# Class Authenticator

java.lang.Object
java.net.Authenticator

public abstract class Authenticator extends Object
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.

All methods that request authentication have a default implementation that fails.

Since:
  1.2
See Also:
  - `setDefault(java.net.Authenticator)`
  - `getPasswordAuthentication()`

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `static enum`
  `Authenticator.RequestorType`
  The type of the entity requesting authentication.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `Authenticator()`
  Constructor for subclasses to call.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static Authenticator`
  `getDefault()`
  Gets the default authenticator.
  `protected PasswordAuthentication`
  `getPasswordAuthentication()`
  Called when password authorization is needed.
  `protected final String`
  `getRequestingHost()`
  Gets the `hostname` of the site or proxy requesting authentication, or `null` if not available.
  `protected final int`
  `getRequestingPort()`
  Gets the port number for the requested connection.
  `protected final String`
  `getRequestingPrompt()`
  Gets the prompt string given by the requestor.
  `protected final String`
  `getRequestingProtocol()`
  Give the protocol that's requesting the connection.
  `protected final String`
  `getRequestingScheme()`
  Gets the scheme of the requestor (the HTTP scheme for an HTTP firewall, for example).
  `protected final InetAddress`
  `getRequestingSite()`
  Gets the `InetAddress` of the site requesting authorization, or `null` if not available.
  `protected URL`
  `getRequestingURL()`
  Returns the URL that resulted in this request for authentication.
  `protected Authenticator.RequestorType`
  `getRequestorType()`
  Returns whether the requestor is a Proxy or a Server.
  `static PasswordAuthentication`
  `requestPasswordAuthentication(String host, InetAddress addr, int port, String protocol, String prompt, String scheme)`
  Ask the authenticator that has been registered with the system for a password.
  `static PasswordAuthentication`
  `requestPasswordAuthentication(String host, InetAddress addr, int port, String protocol, String prompt, String scheme, URL url, Authenticator.RequestorType reqType)`
  Ask the authenticator that has been registered with the system for a password.
  `static PasswordAuthentication`
  `requestPasswordAuthentication(Authenticator authenticator, String host, InetAddress addr, int port, String protocol, String prompt, String scheme, URL url, Authenticator.RequestorType reqType)`
  Ask the given `authenticator` for a password.
  `static PasswordAuthentication`
  `requestPasswordAuthentication(InetAddress addr, int port, String protocol, String prompt, String scheme)`
  Ask the authenticator that has been registered with the system for a password.
  `PasswordAuthentication`
  `requestPasswordAuthenticationInstance(String host, InetAddress addr, int port, String protocol, String prompt, String scheme, URL url, Authenticator.RequestorType reqType)`
  Ask this authenticator for a password.
  `static void`
  `setDefault(Authenticator a)`
  Sets the authenticator that will be used by the networking code when a proxy or an HTTP server asks for authentication.

  ### Methods declared in class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### Authenticator

    public Authenticator()
    Constructor for subclasses to call.

- ## Method Details

  - ### setDefault

    public static void setDefault(Authenticator a)
    Sets the authenticator that will be used by the networking code when a proxy or an HTTP server asks for authentication.
    Parameters:
      `a` - The authenticator to be set. If a is `null` then any previously set authenticator is removed.

  - ### getDefault

    public static Authenticator getDefault()
    Gets the default authenticator.
    Returns:
      The default authenticator, if set, `null` otherwise.
    Since:
      9

  - ### requestPasswordAuthentication

    public static PasswordAuthentication requestPasswordAuthentication(InetAddress addr, int port, String protocol, String prompt, String scheme)
    Ask the authenticator that has been registered with the system for a password.
    Parameters:
      `addr` - The InetAddress of the site requesting authorization, or null if not known.
      `port` - the port for the requested connection
      `protocol` - The protocol that's requesting the connection (`getRequestingProtocol()`)
      `prompt` - A prompt string for the user
      `scheme` - The authentication scheme
    Returns:
      The username/password, or null if one can't be gotten.

  - ### requestPasswordAuthentication

    public static PasswordAuthentication requestPasswordAuthentication(String host, InetAddress addr, int port, String protocol, String prompt, String scheme)
    Ask the authenticator that has been registered with the system for a password. This is the preferred method for requesting a password because the hostname can be provided in cases where the InetAddress is not available.
    Parameters:
      `host` - The hostname of the site requesting authentication.
      `addr` - The InetAddress of the site requesting authentication, or null if not known.
      `port` - the port for the requested connection.
      `protocol` - The protocol that's requesting the connection (`getRequestingProtocol()`)
      `prompt` - A prompt string for the user which identifies the authentication realm.
      `scheme` - The authentication scheme
    Returns:
      The username/password, or null if one can't be gotten.
    Since:
      1.4

