POP3Client (Apache Commons Net 3.6 API)

java.lang.Object
- org.apache.commons.net.SocketClient
- - org.apache.commons.net.pop3.POP3
  - - org.apache.commons.net.pop3.POP3Client

Direct Known Subclasses:

POP3SClient
```
public class POP3Client
extends POP3
```
The POP3Client class implements the client side of the Internet POP3 Protocol defined in RFC 1939. All commands are supported, including the APOP command which requires MD5 encryption. See RFC 1939 for more details on the POP3 protocol.
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:
POP3MessageInfo, DotTerminatedMessageReader, MalformedServerReplyException

Field Summary
- Fields inherited from class org.apache.commons.net.pop3.POP3
  _commandSupport_, AUTHORIZATION_STATE, DEFAULT_PORT, DISCONNECTED_STATE, TRANSACTION_STATE, UPDATE_STATE
- Fields inherited from class org.apache.commons.net.SocketClient
  _defaultPort_, _hostname_, _input_, _output_, _serverSocketFactory_, _socket_, _socketFactory_, _timeout_, connectTimeout, NETASCII_EOL

Constructor Summary

Constructors
Constructor and Description

POP3Client()

Constructors
Constructor and Description
`POP3Client()`

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`capa()` Send a CAPA command to the POP3 server.
`boolean`	`deleteMessage(int messageId)` Delete a message from the POP3 server.
`POP3MessageInfo`	`listMessage(int messageId)` List an individual message.
`POP3MessageInfo[]`	`listMessages()` List all messages.
`POP3MessageInfo`	`listUniqueIdentifier(int messageId)` List the unique identifier for a message.
`POP3MessageInfo[]`	`listUniqueIdentifiers()` List the unique identifiers for all messages.
`boolean`	`login(String username, String password)` Login to the POP3 server with the given username and password.
`boolean`	`login(String username, String timestamp, String secret)` Login to the POP3 server with the given username and authentication information.
`boolean`	`logout()` Logout of the POP3 server.
`boolean`	`noop()` Send a NOOP command to the POP3 server.
`boolean`	`reset()` Reset the POP3 session.
`Reader`	`retrieveMessage(int messageId)` Retrieve a message from the POP3 server.
`Reader`	`retrieveMessageTop(int messageId, int numLines)` Retrieve only the specified top number of lines of a message from the POP3 server.
`POP3MessageInfo`	`status()` Get the mailbox status.

Methods inherited from class org.apache.commons.net.pop3.POP3
_connectAction_, disconnect, getAdditionalReply, getCommandSupport, getReplyString, getReplyStrings, getState, removeProtocolCommandistener, sendCommand, sendCommand, sendCommand, sendCommand, setState

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - POP3Client
```
public POP3Client()
```
- Method Detail
  - capa
```
public boolean capa()
             throws IOException
```
    Send a CAPA command to the POP3 server.
    
    Returns:
    True if the command was successful, false if not.
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of sending the CAPA command.
    Since:
    
    3.1 (was previously in ExtendedPOP3Client)
  - login
```
public boolean login(String username,
            String password)
              throws IOException
```
    Login to the POP3 server with the given username and password. You must first connect to the server with connect before attempting to login. A login attempt is only valid if the client is in the AUTHORIZATION_STATE . After logging in, the client enters the TRANSACTION_STATE .
    
    Parameters:
    username - The account name being logged in to.
    password - The plain text password of the account.
    
    Returns:
    True if the login attempt was successful, false if not.
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of logging in.
  - login
```
public boolean login(String username,
            String timestamp,
            String secret)
              throws IOException,
                     NoSuchAlgorithmException
```
    Login to the POP3 server with the given username and authentication information. Use this method when connecting to a server requiring authentication using the APOP command. Because the timestamp produced in the greeting banner varies from server to server, it is not possible to consistently extract the information. Therefore, after connecting to the server, you must call getReplyString and parse out the timestamp information yourself.
    You must first connect to the server with connect before attempting to login. A login attempt is only valid if the client is in the AUTHORIZATION_STATE . After logging in, the client enters the TRANSACTION_STATE . After connecting, you must parse out the server specific information to use as a timestamp, and pass that information to this method. The secret is a shared secret known to you and the server. See RFC 1939 for more details regarding the APOP command.
    
