Package org.apache.commons.net.pop3

# Class POP3

java.lang.Object
org.apache.commons.net.SocketClient
org.apache.commons.net.pop3.POP3

Direct Known Subclasses:
  `POP3Client`

public class POP3 extends SocketClient
The POP3 class is not meant to be used by itself and is provided only so that you may easily implement your own POP3 client if you so desire. If you have no need to perform your own implementation, you should use `POP3Client`.

Rather than list it separately for each method, we mention here that every method communicating with the server and throwing an IOException can also throw a `MalformedServerReplyException` , which is a subclass of IOException. A MalformedServerReplyException will be thrown when the reply received from the server deviates enough from the protocol specification that it cannot be interpreted in a useful manner despite attempts to be as lenient as possible.

See Also:
  - `POP3Client`
  - `MalformedServerReplyException`

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected ProtocolCommandSupport`
  `_commandSupport_`
  A ProtocolCommandSupport object used to manage the registering of ProtocolCommandListeners and the firing of ProtocolCommandEvents.
  `static final int`
  `AUTHORIZATION_STATE`
  A constant representing the POP3 authorization state.
  `static final int`
  `DEFAULT_PORT`
  The default POP3 port.
  `static final int`
  `DISCONNECTED_STATE`
  A constant representing the state where the client is not yet connected to a POP3 server.
  `static final int`
  `TRANSACTION_STATE`
  A constant representing the POP3 transaction state.
  `static final int`
  `UPDATE_STATE`
  A constant representing the POP3 update state.

  ### Fields inherited from class org.apache.commons.net.SocketClient

  `_defaultPort_, _hostname_, _input_, _output_, _serverSocketFactory_, _socket_, _socketFactory_, _timeout_, connectTimeout, NETASCII_EOL, remoteInetSocketAddress`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `POP3()`
  The default POP3Client constructor.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected void`
  `_connectAction_()`
  Performs connection initialization and sets state to `AUTHORIZATION_STATE`.
  `void`
  `disconnect()`
  Disconnects the client from the server, and sets the state to `DISCONNECTED_STATE`.
  `void`
  `getAdditionalReply()`
  Gets the additional lines of a multi-line server reply.
  `protected ProtocolCommandSupport`
  `getCommandSupport()`
  Provide command support to super-class
  `String`
  `getReplyString()`
  Gets the reply to the last command sent to the server.
  `String[]`
  `getReplyStrings()`
  Gets an array of lines received as a reply to the last command sent to the server.
  `int`
  `getState()`
  Gets the current POP3 client state.
  `void`
  `removeProtocolCommandistener(ProtocolCommandListener listener)`
  Removes a ProtocolCommandListener.
  `int`
  `sendCommand(int command)`
  Sends a command with no arguments to the server and returns the reply code.
  `int`
  `sendCommand(int command, String args)`
  Sends a command an arguments to the server and returns the reply code.
  `int`
  `sendCommand(String command)`
  Sends a command with no arguments to the server and returns the reply code.
  `int`
  `sendCommand(String command, String args)`
  Sends a command an arguments to the server and returns the reply code.
  `void`
  `setState(int state)`
  Sets the internal POP3 state.

  ### Methods inherited from class org.apache.commons.net.SocketClient

  `addProtocolCommandListener, applySocketAttributes, checkOpenOutputStream, connect, connect, connect, connect, connect, connect, createCommandSupport, fireCommandSent, fireReplyReceived, getCharset, getCharsetName, getConnectTimeout, getDefaultPort, getDefaultTimeout, getHostAddress, getHostAddress, getKeepAlive, getLocalAddress, getLocalPort, getProxy, getReceiveBufferSize, getRemoteAddress, getRemoteInetSocketAddress, getRemotePort, getSendBufferSize, getServerSocketFactory, getSoLinger, getSoTimeout, getTcpNoDelay, isAvailable, isConnected, removeProtocolCommandListener, setCharset, setConnectTimeout, setDefaultPort, setDefaultTimeout, setKeepAlive, setProxy, setReceiveBufferSize, setSendBufferSize, setServerSocketFactory, setSocketFactory, setSoLinger, setSoTimeout, setTcpNoDelay, verifyRemote`

  ### Methods inherited from class java.lang.Object

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

- ## Field Details

  - ### DEFAULT_PORT

    public static final int DEFAULT_PORT
    The default POP3 port. Set to 110 according to RFC 1288.
    See Also:
      - Constant Field Values

  - ### DISCONNECTED_STATE

    public static final int DISCONNECTED_STATE
    A constant representing the state where the client is not yet connected to a POP3 server.
    See Also:
      - Constant Field Values

  - ### AUTHORIZATION_STATE

    public static final int AUTHORIZATION_STATE
    A constant representing the POP3 authorization state.
    See Also:
      - Constant Field Values

  - ### TRANSACTION_STATE

    public static final int TRANSACTION_STATE
    A constant representing the POP3 transaction state.
    See Also:
      - Constant Field Values

  - ### UPDATE_STATE

    public static final int UPDATE_STATE
    A constant representing the POP3 update state.
    See Also:
      - Constant Field Values

  - ### _commandSupport_

    protected ProtocolCommandSupport _commandSupport_
    A ProtocolCommandSupport object used to manage the registering of ProtocolCommandListeners and the firing of ProtocolCommandEvents.

