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The source code

/*
 * Copyright 2001-2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.net.pop3;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.lang.StringBuffer;
import java.util.Enumeration;
import java.util.Vector;
import org.apache.commons.net.MalformedServerReplyException;
import org.apache.commons.net.ProtocolCommandListener;
import org.apache.commons.net.ProtocolCommandSupport;
import org.apache.commons.net.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. *

*

* @author Daniel F. Savarese * @see POP3Client * @see org.apache.commons.net.MalformedServerReplyException ***/ public class POP3 extends SocketClient { /*** The default POP3 port. Set to 110 according to RFC 1288. ***/ public static final int DEFAULT_PORT = 110; /*** * A constant representing the state where the client is not yet connected * to a POP3 server. ***/ public static final int DISCONNECTED_STATE = -1; /*** A constant representing the POP3 authorization state. ***/ public static final int AUTHORIZATION_STATE = 0; /*** A constant representing the POP3 transaction state. ***/ public static final int TRANSACTION_STATE = 1; /*** A constant representing the POP3 update state. ***/ public static final int UPDATE_STATE = 2; static final String _OK = "+OK"; static final String _ERROR = "-ERR"; // We have to ensure that the protocol communication is in ASCII // but we use ISO-8859-1 just in case 8-bit characters cross // the wire. private static final String __DEFAULT_ENCODING = "ISO-8859-1"; private int __popState; private BufferedWriter __writer; private StringBuffer __commandBuffer; BufferedReader _reader; int _replyCode; String _lastReplyLine; Vector _replyLines; /*** * A ProtocolCommandSupport object used to manage the registering of * ProtocolCommandListeners and te firing of ProtocolCommandEvents. ***/ protected ProtocolCommandSupport _commandSupport_; /*** * The default POP3Client constructor. Initializes the state * to DISCONNECTED_STATE. ***/ public POP3() { setDefaultPort(DEFAULT_PORT); __commandBuffer = new StringBuffer(); __popState = DISCONNECTED_STATE; _reader = null; __writer = null; _replyLines = new Vector(); _commandSupport_ = new ProtocolCommandSupport(this); } private void __getReply() throws IOException { String line; _replyLines.setSize(0); line = _reader.readLine(); if (line == null) throw new EOFException("Connection closed without indication."); if (line.startsWith(_OK)) _replyCode = POP3Reply.OK; else if (line.startsWith(_ERROR)) _replyCode = POP3Reply.ERROR; else throw new MalformedServerReplyException( "Received invalid POP3 protocol response from server."); if (_commandSupport_.getListenerCount() > 0) _commandSupport_.fireReplyReceived(_replyCode, getReplyString()); _replyLines.addElement(line); _lastReplyLine = line; } /*** * Performs connection initialization and sets state to * AUTHORIZATION_STATE . ***/ protected void _connectAction_() throws IOException { super._connectAction_(); _reader = new BufferedReader(new InputStreamReader(_input_, __DEFAULT_ENCODING)); __writer = new BufferedWriter(new OutputStreamWriter(_output_, __DEFAULT_ENCODING)); __getReply(); setState(AUTHORIZATION_STATE); } /*** * Adds a ProtocolCommandListener. Delegates this task to * _commandSupport_ . *

* @param listener The ProtocolCommandListener to add. ***/ public void addProtocolCommandListener(ProtocolCommandListener listener) { _commandSupport_.addProtocolCommandListener(listener); } /*** * Removes a ProtocolCommandListener. Delegates this task to * _commandSupport_ . *

* @param listener The ProtocolCommandListener to remove. ***/ public void removeProtocolCommandistener(ProtocolCommandListener listener) { _commandSupport_.removeProtocolCommandListener(listener); } /*** * Sets POP3 client state. This must be one of the * _STATE constants. *

* @param state The new state. ***/ public void setState(int state) { __popState = state; } /*** * Returns the current POP3 client state. *

* @return The current POP3 client state. ***/ public int getState() { return __popState; } /*** * Retrieves the additional lines of a multi-line server reply. ***/ public void getAdditionalReply() throws IOException { String line; line = _reader.readLine(); while (line != null) { _replyLines.addElement(line); if (line.equals(".")) break; line = _reader.readLine(); } } /*** * 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. *

* @exception IOException If there is an error in disconnecting. ***/ public void disconnect() throws IOException { super.disconnect(); _reader = null; __writer = null; _lastReplyLine = null; _replyLines.setSize(0); setState(DISCONNECTED_STATE); } /*** * Sends a command an arguments to the server and returns the reply code. *

* @param command The POP3 command to send. * @param args The command arguments. * @return The server reply code (either POP3Reply.OK or POP3Reply.ERROR). ***/ public int sendCommand(String command, String args) throws IOException { String message; __commandBuffer.setLength(0); __commandBuffer.append(command); if (args != null) { __commandBuffer.append(' '); __commandBuffer.append(args); } __commandBuffer.append(SocketClient.NETASCII_EOL); __writer.write(message = __commandBuffer.toString()); __writer.flush(); if (_commandSupport_.getListenerCount() > 0) _commandSupport_.fireCommandSent(command, message); __getReply(); return _replyCode; } /*** * Sends a command with no arguments to the server and returns the * reply code. *

* @param command The POP3 command to send. * @return The server reply code (either POP3Reply.OK or POP3Reply.ERROR). ***/ public int sendCommand(String command) throws IOException { return sendCommand(command, null); } /*** * Sends a command an arguments to the server and returns the reply code. *

* @param command The POP3 command to send * (one of the POP3Command constants). * @param args The command arguments. * @return The server reply code (either POP3Reply.OK or POP3Reply.ERROR). ***/ public int sendCommand(int command, String args) throws IOException { return sendCommand(POP3Command._commands[command], args); } /*** * Sends a command with no arguments to the server and returns the * reply code. *

* @param command The POP3 command to send * (one of the POP3Command constants). * @return The server reply code (either POP3Reply.OK or POP3Reply.ERROR). ***/ public int sendCommand(int command) throws IOException { return sendCommand(POP3Command._commands[command], null); } /*** * Returns 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. *

* @return The last server response. ***/ public String[] getReplyStrings() { String[] lines; lines = new String[_replyLines.size()]; _replyLines.copyInto(lines); return lines; } /*** * Returns 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. *

* @return The last server response. ***/ public String getReplyString() { Enumeration enum; StringBuffer buffer = new StringBuffer(256); enum = _replyLines.elements(); while (enum.hasMoreElements()) { buffer.append((String)enum.nextElement()); buffer.append(SocketClient.NETASCII_EOL); } return buffer.toString(); } }

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