pop3.java

java编写的pop3协议（网络公开代码）

package com.jthomas.pop;

/*
 * pop3.java
 * Copyright (c) 1996 John Thomas  [e-mail]
 *      All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for commercial or non-commercial purposes
 * is hereby granted provided that this copyright notice
 * appears in all copies.
 *
 * LIMITATION OF LIABILITY.  UNDER NO CIRCUMSTANCES AND UNDER NO
 * LEGAL THEORY, SHALL THE AUTHOR OF THIS CLASS BE LIABLE TO YOU
 * OR ANY OTHER PERSON FOR ANY INDIRECT, SPECIAL, INCIDENTAL OR
 * CONSEQUENTIAL DAMAGES OF ANY KIND. 
 *
 */

import java.io.*;
import java.util.*;
import java.net.*;

/**
 *
 * <p>Get the latest version of this and other classes in
 * <a href="http://www.geocities.com/SunsetStrip/Studio/4994/java.html">
 * Stefano Locati's Java page.</a>
 *
 * <p>Interface to a POP3 mail server. Can be used to check, fetch 
 * and delete mail messages.
 * Based on the 
 * <a href="http://ds.internic.net/rfc/rfc1939.txt">rfc1939.txt</a>
 * definition for the Post Office Protocol - Version 3 (obsoletes 
 * RFC 1725).
 * <b>If mailhost, user, password are not supplied to the 
 * constructor, then they must be specified on the connect and
 * login calls.</b>
 *
 * <p>The <code>APOP</code> command is not supported by the 
 * <code>pop3</code> class. But there is an <code>apop</code> class
 * that extends <code>pop3</code> to add <code>APOP</code> support.
 * It can be used just like the pop class, just create an apop object
 * instead a pop object. The apop class still works even if the 
 * <code>POP3</code> server doesn't support <code>APOP</code> login.
 *
 * <p>Simple Usage Example to display the size of each message.
 * <pre>
 *   pop3 pop = new pop3(host, user, password);
 *   popStatus status = pop.connect();
 *   if ( status.OK() )
 *    	status = pop.login();
 *   if ( status.OK() ) {
 *       status = pop.list();
 *       String[] responses = status.Responses();
 *       for(int i=0; i< responses.length; i++) {
 *         System.out.println("Message[" + i + "]='" + responses[i] + "'");
 *       }
 *       status = pop.quit();
 *   } 
 * </pre>
 *
 * <p>The following methods try to closely implement the corresponding
 *    POP3 server commands.  See RFC1939.
 *
 * <pre>
 *   popStatus     stat()
 *   popStatus     list()
 *   popStatus     list(msgnum)
 *   popStatus     retr(msgnum)
 *   popStatus     dele(msgnum)
 *   popStatus     noop()
 *   popStatus     quit()
 *   popStatus     top(msgnum,numlines)
 *   popStatus     uidl(msgnum)
 * </pre>
 *
 *  <ul><li>The indicated methods have additional multiline output
 *    that can be retrieved with the get_Responses method for
 *    the popStatus object.  i.e.
 *  <pre>
 *       popStatus status = mypopserver.list()
 *       String[] list = status.get_Responses()
 *  </pre>
 *
 *  <li>The following methods are convenience functions for the client
 *  <pre>
 *       popStatus  appendFile(filename,msgnum)
 *
 *       int get_TotalMsgs() Number of mail messages on server
 *       int get_TotalSize() Total size of all mail messages
 *                           _TotalSize and _TotalMsgs are set during
 *                           login() by an internal stat() command
 *  </pre>
 * 
 *  <li>The status of a POP request is returned in an instance of
 *    the popStatus class.
 *    popStatus has the following methods to extract the returned info.
 *  <pre>
 *       boolean    OK()        True if request had no errors
 *       String     Response()  The initial line returned by POP server
 *                              that starts with either +OK or -ERR
 *       String[]   Responses() If command returns multiple lines of
 *                              data (RETR, TOP, LIST) then this method
 *                              will return the lines in an array.
 *  </pre>
 * 
 *  <li>Public debugging Methods.
 *  <pre>
 *       void     setDebugOn(boolean)      turn on debug output
 *       void     set_DebugFile(filename)  Set filename for debug output
 *       void     debug(String DebugInfo)  Display string on stdout
 *  </pre>
 *  </ul>
 *
 * @author <b>Original author:</b> John Thomas
 *     <a href="mailto:[e-mail]">[e-mail]</a>
 * @author <b>Current maintainer:</b> Stefano Locati 
 *  <a href="mailto:[e-mail]">[e-mail]</a> or
 *  <a href="mailto:[e-mail]">[e-mail]</a>
 * @version $Revision: 1.13 $ $Date: 1998/09/02 08:05:29 $
 * @see apop
 */

