Authenticator

Authenticator

java.net

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Java 1.2

This abstract class defines a customizable mechanism for requesting and performing password authentication when required in URL -based networking. The static setDefault( ) method establishes the systemwide Authenticator . An Authenticator implementation can obtain the required authentication information from the user however it wants (e.g., through a text- or a GUI-based interface). setDefault( ) can be called only once; subsequent calls are ignored. Calling setDefault( ) requires an appropriate NetPermission .

When an application or the Java runtime system requires password authentication (to read the contents of a specified URL , for example), it calls the static requestPasswordAuthentication( ) method, passing arguments that specify the host and port for which the password is required and a prompt that may be displayed to the user. This method looks up the default Authenticator for the system and calls its getPasswordAuthentication( ) method. Calling requestPasswordAuthentication( ) requires an appropriate NetPermission .

Authenticator is an abstract class; its default implementation of getPasswordAuthentication( ) always returns null . To create an Authenticator , you must override this method so that it prompts the user to enter a username and password and returns that information in the form of a PasswordAuthentication object. Your implementation of getPasswordAuthentication( ) may call the various getrequesting( ) methods to find out who is requesting the password and what the recommended user prompt is. Java 1.4 added a version of the static requestPasswordAuthentication( ) method that allows specification of the requesting hostname. A corresponding getrequestingHost( ) instance method was also added.

Java 5.0 adds yet another version of requestPasswordAuthentication( ) , and corresponding methods to query the URL that requires the password and the RequestorType of the request. RequestorType is a nested enum type that specifies whether the request comes from an HTTP server or a proxy server.

 public abstract class  Authenticator  {  // Public Constructors  public  Authenticator  ( );  // Nested Types   5.0  public enum  RequestorType  ;  // Public Class Methods  public static PasswordAuthentication  requestPasswordAuthentication  (InetAddress  addr  , int  port  , String  protocol  ,  String  prompt  , String  scheme  );  1.4  public static PasswordAuthentication  requestPasswordAuthentication  (String  host  , InetAddress  addr  , int  port  , String  protocol  ,  String  prompt  , String  scheme  );  5.0  public static PasswordAuthentication  requestPasswordAuthentication  (String  host  ,          InetAddress  addr  , int  port  , String  protocol  , String  prompt  ,          String  scheme  , URL  url  , Authenticator.RequestorType  reqType  );        public static void  setDefault  (Authenticator  a  );  synchronized   // Protected Instance Methods  protected PasswordAuthentication  getPasswordAuthentication  ( );  constant   1.4  protected final String  getRequestingHost  ( );      protected final int  getRequestingPort  ( );        protected final String  getRequestingPrompt  ( );        protected final String  getRequestingProtocol  ( );        protected final String  getRequestingScheme  ( );        protected final InetAddress  getRequestingSite  ( );  5.0  protected URL  getRequestingURL  ( );  5.0  protected Authenticator.RequestorType  getRequestorType  ( );   }