- ## Constructor Details

  - ### POP3

    public POP3()
    The default POP3Client constructor. Initializes the state to `DISCONNECTED_STATE`.

- ## Method Details

  - ### _connectAction_

    protected void _connectAction_() throws IOException
    Performs connection initialization and sets state to `AUTHORIZATION_STATE`.
    Overrides:
      `_connectAction_` in class `SocketClient`
    Throws:
      `IOException` - (SocketException) if a problem occurs with the socket

  - ### disconnect

    public void disconnect() throws IOException
    Disconnects the client from the server, and sets the state to `DISCONNECTED_STATE`. The reply text information from the last issued command is voided to allow garbage collection of the memory used to store that information.
    Overrides:
      `disconnect` in class `SocketClient`
    Throws:
      `IOException` - If there is an error in disconnecting.

  - ### getAdditionalReply

    public void getAdditionalReply() throws IOException
    Gets the additional lines of a multi-line server reply.
    Throws:
      `IOException` - on error

  - ### getCommandSupport

    protected ProtocolCommandSupport getCommandSupport()
    Provide command support to super-class
    Overrides:
      `getCommandSupport` in class `SocketClient`
    Returns:
      the CommandSupport instance, may be `null`

  - ### getReplyString

    public String getReplyString()
    Gets the reply to the last command sent to the server. The value is a single string containing all the reply lines including newlines. If the reply is a single line, but its format ndicates it should be a multiline reply, then you must call `getAdditionalReply()` to fetch the rest of the reply, and then call `getReplyString` again. You only have to worry about this if you are implementing your own client using the `sendCommand` methods.
    Returns:
      The last server response.

  - ### getReplyStrings

    public String[] getReplyStrings()
    Gets an array of lines received as a reply to the last command sent to the server. The lines have end of lines truncated. If the reply is a single line, but its format ndicates it should be a multiline reply, then you must call `getAdditionalReply()` to fetch the rest of the reply, and then call `getReplyStrings` again. You only have to worry about this if you are implementing your own client using the `sendCommand` methods.
    Returns:
      The last server response.

  - ### getState

    public int getState()
    Gets the current POP3 client state.
    Returns:
      The current POP3 client state.

  - ### removeProtocolCommandistener

    public void removeProtocolCommandistener(ProtocolCommandListener listener)
    Removes a ProtocolCommandListener. Delegates this incorrectly named method - removeProtocolCommandistener (note the missing "L")- to the correct method `SocketClient.removeProtocolCommandListener(org.apache.commons.net.ProtocolCommandListener)`
    Parameters:
      `listener` - The ProtocolCommandListener to remove

  - ### sendCommand

    public int sendCommand(int command) throws IOException
    Sends a command with no arguments to the server and returns the reply code.
    Parameters:
      `command` - The POP3 command to send (one of the POP3Command constants).
    Returns:
      The server reply code (either `POP3Reply.OK`, `POP3Reply.ERROR` or `POP3Reply.OK_INT`).
    Throws:
      `IOException` - on error

  - ### sendCommand

    public int sendCommand(int command, String args) throws IOException
    Sends a command an arguments to the server and returns the reply code.
    Parameters:
      `command` - The POP3 command to send (one of the POP3Command constants).
      `args` - The command arguments.
    Returns:
      The server reply code (either `POP3Reply.OK`, `POP3Reply.ERROR` or `POP3Reply.OK_INT`).
    Throws:
      `IOException` - on error

  - ### sendCommand

    public int sendCommand(String command) throws IOException
    Sends a command with no arguments to the server and returns the reply code.
    Parameters:
      `command` - The POP3 command to send.
    Returns:
      The server reply code (either `POP3Reply.OK`, `POP3Reply.ERROR` or `POP3Reply.OK_INT`).
    Throws:
      `IOException` - on error

  - ### sendCommand

    public int sendCommand(String command, String args) throws IOException
    Sends a command an arguments to the server and returns the reply code.
    Parameters:
      `command` - The POP3 command to send.
      `args` - The command arguments.
    Returns:
      The server reply code (either `POP3Reply.OK`, `POP3Reply.ERROR` or `POP3Reply.OK_INT`).
    Throws:
      `IOException` - on error

  - ### setState

    public void setState(int state)
    Sets the internal POP3 state.
    Parameters:
      `state` - the new state. This must be one of the `_STATE` constants.