Use system Proxy Settings

If you have a proxy configured on your local system. You can try to set the java.net.useSystemProxies (default is false) this property will try to apply the system properties.

-Djava.net.useSystemProxies=true
System.setProperty("java.net.useSystemProxies", "true");

Using Command Line JVM Settings

You can configure your server to use a HTTP Proxy server with JVM command line arguments. You can pass the following arguments either when you use a http or https proxy server.

// HTTP
-Dhttp.proxyHost=http://proxy.memorynotfound.com
-Dhttp.proxyPort=80

// HTTPS
-Dhttps.proxyHost=https://proxy.memorynotfound.com
-Dhttps.proxyPort=443

Passing arguments to Tomcat

Catalina.properties

Append following properties to the catalina.properties file in Tomcat: ${CATALINA_HOME}/conf/catalina.properties.

http.proxyHost=http://proxy.memorynotfound.com
http.proxyPort=80

Catalina.bat

Append following properties to the startup file in Tomcat:

• ${CATALINA_HOME}/bin/catalina.bat for windows
• ${CATALINA_HOME}/bin/catalina.sh for linux/mac

JAVA_OPTS="-Dhttp.proxyHost=http://proxy.memorynotfound.com -Dhttp.proxyPort=80"

Programatically set HTTP Proxy Settings

If you want you can also add proxy settings programmatically use the same properties but this time set them using System.setProperty();.

// HTTP
System.setProperty("http.proxyHost", "http://proxy.memorynotfound.com");
System.setProperty("http.proxyPort", "80");
System.setProperty("http.nonProxyHosts", "localhost|127.0.0.1");

// HTTPS
System.setProperty("https.proxyHost", "https://proxy.memorynotfound.com");
System.setProperty("https.proxyPort", "443");

Authenticating Proxy

Taking the above into account. Here is how you can Authenticate via a proxy. This initialisation code is typically executed at application startup. So make sure you register this authenticator before you make any HTTP Requests that require Proxy Authentication.

// settings proxy credentials
System.setProperty("http.proxyUser", "proxyUser");
System.setProperty("http.proxyPassword", "secret");

// Java ignores http.proxyUser. Here come's the workaround.
Authenticator.setDefault(new Authenticator() {
    @Override
    protected PasswordAuthentication getPasswordAuthentication() {
        if (getRequestorType() == RequestorType.PROXY) {
            String prot = getRequestingProtocol().toLowerCase();
            String host = System.getProperty(prot + ".proxyHost", "");
            String port = System.getProperty(prot + ".proxyPort", "80");
            String user = System.getProperty(prot + ".proxyUser", "");
            String password = System.getProperty(prot + ".proxyPassword", "");
            if (getRequestingHost().equalsIgnoreCase(host)) {
                if (Integer.parseInt(port) == getRequestingPort()) {
                    return new PasswordAuthentication(user, password.toCharArray());
                }
            }
        }
        return null;
    }
});

References