public
class pop3   {

    /** Authorization State */
    protected final int AUTHORIZATION = 1;

    /** Transaction State */
    protected final int TRANSACTION = 2;

    /** Update State */
    protected final int UPDATE = 3;


    /** Number of mail messages on server */
    protected int _TotalMsgs = 0;
    
    /** Total size of all messages on server */
    protected int _TotalSize = 0;

    /** status used by Send/Recv */
    protected boolean _StatusOK = false;

    /** Session State */
    protected int State = 0;

    /** The last POP3 command sent to the server */
    protected String LastCmd;

    /** POP3 server host name */
    protected String Host = null;

    /** Port on which the POP3 server listens to */
    protected int Port = 110;

    /** Mailbox user name */
    protected String User = null;

    /** Mailbox password */
    protected String Password = null;

    /** Socket connected to the server  */
    protected Socket server;

    /** Input stream connected to the server socket */
    protected BufferedReader serverInputStream;

    /** Output stream connected to the server socket */
    protected DataOutputStream serverOutputStream;

    /** debug On switch */
    private boolean debugOn=false;


    /** 
     *  Creates the object. No work is done.
     *  @param host      a pop3 server host name 
     *  @param user      a mailbox user name
     *  @param password  a mailbox password 
     */
    public pop3(String host, String user, String password) {
	Host = host;
	User = user;
	Password = password;
    }


    /** 
     *  Creates the object. No work is done
     *  You will have to supply host, user and password through
     *  connect() and login() methods.
     *  @see #connect(java.lang.String)
     *  @see #login(java.lang.String, java.lang.String)
     */
    public pop3() {
    }


    /**
     *  Makes a socket connection to the specified
     *  host (port 110).
     *  @param host        a pop3 server host name
     *  @return popStatus:  result of this operation
     */
    public popStatus connect(String host) {
	// If method specifies the host name then save it and
	// call the default connect method
	Host = host;
	return this.connect();
    }

    /**
     *  Makes a socket connection to the specified
     *  host and port.
     *  @param host        pop3 server host name
     *  @param port        TCP port to connect to
     *  @return popStatus:  result of this operation
     */
    public popStatus connect(String host, int port) {
	// If both host and port are specified then save them
	// and then call the default connect method
	Host = host;
	Port = port;     // Normally this would be 110 (RFC 1725)
	return this.connect();
    }

    /** 
     *  Makes a socket connection to the host specified
     *  in the constructor (port 110).
     *  @return popStatus:  result of this operation
     */
    public synchronized popStatus connect() {
	popStatus status = new popStatus();
	debug("Connecting to " + Host + " at port " + Port);
	if (Host == null) {
	    status._Response = "-ERR Host not specified";
	    status._OK = false;
	    return status;
	}

	try {
	    server = new Socket(Host,Port);
	    if (server == null) {  // a failure with no exception????
		debug("-ERR Error while connecting to POP3 server");
		status._OK = false;
		status._Response = "-ERR Error while connecting to POP3 server";
	    } else {
		debug("Connected");
		// get the input stream that we will use to read from the server
		serverInputStream = new BufferedReader(
		    new InputStreamReader(server.getInputStream()));
		if (serverInputStream == null) {
		    debug("Failed to setup an input stream.");
		    status._OK = false;
		    status._Response = "-ERR Error setting up input stream";
		    server = null;
		}
		serverOutputStream = new DataOutputStream(
                    server.getOutputStream() );
		if (serverOutputStream == null) {
		    debug("Failed to setup an output stream.");
		    status._OK = false;
		    status._Response = "-ERR Error setting up output stream";
		    server = null;
		}
	    }
	}
	catch (Exception e) {
	    String msg = "Exception! " + e.toString();
	    debug(msg);
	    status._OK = false;
	    status._Response = msg;
	    server = null;
	}
	