    Parameters:
    username - The account name being logged in to.
    timestamp - The timestamp string to combine with the secret.
    secret - The shared secret which produces the MD5 digest when combined with the timestamp.
    
    Returns:
    True if the login attempt was successful, false if not.
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of logging in.
    
    NoSuchAlgorithmException - If the MD5 encryption algorithm cannot be instantiated by the Java runtime system.
  - logout
```
public boolean logout()
               throws IOException
```
    Logout of the POP3 server. To fully disconnect from the server you must call disconnect . A logout attempt is valid in any state. If the client is in the TRANSACTION_STATE , it enters the UPDATE_STATE on a successful logout.
    
    Returns:
    True if the logout attempt was successful, false if not.
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of logging out.
  - noop
```
public boolean noop()
             throws IOException
```
    Send a NOOP command to the POP3 server. This is useful for keeping a connection alive since most POP3 servers will timeout after 10 minutes of inactivity. A noop attempt will only succeed if the client is in the TRANSACTION_STATE .
    
    Returns:
    True if the noop attempt was successful, false if not.
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of sending the NOOP command.
  - deleteMessage
```
public boolean deleteMessage(int messageId)
                      throws IOException
```
    Delete a message from the POP3 server. The message is only marked for deletion by the server. If you decide to unmark the message, you must issuse a reset command. Messages marked for deletion are only deleted by the server on logout . A delete attempt can only succeed if the client is in the TRANSACTION_STATE .
    
    Parameters:
    messageId - The message number to delete.
    
    Returns:
    True if the deletion attempt was successful, false if not.
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of sending the delete command.
  - reset
```
public boolean reset()
              throws IOException
```
    Reset the POP3 session. This is useful for undoing any message deletions that may have been performed. A reset attempt can only succeed if the client is in the TRANSACTION_STATE .
    
    Returns:
    True if the reset attempt was successful, false if not.
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of sending the reset command.
  - status
```
public POP3MessageInfo status()
                       throws IOException
```
    Get the mailbox status. A status attempt can only succeed if the client is in the TRANSACTION_STATE . Returns a POP3MessageInfo instance containing the number of messages in the mailbox and the total size of the messages in bytes. Returns null if the status the attempt fails.
    
    Returns:
    A POP3MessageInfo instance containing the number of messages in the mailbox and the total size of the messages in bytes. Returns null if the status the attempt fails.
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of sending the status command.
  - listMessage
```
public POP3MessageInfo listMessage(int messageId)
                            throws IOException
```
    List an individual message. A list attempt can only succeed if the client is in the TRANSACTION_STATE . Returns a POP3MessageInfo instance containing the number of the listed message and the size of the message in bytes. Returns null if the list attempt fails (e.g., if the specified message number does not exist).
    
    Parameters:
    messageId - The number of the message list.
    
    Returns:
    A POP3MessageInfo instance containing the number of the listed message and the size of the message in bytes. Returns null if the list attempt fails.
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of sending the list command.
  - listMessages
```
public POP3MessageInfo[] listMessages()
                               throws IOException
```
    List all messages. A list attempt can only succeed if the client is in the TRANSACTION_STATE . Returns an array of POP3MessageInfo instances, each containing the number of a message and its size in bytes. If there are no messages, this method returns a zero length array. If the list attempt fails, it returns null.
    
