

-Dhttp.proxyPort=8080, proxyHost, etc.

but if you need pass through an authenticating proxy, you need an authenticator like this example:

ProxyAuthenticator.java

import java.net.*;
import java.io.*;

public class ProxyAuthenticator extends Authenticator {

    private String userName, password;

    protected PasswordAuthentication getPasswordAuthentication() {
        return new PasswordAuthentication(userName, password.toCharArray());
    }

    public ProxyAuthenticator(String userName, String password) {
        this.userName = userName;
        this.password = password;
    }
}

Example.java

    import java.net.Authenticator;
    import ProxyAuthenticator;

public class Example {

    public static void main(String[] args) {
        String username = System.getProperty("proxy.authentication.username");
        String password = System.getProperty("proxy.authentication.password");

                if (username != null && !username.equals("")) {
            Authenticator.setDefault(new ProxyAuthenticator(username, password));
        }

                // here your JVM will be authenticated

    }
}

Based on this reply: http://mail-archives.apache.org/mod_mbox/jakarta-jmeter-user/200208.mbox/%3C494FD350388AD511A9DD00025530F33102F1DC2C@MMSX006%3E

Answer 4

This is a minor update, but since Java 7, proxy connections can now be created programmatically rather than through system properties. This may be useful if:

1. Proxy needs to be dynamically rotated during the program's runtime
2. Multiple parallel proxies need to be used
3. Or just make your code cleaner :)

Here's a contrived example in groovy:

// proxy configuration read from file resource under "proxyFileName"
String proxyFileName = "proxy.txt"
String proxyPort = "1234"
String url = "http://www.promised.land"
File testProxyFile = new File(proxyFileName)
URLConnection connection

if (!testProxyFile.exists()) {

    logger.debug "proxyFileName doesn't exist.  Bypassing connection via proxy."
    connection = url.toURL().openConnection()

} else {
    String proxyAddress = testProxyFile.text
    connection = url.toURL().openConnection(new Proxy(Proxy.Type.HTTP, new InetSocketAddress(proxyAddress, proxyPort)))
}

try {
    connection.connect()
}
catch (Exception e) {
    logger.error e.printStackTrace()
}

Full Reference: http://docs.oracle.com/javase/7/docs/technotes/guides/net/proxies.html

Answer 5

As is pointed out in other answers, if you need to use Authenticated proxies, there's no reliable way to do this purely using command-line variables - which is annoying if you're using someone else's application and don't want to mess with the source code.

Will Iverson makes the helpful suggestion over at Using HttpProxy to connect to a host with preemtive authentication to use a Proxy-management tool such as Proxifier ( http://www.proxifier.com/ for Mac OS X and Windows) to handle this.

For example with Proxifier you can set it up to only intercept java commands to be managed and redirected through its (authenticated) proxy. You're going to want to set the proxyHost and proxyPort values to blank in this case though, e.g. pass in -Dhttp.proxyHost= -Dhttp.proxyPort= to your java commands.

Answer 6

I think configuring WINHTTP will also work.

Many programs including Windows Updates are having problems behind proxy. By setting up WINHTTP will always fix this kind of problems