java.net.Authenticator

The class Authenticator represents an object that knows how to obtain authentication for a network connection. Usually, it will do this by prompting the user for information.

Applications use this class by overriding getPasswordAuthentication() in a sub-class. This method will typically use the various getXXX() accessor methods to get information about the entity requesting authentication. It must then acquire a username and password either by interacting with the user or through some other non-interactive means. The credentials are then returned as a PasswordAuthentication return value.

An instance of this concrete sub-class is then registered with the system by calling setDefault(Authenticator). When authentication is required, the system will invoke one of the requestPasswordAuthentication() methods which in turn will call the getPasswordAuthentication() method of the registered object.

HttpURLConnection supports proxy authentication through the Authenticator class. To enable authentication, your application subclasses Authenticator and defines the getPasswordAuthentication() method. A minimalist implementation is as follows:

public class SimpleAuthenticator extends Authenticator {
    private String username, password;

    public SimpleAuthenticator(String username,String password) {
        this.username = username;
        this.password = password;
    }

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

Next, it must register the authenticator through Authenticator.setDefault(). If we adapt the previous code sample to use Authenticator, it looks like this:

String url = "http://java.boot.by/";
String proxy = "proxy.mydomain.com";
String port = "8080";
String username = "mikalai";
String password = "pwd";

Authenticator.setDefault(new SimpleAuthenticator(username,password));

URL server = new URL(url);

Properties systemProperties = System.getProperties();
systemProperties.setProperty("http.proxyHost",proxy);
systemProperties.setProperty("http.proxyPort",port);

HttpURLConnection connection = (HttpURLConnection)server.openConnection();

connection.connect();
InputStream in = connection.getInputStream();
readResponse(in);