    Returns:
    An array of POP3MessageInfo instances representing all messages in the order they appear in the mailbox, each containing the number of a message and its size in bytes. If there are no messages, this method returns a zero length array. If the list attempt fails, it returns null.
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of sending the list command.
  - listUniqueIdentifier
```
public POP3MessageInfo listUniqueIdentifier(int messageId)
                                     throws IOException
```
    List the unique identifier for a message. A list attempt can only succeed if the client is in the TRANSACTION_STATE . Returns a POP3MessageInfo instance containing the number of the listed message and the unique identifier for that message. Returns null if the list attempt fails (e.g., if the specified message number does not exist).
    
    Parameters:
    messageId - The number of the message list.
    
    Returns:
    A POP3MessageInfo instance containing the number of the listed message and the unique identifier for that message. Returns null if the list attempt fails.
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of sending the list unique identifier command.
  - listUniqueIdentifiers
```
public POP3MessageInfo[] listUniqueIdentifiers()
                                        throws IOException
```
    List the unique identifiers for all messages. A list attempt can only succeed if the client is in the TRANSACTION_STATE . Returns an array of POP3MessageInfo instances, each containing the number of a message and its unique identifier. If there are no messages, this method returns a zero length array. If the list attempt fails, it returns null.
    
    Returns:
    An array of POP3MessageInfo instances representing all messages in the order they appear in the mailbox, each containing the number of a message and its unique identifier If there are no messages, this method returns a zero length array. If the list attempt fails, it returns null.
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of sending the list unique identifier command.
  - retrieveMessage
```
public Reader retrieveMessage(int messageId)
                       throws IOException
```
    Retrieve a message from the POP3 server. A retrieve message attempt can only succeed if the client is in the TRANSACTION_STATE
    You must not issue any commands to the POP3 server (i.e., call any other methods) until you finish reading the message from the returned BufferedReader instance. The POP3 protocol uses the same stream for issuing commands as it does for returning results. Therefore the returned BufferedReader actually reads directly from the POP3 connection. After the end of message has been reached, new commands can be executed and their replies read. If you do not follow these requirements, your program will not work properly.
    
    Parameters:
    messageId - The number of the message to fetch.
    
    Returns:
    A DotTerminatedMessageReader instance from which the entire message can be read. This can safely be cast to a BufferedReader in order to use the BufferedReader#readLine() method. Returns null if the retrieval attempt fails (e.g., if the specified message number does not exist).
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of sending the retrieve message command.
  - retrieveMessageTop
```
public Reader retrieveMessageTop(int messageId,
                        int numLines)
                          throws IOException
```
    Retrieve only the specified top number of lines of a message from the POP3 server. A retrieve top lines attempt can only succeed if the client is in the TRANSACTION_STATE
    You must not issue any commands to the POP3 server (i.e., call any other methods) until you finish reading the message from the returned BufferedReader instance. The POP3 protocol uses the same stream for issuing commands as it does for returning results. Therefore the returned BufferedReader actually reads directly from the POP3 connection. After the end of message has been reached, new commands can be executed and their replies read. If you do not follow these requirements, your program will not work properly.
    
    Parameters:
    messageId - The number of the message to fetch.
    numLines - The top number of lines to fetch. This must be >= 0.
    
    Returns:
    A DotTerminatedMessageReader instance from which the specified top number of lines of the message can be read. This can safely be cast to a BufferedReader in order to use the BufferedReader#readLine() method. Returns null if the retrieval attempt fails (e.g., if the specified message number does not exist).
    
    Throws:
    
    IOException - If a network I/O error occurs in the process of sending the top command.

Class POP3Client

Field Summary

Fields inherited from class org.apache.commons.net.pop3.POP3

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

Constructor Summary

Method Summary

Methods inherited from class org.apache.commons.net.pop3.POP3

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

Methods inherited from class java.lang.Object

Constructor Detail

POP3Client

Method Detail

capa

login

login

logout

noop

deleteMessage

reset

status

listMessage

listMessages

listUniqueIdentifier

listUniqueIdentifiers

retrieveMessage

retrieveMessageTop