	if (server != null) {
	    status._OK = true;
	    // POP protocol requires server to send a response on the
	    // connect.  We will now get that response and parse it
	    _StatusOK = true;    // Fake doing send() before recv()   
	    status._Response = recv();
	    Parse(status,2);
	    debug("Response=" + status._Response);
	}

	if (status._OK)
	  State = AUTHORIZATION;
	
	return status;
    }

    //----------------------------------------------------------

    /**
     *  Login the specified user with the specified password.<br>
     *  If the login is successful, a "STAT" command is issued
     *  to get the current number of messages.
     *  @param user        a mailbox user name
     *  @param password    a mailbox password
     *  @return popStatus: result of this operation
     */    
    public popStatus
    login(String user, String password) {
	User = user;
	Password = password;
	return login();
    }

   /**
     *  Login with the user and password specified in the 
     *  constructor.<br>
     *  If the login is successful, a <code>STAT</code> 
     *  command is issued to get the current number of 
     *  messages.
     *  @return popStatus: result of this operation
     */    
    public synchronized popStatus login() {
	popStatus status = new popStatus();
	
	if (User == null || Password == null) {
	    status._Response = "-ERR Userid or Password not specified";
	    return status;
	}
	if ( server != null )  {
	    send("USER " + User);
	    status._Response = recv();
	    Parse(status,1);
	    if (status._OK) {
		send("PASS " + Password);
		status._Response = recv();
		Parse(status,1);
		if (status._OK) {
		    State = TRANSACTION;
		    // Now we will do an internal STAT function
		    popStatus statStatus = stat();
		}   
	    }
	}
	return status;
    }


     //----------------------------------------------------------

    /**
     *  Closes the socket connection.
     *  Use <code>quit</code> for a normal termination.
     *  @see #quit()
     */
    public synchronized void close() {
	debug("Closing socket");
	try {
	    server.close();
	    State = 0;
	} catch (IOException e) {
	    debug("Failure in server.close()");
	}
    }
    
    //----------------------------------------------------------

    /**
     *  Gets the number of messages and their total size from
     *  the server.
     *  @return popStatus: result of this operation
     */
    public synchronized popStatus stat() {
	popStatus status = new popStatus();
	if (State != TRANSACTION) {
	    status._Response = "-ERR Server not in transaction mode";
	    return status;
	}
	send("STAT");        // Issue the STAT command
	status._Response = recv();     // read the response
	String[] tokens = Parse(status, 4);
     
	if (status._OK) {
	    _TotalMsgs = Convert.toInt(tokens[1]);
	    _TotalSize = Convert.toInt(tokens[2]);
	}
	
	return status;
    }

    //----------------------------------------------------------

    /**
     *  Quits the session with the POP3 server.
     *  After receiving a goodbye message from the server, 
     *  the socket is closed.
     *  @return popStatus
     */
    public synchronized popStatus quit() {
	popStatus status = new popStatus();
	send("QUIT");        // Issue the STAT command
	State = UPDATE;
	status._Response = recv();     // read the response
	String[] tokens = Parse(status,2);
	close();
	
	return status;
    }
    
    
    //----------------------------------------------------------

    /**
     *  Gets the size of the specified mail message.
     *  @param msgnum      message number
     *  @return popStatus: result of this operation
     */
    public synchronized popStatus list(int msgnum) {
	popStatus status = new popStatus();
	int i=0;
	
	send("LIST " + msgnum);        // Issue the LIST n command
	status._Response = recv();     // read the response
	String[] tokens = Parse(status,2);
	return status;
    }
    
    /**
     *  Gets a list of messages and the size of each one.
     *  @return popStatus: result of this operation
     */
    public synchronized popStatus list() {
	
	popStatus status = new popStatus();
	send("LIST");        // Issue the LIST command
	
	recvN(status);     // read the response
	String[] tokens = Parse(status,2);
	
	return status;
    }
    
    //----------------------------------------------------------