  - ### requestPasswordAuthentication

    public static PasswordAuthentication requestPasswordAuthentication(String host, InetAddress addr, int port, String protocol, String prompt, String scheme, URL url, Authenticator.RequestorType reqType)
    Ask the authenticator that has been registered with the system for a password.
    Parameters:
      `host` - The hostname of the site requesting authentication.
      `addr` - The InetAddress of the site requesting authorization, or null if not known.
      `port` - the port for the requested connection
      `protocol` - The protocol that's requesting the connection (`getRequestingProtocol()`)
      `prompt` - A prompt string for the user
      `scheme` - The authentication scheme
      `url` - The requesting URL that caused the authentication
      `reqType` - The type (server or proxy) of the entity requesting authentication.
    Returns:
      The username/password, or null if one can't be gotten.
    Since:
      1.5

  - ### requestPasswordAuthentication

    public static PasswordAuthentication requestPasswordAuthentication(Authenticator authenticator, String host, InetAddress addr, int port, String protocol, String prompt, String scheme, URL url, Authenticator.RequestorType reqType)
    Ask the given `authenticator` for a password. If the given `authenticator` is null, the authenticator, if any, that has been registered with the system using `setDefault` is used.
    Parameters:
      `authenticator` - the authenticator, or `null`.
      `host` - The hostname of the site requesting authentication.
      `addr` - The InetAddress of the site requesting authorization, or null if not known.
      `port` - the port for the requested connection
      `protocol` - The protocol that's requesting the connection (`getRequestingProtocol()`)
      `prompt` - A prompt string for the user
      `scheme` - The authentication scheme
      `url` - The requesting URL that caused the authentication
      `reqType` - The type (server or proxy) of the entity requesting authentication.
    Returns:
      The username/password, or `null` if one can't be gotten.
    Since:
      9

  - ### requestPasswordAuthenticationInstance

    public PasswordAuthentication requestPasswordAuthenticationInstance(String host, InetAddress addr, int port, String protocol, String prompt, String scheme, URL url, Authenticator.RequestorType reqType)
    Ask this authenticator for a password.
    Parameters:
      `host` - The hostname of the site requesting authentication.
      `addr` - The InetAddress of the site requesting authorization, or null if not known.
      `port` - the port for the requested connection
      `protocol` - The protocol that's requesting the connection (`getRequestingProtocol()`)
      `prompt` - A prompt string for the user
      `scheme` - The authentication scheme
      `url` - The requesting URL that caused the authentication
      `reqType` - The type (server or proxy) of the entity requesting authentication.
    Returns:
      The username/password, or null if one can't be gotten
    Since:
      9

  - ### getRequestingHost

    protected final String getRequestingHost()
    Gets the `hostname` of the site or proxy requesting authentication, or `null` if not available.
    Returns:
      the hostname of the connection requiring authentication, or null if it's not available.
    Since:
      1.4

  - ### getRequestingSite

    protected final InetAddress getRequestingSite()
    Gets the `InetAddress` of the site requesting authorization, or `null` if not available.
    Returns:
      the InetAddress of the site requesting authorization, or null if it's not available.

  - ### getRequestingPort

    protected final int getRequestingPort()
    Gets the port number for the requested connection.
    Returns:
      an `int` indicating the port for the requested connection.

  - ### getRequestingProtocol

    protected final String getRequestingProtocol()
    Give the protocol that's requesting the connection. Often this will be based on a URL, but in a future JDK it could be, for example, "SOCKS" for a password-protected SOCKS5 firewall.
    Returns:
      the protocol, optionally followed by "/version", where version is a version number.
    See Also:
      - `URL.getProtocol()`

  - ### getRequestingPrompt

    protected final String getRequestingPrompt()
    Gets the prompt string given by the requestor.
    Returns:
      the prompt string given by the requestor (realm for http requests)

  - ### getRequestingScheme

    protected final String getRequestingScheme()
    Gets the scheme of the requestor (the HTTP scheme for an HTTP firewall, for example).
    Returns:
      the scheme of the requestor

  - ### getPasswordAuthentication

    protected PasswordAuthentication getPasswordAuthentication()
    Called when password authorization is needed. Subclasses should override the default implementation, which returns null.
    Returns:
      The PasswordAuthentication collected from the user, or null if none is provided.

  - ### getRequestingURL

    protected URL getRequestingURL()
    Returns the URL that resulted in this request for authentication. If the corresponding request does not specify a URL, this method returns null.
    Returns:
      the requesting URL, or null if not available.
    Since:
      1.5

  - ### getRequestorType

    protected Authenticator.RequestorType getRequestorType()
    Returns whether the requestor is a Proxy or a Server.
    Returns:
      the authentication type of the requestor
    Since:
      1.5